Sanity check, please...

[Rich Z]

Well, I've been plugging away at this tune for what seems like forever and I think I'm about ready to wrap it up.

Did the VE calibration and most recently doing the MAF calibration. Car runs really well, and the logs (to my untrained eye) don't show anything devastating going on.

But I am new at this and figure I should have some trained eyes look over the tune to see if I am just missing something that is glaringly obvious to you.

Anyway, here's the specs of what is under the hood.

2002 Corvette Z06
custom 427 built by LME (9.8:1 CR)
STS rear mounted twin turbos
90mm LS9 throttle body
FAST 102mm intake
LGM long tube headers
Mild turbo cam (232 228/116/.630 .630/109.25)
MAP referenced fuel pressure regulator
Reworked fuel system with dual intank fuel pumps
Fuel injectors from FIC (72 lb/hr)
2 bar MAP sensor


I think that's everything pertinent.

The attached tune is as it sits right now while I've been calibrating the MAF. At least that's what I THINK I've been doing. :) So all fuel trims and adders are disabled (as best I can tell).

Yeah, I know this was supposed to be a speed density tune, but I'm not really sold on going that route. When I re-enabled the MAF, the car just seemed to run a lot smoother at normal driving speeds. So my intent (if this is possible to do) is to run off of the MAF till it tops out at 12000hz and then run from the VE table from there. I also intend to re-enable the STFTs and LTFTs as well. Is this is inadvisable, then heck, I'm all ears....

Issues that still remain that I am aware of is that the cold start idle is a bit unstable when I kick the gas pedal and the rpms drop down. It has trouble stabilizing itself afterwards. And there is still a slight bit of bucking and when I take my foot off of the gas pedal at low speeds/low rpms.

Anyway, I would appreciate anyone taking a look at this to see if I am completely out of the ball park on what I've been doing. This has been a learn as I go project with my having to look at just about every table in EFILive to try to figure out what they are doing, and whether they are applicable in what I WANT to do with the tune. So any mistakes in the tune are my own, as although I did have a tuner help me get started initially, I've pretty much taken the ball and run with it on my own for a while now.

Thanks in advance for any advice.....

[BLK02WS6]

I would rethink the MAF idea - I would not do it that way - If you work on the SD tune, you can get it to be just as responsive as a MAF tune.
Other than that:
-You have several lean spots in the VE - most noteably in the 4000-5200 RPM range - need to richen all of those up using the BEN factor. You are also going very lean under boost.
-You are commanding way too rich too soon - using the commanded fuel vs RPM table (B3647) to command boost fueling is not the way to go - that will cause the car to be too rich when rolling into the throttle, and it will bog. May not see it going straight to the mat, but rolling in you will. The way I do it is to command naturally aspirated fueling in the 100 kpa column of B3647 - then, use the PE based on RPM table (B3618) to command boost fueling - do this by setting B3613 to around 110 kpa (may need to vary this a little to get the right transition). Make sense?
-Why not use the boost timing table? I set the HO table to naturally aspirated numbers, and then use the boost timing table to pull based on boost - this is much more accurate than trying to do it in the HO table alone...

[Rich Z]

I would rethink the MAF idea - I would not do it that way - If you work on the SD tune, you can get it to be just as responsive as a MAF tune.

Can you tell me WHY you suggest that?


Other than that:
-You have several lean spots in the VE - most noteably in the 4000-5200 RPM range - need to richen all of those up using the BEN factor. You are also going very lean under boost.

Can I ask how are you determining that? When I did the VE calibration using BEN, here's one of the MAPs I used to then modify the VE table:

http://www.corvetteflorida.com/pics/ben1_28_008.jpg


-You are commanding way too rich too soon - using the commanded fuel vs RPM table (B3647) to command boost fueling is not the way to go - that will cause the car to be too rich when rolling into the throttle, and it will bog. May not see it going straight to the mat, but rolling in you will. The way I do it is to command naturally aspirated fueling in the 100 kpa column of B3647 - then, use the PE based on RPM table (B3618) to command boost fueling - do this by setting B3613 to around 110 kpa (may need to vary this a little to get the right transition). Make sense?

Well, actually ALL of the throttle I have been using have been rolling into it. And I have not experienced any bogging at all, at any rpm. Well, except maybe at very low rpms in sixth gear just to see how the engine responds. In the tune and log I provided I do not have PE enabled at all. I thought to calibrate the MAF, I should have PE completely out of the equation. And I am presuming that I'm not using the VE table neither as I thought I am running off of the MAF and not the VE table at all. But I won't be shocked at all to learn I'm doing that wrong and all is not as it seems to me. :)

Truth be known, when I looked at my logs early on, it appeared to me that I was seeing a big gulp of air giving me a LEAN condition at throttle engagement. I may have been trying to address that a while back or else my trying to correct another problem affected that particular part of the tune. Some of these tables are like pulling a loose thread on a garment and then seeing where the pull shows up from that thread.


-Why not use the boost timing table? I set the HO table to naturally aspirated numbers, and then use the boost timing table to pull based on boost - this is much more accurate than trying to do it in the HO table alone...

Well, I don't know. I thought I WAS using it. Did I miss something that should enable it? Honestly their are a lot of tables and enablers for timing, so I'd be lying if I said I have a good handle on all the options. :( So what am I missing with doing it the way you are suggesting?

Thanks for your help!

In case it's not understood, I AM a newbie at this and struggling through trying to learn this stuff. So I am not going to be embarrassed or get defensive if someone tells me I'm doing this completely wrong. The tutorials here are NOT designed for newbies at all. And yeah, the information is on this site, SOMEWHERE, and in bits and pieces. But from what I can see about the longevity of new people coming here, NO ONE has the patience to read through each and every post on this forum in order to put all the pieces together into a coherent picture. So I've been spending most of my time LOOKING at the tables and descriptions, then looking for the answers to specific questions when I hit that wall. So yeah, there are going to be gaps in my knowledge "base". Just wanted to clarify the level I am working from....:confused:

[BLK02WS6]

Sorry - I mis-read it. I thought you were getting ready to do the MAF table. Either way, it is lean in several places. I'll try to go through some explanations and post some screenshots in a bit - during lunch time if I get a break...

[voda1]

Get car on a dyno and work out the timing and fuel settings.

Or now that you have better understanding of tune and scanner tools you could do what many experienced turners
have recommended and start over from scratch with a stock tune.

[BLK02WS6]

The reason to go SD is because you are getting close to the 512 grams/sec limit of the PCM. You could scale everthing to get away from it, but that is quite a process that I don't think you want to undertake... There is no reason not to go SD with a COS. It can be tuned to run the same as a MAF tune - weather and altitude changes are not an issue as some believe...

Here is where I was saying you are lean under boost:
http://i190.photobucket.com/albums/z135/blk02ws6/screen1.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen1.jpg.html)

And, here is one of many places it is lean rolling into the throttle:
http://i190.photobucket.com/albums/z135/blk02ws6/screen2.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen2.jpg.html)

The reason you aren't seeing the problem I was talking about with too much fuel is because your actual isn't at commanded yet - once you correct it, it would be happening. And, like you said above, it will bog when you load the motor into boost in 5th or 6th gear and any time you go up a small hill or grade in the road. If you set the commanded fueling using the method I discuss, you can keep the cruise/lugging commanded fueling where it should be. You follow me?

[BLK02WS6]

Here you can see that you don't have any timing pulled until 185 kpa using the boost timing table:

http://i190.photobucket.com/albums/z135/blk02ws6/screen3.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen3.jpg.html)

It is using only the high octane table. You can do it that way, but it is better - in my opinion - to pull based on boost. That way, if boost drops off, timing picks back up. It would be possible to map the high octane table like that, but it would be difficult at best. Much easier to use naturally aspirated timing in the high octane table and pull based on boost.

[Rich Z]

OK, yes, I see what you mean. So should I roll back and work with strictly the VE table again? Failing the MAF?

What do I need to do in order to make certain that the boost timing table is the one in charge when under boost? I'm still struggling with trying to figure out how to determine which of the many timing tables are being used at any given moment.

Oh and as for an earlier comment about using a dyno, that just is not an option. There is no one around this area that has a dyno that I know of that I would trust putting my car in their shop. There is a lot of unpleasant nightmare-level history involving getting my car from the point where I decided on the extensive hardware mods and where I am today with it. Let's just say that their claims weren't proven by facts.

And I certainly do not want to start over from scratch with a stock tune. My car went into the first shop to do the engine replacement on 10-27-2009 and my car has been pretty much laid up ever since then. Heck, the car was back home in my garage on my lift for over a year as I learned what I needed to do to fix the crap that two shops bungled on the build. You would not have believed the fuel system the first shop put in there. I had to learn as I go every step of the way there too. I'm ready to get this OVER with ASAP so I can just drive it and enjoy being behind the wheel again without being all wired up for data logging.

I haven't minded the time trying to learn this tuning stuff, but I don't want to spend all eternity doing it. The reason I posted here was to make sure that I'm not doing something stupid that will hurt my engine. A lot of this is pure Greek to me. There might be better and more eloquent ways to do something but I pretty much want to be able to run with mostly what I have here now and get this behind me. Maybe later on I will think about doing it all completely over when I learn more about tuning, but just not right now. I can live with "good enough" for a spell now.

Thanks for your help with this. And I hope I won't be bugging you too much by wanting to know the WHY of some things.

[BLK02WS6]

The first thing I would do is get the fueling straightened out - worry about the timing after that because it is not bad for now. Yes, go back to speed density and work on the VE. Do you want to set up the fuel tables like I had said earlier?

[Rich Z]

Is this what you are referring to?

The way I do it is to command naturally aspirated fueling in the 100 kpa column of B3647 - then, use the PE based on RPM table (B3618) to command boost fueling - do this by setting B3613 to around 110 kpa (may need to vary this a little to get the right transition). Make sense?

Honestly I'm a bit hazy on how B3613 works in relation to B3647 and B3618. I've been using B3647 as the switch to turn STFT on and off as I calibrate the VE and MAF. As for B3618, I haven't really done more than some rudimentary "what if" stuff with PE as I was leaving that for when I got the VE and MAF stuff pretty much squared away.

So as far as making sense, well the pieces do, but not the stew produced when they are mixed together. But as long as I don't have to take too many steps backwards, I'm willing to give it a shot if you will give me some clues on how to proceed without making things worse for myself.

Thanks.

[Rich Z]

Oh yeah, forgot to mention that we are having rain storms passing through here so I don't take the car out on wet roads. I just barely got the last logging done before another storm front passed through. :)

[Rich Z]

BTW, how exactly should I set up the MAP for calibrating the VE properly? Especially since some of the values will be ABOVE what B0101 shows? I've taken a look at all of the tutorials, and it seems that for one reason on another, they don't exactly apply to what I need. So to make sure I am doing this correctly, IS there a tutorial that steps through calibrating the VE table (or boost equivalent) on a boosted engine? If I'm going to be "measuring" the values of my VE table then I guess I need to make sure I am using the correct measuring tool(s).

Honestly, I've got several MAPs set up showing boosted cells, but I'm not at all sure they are correct.

Thanks.

ps I was going to post the last log I did while working on the VE table, but I didn't drive the engine over 3600 rpm, so I'm guessing it's not going to tell you anything. If I remember correctly, there were a LOT of cops out on the road that day.... :(

[Rich Z]

Been reading this over again and it dawned on me that I forgot a detail. I wondered why the log was showing lean in spots when I realized that the log was for the tune attached in that post. The MAF has been further tweaked using that log and is tune #0019, which has NOT been logged yet. And it was specifically in the higher rpm range that I did the tweaking of the MAF table.

So let me back up a bit and ask something specific.

Does the timing look safe based on what is seen in the log? 40+* just seems to be a lot to me....

[joecar]

There are big advantages for abandoning the MAF...

like BLK02WS6/Bret said, the PCM has an upper limit of 512 g/s on the MAF, and scaling any table that references airmass or airflow is very tedious;e

it is one less part that can fail (especially when running boost, if MAF fails you could be in big trouble).

When IFR and VE are correct, fueling will be immune to changes in weather... the VE table units are g*K/kPa, i.e. VE table is cylinder airmass normalized for temperature and pressure (or if you like, it is normalized for density).

[joecar]

Bret's suggestion of using B3647 to set NA fueling and using B3618 to set boost fueling is an excellent idea...

B3613 sets the MAP kPa threshold for enabling PE...

so, PE enables when all the PE enablers are satisfied: B3613, B3616, and the others.

then, commanded fueling is determined like this:
- if PE has not enabled, then B3647 is used for fueling (i.e. B3647 is the only active fueling table);
- if PE has enabled, then fueling is from the richest of B3618 and B3647 (i.e. these are the currently active fueling tables);

notes:
- if MAP is beyond the last column of B3647, the last column is extrapolated, so B3647 fueling is this last column (now re-read the previous paragraph with this in mind);
- if any protection modes enable, then there will be extra active fueling tables, commanded fueling is the richest of all the active tables (e.g. COTP, EPM, PPM);


COTP = catalytic over temp protection
EPM = engine protection mode
PPM = piston protection mode

[joecar]

Make a single map that covers both VE tables...

then simply copy 0-105kPa columns to Main VE B0101 and 105-285kPa columns to Boost VE A0009.

[Rich Z]

There are big advantages for abandoning the MAF...

This obviously begs the question of WHY did GM put in a MAF then? Surely they are always looking to cut costs by eliminating unnecessary hardware and circuitry. I'm sure those engineers know all about speed density tuning. So why use a MAF and bear that additional manufacturing expense if there wasn't a real good reason for it?


like BLK02WS6/Bret said, the PCM has an upper limit of 512 g/s on the MAF, and scaling any table that references airmass or airflow is very tedious;e

What happens when that upper limit is reached? What does the PCM DO? If you purposely fail the MAF at 12000 via C2901, does the VE table then take over?


it is one less part that can fail (especially when running boost, if MAF fails you could be in big trouble).

Reading between the lines, my impression is that the VE table is a backup for the MAF. So if the MAF fails, then the VE table is used. Isn't the output of the MAF compared with another table somewhere indicating what acceptable variances are acceptable compared with the VE table?


When IFR and VE are correct, fueling will be immune to changes in weather... the VE table units are g*K/kPa, i.e. VE table is cylinder airmass normalized for temperature and pressure (or if you like, it is normalized for density).

[Rich Z]

Bret's suggestion of using B3647 to set NA fueling and using B3618 to set boost fueling is an excellent idea...

B3613 sets the MAP kPa threshold for enabling PE...

so, PE enables when all the PE enablers are satisfied: B3613, B3616, and the others.

then, commanded fueling is determined like this:
- if PE has not enabled, then B3647 is used for fueling (i.e. B3647 is the only active fueling table);
- if PE has enabled, then fueling is from the richest of B3618 and B3647 (i.e. these are the currently active fueling tables);

notes:
- if MAP is beyond the last column of B3647, the last column is extrapolated, so B3647 fueling is this last column (now re-read the previous paragraph with this in mind);
- if any protection modes enable, then there will be extra active fueling tables, commanded fueling is the richest of all the active tables (e.g. COTP, EPM, PPM);


COTP = catalytic over temp protection
EPM = engine protection mode
PPM = piston protection mode

I think perhaps I have just been looking at Power Enrichment as something different that is not correct. I've been looking it as being the programmable equivalent of the accelerator pump on a carburetor. Back in those days, the manual accelerator pump would give an extra squirt of fuel directly into the carburetor upon spirited gas pedal pressure. I presumed that this function must be incorporated somewhere into the PCM tuning software, and PE just sounded like the logical equivalent.

Have I been barking up the wrong tree?

I believe I had PE disabled when I was doing what I thought was calibrating the MAF. Of course, I just now stumbled on that B0120 setting that I somehow overlooked, so I'm not even sure WHAT I was really doing....

[Rich Z]

Make a single map that covers both VE tables...

then simply copy 0-105kPa columns to Main VE B0101 and 105-285kPa columns to Boost VE A0009.

Somewhere along the line I must have done that because I do have a MAP that shows kPa columns from 15 to 285. When I look at the log file included in this thread, I have to make the map display all cells with at least one hit to see much above 100kPa. Apparently even rolling into those high revs still doesn't give a lot of sampling for each cell. But from what I can see, the highest value there is only 1.09. I was thinking that that isn't TOO bad, now is it?

[joecar]

This obviously begs the question of WHY did GM put in a MAF then? Surely they are always looking to cut costs by eliminating unnecessary hardware and circuitry. I'm sure those engineers know all about speed density tuning. So why use a MAF and bear that additional manufacturing expense if there wasn't a real good reason for it?GM has produced many EFI vehicles without MAF's.


What happens when that upper limit is reached? What does the PCM DO? If you purposely fail the MAF at 12000 via C2901, does the VE table then take over?
When upper limit is reached, the MAF is pegged at 512 g/s.

You have an interesting point about failing the MAF at 12000 Hz... it will fail immediately (DTC triggers, and now VE table is the sole source of cylinder airmass)... but it won't re-enable when the frequency falls below 12000 Hz... for the MAF to re-enable, the MAF DTC must be cleared by the PCM, this involves some amount of drive-cycle (it doesn't just clear instantly).


Reading between the lines, my impression is that the VE table is a backup for the MAF. So if the MAF fails, then the VE table is used. Isn't the output of the MAF compared with another table somewhere indicating what acceptable variances are acceptable compared with the VE table?You are correct, the VE table is the failover when the MAF fails...

but also note that at lower airflow the MAF does not deal very well with flow transition, so the PCM temporarily does use VE during airflow transients.

[joecar]

I think perhaps I have just been looking at Power Enrichment as something different that is not correct. I've been looking it as being the programmable equivalent of the accelerator pump on a carburetor. Back in those days, the manual accelerator pump would give an extra squirt of fuel directly into the carburetor upon spirited gas pedal pressure. I presumed that this function must be incorporated somewhere into the PCM tuning software, and PE just sounded like the logical equivalent.

Have I been barking up the wrong tree?

I believe I had PE disabled when I was doing what I thought was calibrating the MAF. Of course, I just now stumbled on that B0120 setting that I somehow overlooked, so I'm not even sure WHAT I was really doing....Carburetor accelerator pump provided momentary extra shot of fuel to avoid transient lean when throttle butterfly was rapidly opened...

PE is different than this as you can see by its enabler tables.

Never disable PE during tuning, it provides enrichment when you're engine is at load... of course you mesh this together with B3647 as said above.

[joecar]

Somewhere along the line I must have done that because I do have a MAP that shows kPa columns from 15 to 285. When I look at the log file included in this thread, I have to make the map display all cells with at least one hit to see much above 100kPa. Apparently even rolling into those high revs still doesn't give a lot of sampling for each cell. But from what I can see, the highest value there is only 1.09. I was thinking that that isn't TOO bad, now is it?You mean the average BEN in the map was 1.09 in one of the high load VE cells, and the surrounding cells were closer to 1.00... that's not too bad...

have a closer look at what surrounds the 1.09 cell and judge whether it is correct (remember, VE phyiscally does not have sudden jumps)...

[ do the surrounding cells need to come up a little, or should the 1.09 cell be pushed down a little...? ]

[Rich Z]

You have an interesting point about failing the MAF at 12000 Hz... it will fail immediately (DTC triggers, and now VE table is the sole source of cylinder airmass)... but it won't re-enable when the frequency falls below 12000 Hz... for the MAF to re-enable, the MAF DTC must be cleared by the PCM, this involves some amount of drive-cycle (it doesn't just clear instantly).


Ah, so, that one statement makes using the MAF a completely moot point for me. I didn't realize that once it is failed, it STAYS failed. I had hoped it was more dynamic than that and I could possibly run MAF when possible, then VE only when needed. So scrap any more attempted calibration of the MAF. So now I have to look more closely at what Bret has suggested I do.

Darn, just spent a lot of unnecessary time on playing with that MAF. I would be miles ahead if I just knew what questions I need to ask when they needed asking. But learned a couple of new things along the way, so I guess it wasn't a complete waste.

BTW, B0120 was set to 7000 in my tune, so what exactly does that mean in this MAF/VE scheme of things? I'm presuming I just have to fail the MAF and be done with it and stick with the VE tables only.

Oh yeah, got to look at PE a bit differently as well. So there really isn't an accelerator pump equivalent in the PCM programming? I was using it because my logs were showing a brief lean spike at gas pedal application so I was trying to get rid of that using the PE options. Ah well, back to the drawing board. Now to find the last tune I did working solely (I think) with the VE tables

Thanks for your help.

[Rich Z]

You mean the average BEN in the map was 1.09 in one of the high load VE cells, and the surrounding cells were closer to 1.00... that's not too bad...

have a closer look at what surrounds the 1.09 cell and judge whether it is correct (remember, VE phyiscally does not have sudden jumps)...

[ do the surrounding cells need to come up a little, or should the 1.09 cell be pushed down a little...? ]

Moot point now. I had MAF enabled for that log, so that was wasted effort. When I get some logs looking at the VE table calibrations, I'll post them up for review. But maybe Bret can give me some pointers on his suggested method for fueling with SD first. Looks like more rain on the way, so I probably won't be taking the car out the next couple of days anyway. Even with my fumbling tuning efforts, the car is a handful at WOT, so I'm certainly not going to run it on wet roads.

[joecar]

B0120 = Dynamic Air Threshold (in RPM)

When MAF is active (and not failed):
when RPM is below B0120: MAF is used for steady state conditions, VE is used for transient conditions;
when RPM is above B0120: MAF is used exclusively.

[Rich Z]

-You are commanding way too rich too soon - using the commanded fuel vs RPM table (B3647) to command boost fueling is not the way to go - that will cause the car to be too rich when rolling into the throttle, and it will bog. May not see it going straight to the mat, but rolling in you will. The way I do it is to command naturally aspirated fueling in the 100 kpa column of B3647 - then, use the PE based on RPM table (B3618) to command boost fueling - do this by setting B3613 to around 110 kpa (may need to vary this a little to get the right transition). Make sense?

OK, so I'm looking at my B3647 table. I'm not sure I know what you mean. What SHOULD I have that table set to? 1.00 in all cells? 0.99 or 1.01 in all cells? Is this table able to be calibrated using BEN map feedback? What relationship does this have to calibrating the VE table in that same kPa range? Aren't they both basically doing the same thing? Adjusting fuel based on air flow values dictated by that table? So you only adjust one and not the other? VE (B0101) is saying that there SHOULD be this much air volume (based on an efficiency quotient as a percentage of 100 percent) in each cylinder at a given rpm at a given vacuum level. B3647 is saying that it wants the AFR to be what is specified in each cell at a given rpm and a given vacuum level. When you collect feedback via data logging to see how far off you are from the results the wideband is reporting, which table needs to be adjusted?

And I have to confess that I'm confused about your statement about commanding boost fueling in this table. I thought "boost" is defined as positive pressure (above ambient atmospheric pressure) and I thought that this would be ABOVE 100 kPa, which is the upper limit of that table.

Sorry, but I'm obviously missing something basic here. Hell, here I was thinking I was actually getting a handle on this till late last night......

[hog]

GM has produced many EFI vehicles without MAF's
Only performance V8 vehicles that GM used Speed Density for was the 1990-95 LT5 ZR-1 Corvette. 1990-91 L98 350 and 1992-93 LT1 Corvette, 1991-92 TPI 305/350, 1993 LT1 Camaro/Firebird. All the turbo V6's TTA,GN, GNX were all MAF, as were all 1985-1989 TPI 305/350 Camaro/Firebird/Vette and 1994-2002 and 2010+ Camaro, and 1994-2013 Vettes all use MAF's. I'm not counting TBI which is indeed Speed Density, but not a performance system IMO. Why is GM holding fast with the MAF system? Here is a pic of the GEN 5 SBC MAF for the 5.3 L83 and 6.2 L86 MAF. They have eight (8) wires.http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/GEN5truckmaf.jpg (http://s1202.photobucket.com/user/Paul_Schermerhorn/media/GEN5truckmaf.jpg.html) peace Hog

[Rich Z]

I'm sure there have been zillions of discussions about the pros and cons of MAF vs speed density tuning. I've been reading what I can, and each camp appears to be as firmly entrenched in their beliefs as the other.

I guess what it all boils down to is if there is any difference in accuracy of the data the PCM needs to correctly determine how much fuel is needed for optimum combustion for each instantaneous NEED of the engine. Has anyone created a map to log MAF frequency data in a RPM x kPa matrix? I'd be curious to see if every cell has a completely unique value in it. If so, then they both may just be different ways of solving the same problem of how much air is available for combustion when the fuel injector needs to be fired. But then again, perhaps all of the tables are just too granular for any realistic analysis in that manner.

[BLK02WS6]

Sorry, I've been tied up with a truck that is giving me a hard time. I'll try to go back through and clear up as much as I can tonight. I'll also make the changes that I'm talking about to your tune attached earlier - then you can do a compare and see the changes I made...

And as far as why GM uses the MAF - I personally believe it is because they don't want to take the time to map out the VE table the way it would need to be in order to get the same driveability and throttle response. It is much easier to use a blend of MAF and VE like they do. I say use the MAF if you can, but there are many applications where you just can't or it doesn't make sense - and yours is one of them...

[Rich Z]

Sorry, I've been tied up with a truck that is giving me a hard time. I'll try to go back through and clear up as much as I can tonight. I'll also make the changes that I'm talking about to your tune attached earlier - then you can do a compare and see the changes I made...

And as far as why GM uses the MAF - I personally believe it is because they don't want to take the time to map out the VE table the way it would need to be in order to get the same driveability and throttle response. It is much easier to use a blend of MAF and VE like they do. I say use the MAF if you can, but there are many applications where you just can't or it doesn't make sense - and yours is one of them...

Thanks. I do appreciate your guidance with this. I had in mind trying to do something that apparently can't be done with my tune. :unsure:

[joecar]

True (you left out some of the Holden/HSV products)...

but when you also include the "plain" engined vehicles models that GM has made, quite a few of those came without a MAF.

But, as you said, by using a MAF, GM must be seeing advantages.

That's a good pic... that has integrated MAF and IAT and what else...?


Only performance V8 vehicles that GM used Speed Density for was the 1990-95 LT5 ZR-1 Corvette. 1990-91 L98 350 and 1992-93 LT1 Corvette, 1991-92 TPI 305/350, 1993 LT1 Camaro/Firebird. All the turbo V6's TTA,GN, GNX were all MAF, as were all 1985-1989 TPI 305/350 Camaro/Firebird/Vette and 1994-2002 and 2010+ Camaro, and 1994-2013 Vettes all use MAF's. I'm not counting TBI which is indeed Speed Density, but not a performance system IMO. Why is GM holding fast with the MAF system? Here is a pic of the GEN 5 SBC MAF for the 5.3 L83 and 6.2 L86 MAF. They have eight (8) wires.http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/GEN5truckmaf.jpg (http://s1202.photobucket.com/user/Paul_Schermerhorn/media/GEN5truckmaf.jpg.html) peace Hog


Bret has a possible advantage for GM using MAF's, to save time by avoiding fine tuning:

...

And as far as why GM uses the MAF - I personally believe it is because they don't want to take the time to map out the VE table the way it would need to be in order to get the same driveability and throttle response. It is much easier to use a blend of MAF and VE like they do.
...

[joecar]

I'm sure there have been zillions of discussions about the pros and cons of MAF vs speed density tuning. I've been reading what I can, and each camp appears to be as firmly entrenched in their beliefs as the other.

I guess what it all boils down to is if there is any difference in accuracy of the data the PCM needs to correctly determine how much fuel is needed for optimum combustion for each instantaneous NEED of the engine. Has anyone created a map to log MAF frequency data in a RPM x kPa matrix? I'd be curious to see if every cell has a completely unique value in it. If so, then they both may just be different ways of solving the same problem of how much air is available for combustion when the fuel injector needs to be fired. But then again, perhaps all of the tables are just too granular for any realistic analysis in that manner.Hi Rich,

yes, there have been many many debates over MAF-vs-SD.


More correctly, since we're talking MAF andor VE, that is the data the PCM uses to correctly calculate how much air filled the cylinder... and then fueling is determined from that based on the fueling tables (i.e. indirectly);

( I know you already know that :) ... to keep learning about the PCM we have to think/speak strictly in terms of what the PCM does )

airmass is tuned, fueling is stated (i.e. fueling follows airmass)

( of course you have to know what to state, but the tuning of this is different, requiring dyno and dragstrip)


I'll dig up some logs containing MAF and I post some pics of MAF x RPM x MAP (noting that MAF is uniquely determined by MAFFREQ).

[BLK02WS6]

Here is your posted tune with only the commanded fueling changes (B3613, B3618, B3647). When I say commanded fueling - I think of it this way - commanded is the target you are trying to get to... the way you get there is by the VE and, if used, MAF tables. So, you set your targets at some sane reasonable value for your setup. Then, you correct the VE table based on your BEN readings until actual fueling (from your wideband readings) equals commanded readings. Then, after you have actual equal to commanded, you put it on a dyno and tweak commanded fueling (actual will follow at this point because you have corrected it already) to obtain optimum torque and horsepower throughout the RPM range.

With timing, start off conservative and raise it on the dyno to find optimum timing throughout the RPM range based on torque and horsepower readings...

[BLK02WS6]

I think Joe cleared up most of your other questions already (or maybe confused you more :mrgreen:)... Joes speaks PCM better than I do... I try to put things in the simplest terms possible cause that is the way I learned. Whatever you do, don't get discouraged! You probably know more than you think... If you don't get something, just ask - Joe is one of the most patient people on the face of the earth and will continue to try and help you pretty much forever... and I try - between the day job, kids, and trying to tune on the side, I don't have a ton of free time...

[joecar]

lol...

Rich, the method is to adjust the VE table until the wideband shows the same fueling as stated/commanded...

[ this requires all other source of airmass to be disabled (i.e. MAF), and it requires all trimming to be disabled (i.e. CL/LTFT/STFT/SOL) ]

[Rich Z]

Here is your posted tune with only the commanded fueling changes (B3613, B3618, B3647). When I say commanded fueling - I think of it this way - commanded is the target you are trying to get to... the way you get there is by the VE and, if used, MAF tables. So, you set your targets at some sane reasonable value for your setup. Then, you correct the VE table based on your BEN readings until actual fueling (from your wideband readings) equals commanded readings. Then, after you have actual equal to commanded, you put it on a dyno and tweak commanded fueling (actual will follow at this point because you have corrected it already) to obtain optimum torque and horsepower throughout the RPM range.

With timing, start off conservative and raise it on the dyno to find optimum timing throughout the RPM range based on torque and horsepower readings...

OK, thanks for helping me with this. I'll take a look at the tune you gave me and see if the pieces fit together in my head.

As for timing, I don't have a dyno available. So I have to do what I can on the street. Luckily I'm in an area where long stretches of pretty deserted roads are easy to come by. Of course, these kinds of roads also have the hazard of a deer deciding to jump in front of you. So from what you can see, does the timing being logged look OK, regardless of how it got there? :)

Hopefully the rain will take a break so I can get the car out and play with this some more. I did spend some time with the VE table in the lower rev range, so I've got to take a stab at some boost readings to get some data logged there.

[Rich Z]

lol...

Rich, the method is to adjust the VE table until the wideband shows the same fueling as stated/commanded...

[ this requires all other source of airmass to be disabled (i.e. MAF), and it requires all trimming to be disabled (i.e. CL/LTFT/STFT/SOL) ]

OK, I think that makes sense to me. Kind of. The VE table is telling the PCM what the air charge is expected to be. The fuel tables tell the PCM what we want the AFR to be based on that air charge. The differences between the commanded AFR and the actual AFR determined by the wideband sensor are the differences between what the VE table IS and what it SHOULD be. Does that sound right?

So in my case, I actually have TWO VE tables to calibrate. One at naturally aspirated MAP values (B0101), and the other at boosted MAP levels (A0009).

Oh, not to change the subject, as this is jumping ahead a bit, but I'm presuming that I will be enabling the STFTs after the VE tables are kicked into line. But what about LTFTs? I was told that I shouldn't use them because they will interfere with boost fueling. Yes or no?

Thanks for the help.... I'm getting there, I think.

[joecar]

OK, I think that makes sense to me. Kind of. The VE table is telling the PCM what the air charge is expected to be. The fuel tables tell the PCM what we want the AFR to be based on that air charge. The differences between the commanded AFR and the actual AFR determined by the wideband sensor are the differences between what the VE table IS and what it SHOULD be. Does that sound right?Yes, you got it.


So in my case, I actually have TWO VE tables to calibrate. One at naturally aspirated MAP values (B0101), and the other at boosted MAP levels (A0009). You can think of the two VE tables being joined at the 105 kPa column... going above 105 kPa is boost.


Oh, not to change the subject, as this is jumping ahead a bit, but I'm presuming that I will be enabling the STFTs after the VE tables are kicked into line. But what about LTFTs? I was told that I shouldn't use them because they will interfere with boost fueling. Yes or no?STFT/SOL can be enabled... (SOL is simply STFT on any stoich cell in B3647); STFT/SOL are instant (they are applied immediately);

LTFT's can also be enabled if they are going to be zero (if VE is accuratly modelling cylinder airmass, then LTFT will be very close to zero)...

the problem with LTFT's is that positive LTFT's are added to fueling in PE mode...

LTFT behavior in CL mode::
- PE not enabled: CL trimming adds LTFT to fueling;
- PE enabled: the last LTFT is rounded up to zero and then added to fueling (on top of PE fueling), see note in next paragraph;
- LTFT's are remembered (learnt) in a 4x4 + 8 array (there are 4x4 MAPxRPM cells plus 8 additional cells for things like idle and WOT);
- a new LTFT is stored (learnt) in a particular cell when the STFT takes an excursion past some threshold (positive or negative)
(and the STFT is then set back to zero);
- the LTFT from the last operating point in the 4x4 array is stored in the WOT cell and added to fueling;

note:
the second point above is saying this:
negative LTFT is rounded up to zero, positive LTFT is retained, the resulting LTFT is added to fueling;

note also:
in CL mode, going to PE retains CL mode (in a manner) and does not go to OL mode
(i.e. B3647 does not become active; the only active fueling table is B3618).

see post #4 here: Summary-Notes (http://forum.efilive.com/showthread.php?14188-Summary-Notes)

[ ok, so what was GM thinking...? The consensus is that they were thinking of protecting the engine as best they can (implying that they were expecting people to hack into their PCM's) ]



Thanks for the help.... I'm getting there, I think.No worries... I hope I haven't confused everything with the description of LTFT's.

[joecar]

Actually, the LTFT array is 4x4 (MAPxRPM) and there are an additional 8 cells (i.e. for WOT, for idle with/without AC, ...).

[Rich Z]

No worries... I hope I haven't confused everything with the description of LTFT's.

Well, honestly a lot of that didn't sink right in. But I think the gist of it is, I think, that if I want to use LTFTs, then to keep them from affecting the AFR at WOT I would have to fool them into being irrelevant by making them show lean. That way they won't affect the WOT fueling. Or perhaps if the tuning is already pretty close to spot on, then the LTFTs won't be a significant influence anyway.

BTW, a question that I asked has been overlooked I think. Based on my log posted, how does the timing look? Honestly, when I looked at my very first log, I was shocked at how high the timing values were. But as best I can tell there is no *real* KR being logged, so I guess it's OK. But I would be quite a bit relieved just to hear some folks TELL me that it is actually OK.

Thanks.

[Rich Z]

If you already viewed post #38, refresh the page and re-read it (I made a minor correction).

Well, whatever correction you made didn't help to unglaze my eyes. :laugh: I'm still got PE stuck in my head to mean something different then it really does. So it's going to take a little bit for me to "unlearn" that.

Actually, I was stumbling over figuring out what "SOL" stood for ("sheet out of luck" just didn't seem to fit!) until it dawned on me that it HAD to be "Semi Open Loop".

[joecar]

If you already viewed post #38, refresh the page and re-read it (I made yet another minor correction).

[joecar]

Yes, SOL = semi-open loop;

if you're trying to correct VE using wideband, then SOL can make you be the other SOL :)

[joecar]

Spark:

Bret was saying to use A0010 to remove spark timing as boost increases...

I think maybe you would lower the HO and LO tables a little in the high load area and then you would use A0010 to remove more timing (Bret, what would you do...?).


Note also:
the COS allows adaptive spark to continue functioning when a MAF DTC is present (non-COS defaults to LO when MAF DTC is present)
[ adaptive spark = sliding between HO and LO based on KR, look at the pid GM.ASPARK ]
[ HO = high octane spark table, B5913 ]
[ LO = low octane spark table, B5914 ]

[joecar]

Regarding LTFT's
- if VE is correct, then LTFT's should not be a problem;
- STFT/SOL alone will give very good results;
- many people run OL SD;

I like the second point (this also verifies that your wideband is working good (logs will show wideband doing a very tight oscillation around stoich)).

[Rich Z]

Yeah, some of the negative logic aspects of this tuning can bend my mind a little bit.

When looking at the VE table and then the logs, I tried to visualize what it was actually telling me. If the logged map value is greater than 1, then multiplying that to the cell in the VE table is making that value larger. So the larger number is telling the PCM that it should expect MORE air to be in the cylinders so it needs to increase the fuel injector pulse to make it richer. So the VE table cells affected were actually leaner than wanted and we need to make the AFR richer to compensate. This concept took a little bit to sink in.

Honestly, I'm still fuzzy about some of the more basic things because of this possible negative logic. For instance, when looking at the STFTs does a negative value mean the NBs are seeing a rich or lean mixture? Every time I would look at a log with the STFTs enabled I would have to try to correlate that trace with the WB trace to see what the STFTs were doing to it. But since I've got my WB in the passenger side header and it doesn't really coincide with the LABEL for the WB, it kind of twists my brain a bit having to re-figure it out.

Then recently I was reading about O2 switch points, and I hit the brick wall of not having a clue what the CL modes stand for. Sometimes you just run out of time and steam to try to dig down to yet another layer just to figure out what it was you were trying to figure out in the first place.

[hog]

True (you left out some of the Holden/HSV products)...

but when you also include the "plain" engined vehicles models that GM has made, quite a few of those came without a MAF.

But, as you said, by using a MAF, GM must be seeing advantages.

That's a good pic... that has integrated MAF and IAT and what else...?




Bret has a possible advantage for GM using MAF's, to save time by avoiding fine tuning:

Yes, Joe I didn't include any non-GM North America vehicles as I wanted to use accurate data, I'm not well versed with GM/Holden vehicles. And yes, once you get away from the Performance V8 platforms, there are many many non-MAF vehicles. I don't have an opinion either way, MAF vs. Speed Density. I do know of one guy who is running a 703 hp 427 cube LT5 engine using $4000 custom made camshafts(4 of them) that is contemplating switching from Speed Density to Alpha-N. One question, Lingenfelter Performance Engineering sells a 100mm MAF kit, and publishes publicly the MAF tables to use this MAF in any modern performance vehicle. For the LPE twin Turbo 725hp packages, LPE does use this MAF for their 600hp and 725hp twin turbo packages. Any issues with using this MAF? http://www.lingenfelter.com/mm5/merchant.mvc?Screen=PROD&Product_Code=L480000000&Store_Code=LPE&search=maf&filter_cat=&PowerSearch_Begin_Only=&sort=&range_low=&range_high=#.UdG_kYLD9tM Thanks. peace Hog It does appear that I am having issues posting here. I cant space out my post at all, the ENTER key appears to be non functional

[joecar]

If ENTER does not seem to work, try SHIFT-ENTER...

or type your post in a Notepad window and then paste it into the reply/post box.


I sometimes run with MAF, and sometimes without it (lol... I have a specially gutted/nullified MAF body to hold my MAF connector).


I heard the LPE MAF is fine...

their published MAF table would be the starting point correcting the MAF table (MAF performance is sensitive to plumbing and other physical aspects)...


LS1A/LS1B: MAF upper limit is 512 g/s, so to exceed this you will have to scale all air tables (e.g. VE, MAF) and shift all air-referencing tables (e.g. spark);

E38/E67: MAF upper limit is something like 3000 g/s or 4096 g/s, this allows you to run that MAF with boost without having to scale/shift.

[joecar]

This is what LPE state regarding their 100mm MAF (I colored the key points red):



. . .

This MAF sensor will NOT work with stock engine programming and requires recalibration of the factory PCM or ECM. The proper starting MAF sensor curve for most GM applications is supplied with the sensor but you will need EFILive, HPTuners, LS1/LT1/LS2 Edit, TunerCat or other similar software programs to recalibrate the MAF curve or have it done for you by a tuning shop or custom calibration company. The proper curves can be downloaded from the Lingenfelter web site under downloads > product instructions.

. . .

[Rich Z]

If ENTER does not seem to work, try SHIFT-ENTER...

or type your post in a Notepad window and then paste it into the reply/post box.


I sometimes run with MAF, and sometimes without it (lol... I have a specially gutted/nullified MAF body to hold my MAF connector).


I heard the LPE MAF is fine...

their published MAF table would be the starting point correcting the MAF table (MAF performance is sensitive to plumbing and other physical aspects)...


LS1A/LS1B: MAF upper limit is 512 g/s, so to exceed this you will have to scale all air tables (e.g. VE, MAF) and shift all air-referencing tables (e.g. spark);

E38/E67: MAF upper limit is something like 3000 g/s or 4096 g/s, this allows you to run that MAF with boost without having to scale/shift.

So, am I correct in presuming that the MAF and related tables in EFILive for the LS1A/B would still have to be scaled to work with this LP MAF? Not that I am contemplating going that route at this late point in my tuning, just for my own curiosity.

[Rich Z]

Spark:

Bret was saying to use A0010 to remove spark timing as boost increases...

I think maybe you would lower the HO and LO tables a little in the high load area and then you would use A0010 to remove more timing (Bret, what would you do...?).


Note also:
the COS allows adaptive spark to continue functioning when a MAF DTC is present (non-COS defaults to LO when MAF DTC is present)
[ adaptive spark = sliding between HO and LO based on KR, look at the pid GM.ASPARK ]
[ HO = high octane spark table, B5913 ]
[ LO = low octane spark table, B5914 ]

OK, I've got the fueling tables that Bret sent me incorporated into my latest tune where I have it prepped to re-calibrate the VE tables. MAF is again disabled via C2901+ codes and all trims are also disabled. I'll be gradually easing into boost to try not to get any surprises. When I get that dialed in, I'll post the last tune with log to make sure I'm heading in the right direction and then tackle the timing. Bret's suggestion does sound more elegant than the way I had it.

Might take a few days, though, as we've been getting some pretty heavy rains off and on. The weather forecast in this part of Florida for this time of year is "Drought conditions with gradually increasing widely scattered flooding." My wife ran out to do some errands this morning and told me the end of our road was completely under water.

[joecar]

So, am I correct in presuming that the MAF and related tables in EFILive for the LS1A/B would still have to be scaled to work with this LP MAF? Not that I am contemplating going that route at this late point in my tuning, just for my own curiosity.Yes, if you're going above 512 g/s (which, with boost, you will), then you will still have to scale/shift with this MAF (or with any MAF that can go above 512 g/s);

basically (easier said than done, but do-able):
scale: scale down any tables that contain airmass or airflow by some factor (e.g. MAF, VE, IFR... note that IFR contains fuelmass which is proportional to airmass);
shift: shift down any tables that reference airmass or airflow on their axes (e.g. HO/LO/other spark tables);
you can see that this is going to be tedious... and it cannot take into account any tables that are not accessible.


I agree with Bret, you are better of going SD.

[joecar]

Do be careful, keep safe.

[BLK02WS6]

Spark:

Bret was saying to use A0010 to remove spark timing as boost increases...

I think maybe you would lower the HO and LO tables a little in the high load area and then you would use A0010 to remove more timing (Bret, what would you do...?).



The way I do it is to use a naturally aspirated timing table (higher) and then use A0010 to pull from that timing based on boost levels...

His timing is pretty good for his boost levels - I would not worry about it right now - get the fuel right first...

[BLK02WS6]

The reason you use A0010 for timing is this - look at the below timing table:

http://i190.photobucket.com/albums/z135/blk02ws6/screen4.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen4.jpg.html)

as you go through the RPM range, say your boost varied (which it will), you would want the timing to vary with the boost so it is optimum. It would be very hard to map the timing table to go up and down by both boost and RPM - couldn't really get the combination right. But, by using the above table, and the below A0010, you end up with timing varying by both RPM and boost correctly...

http://i190.photobucket.com/albums/z135/blk02ws6/screen5.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen5.jpg.html)

Here is a log of a dyno pull from that car:

http://i190.photobucket.com/albums/z135/blk02ws6/screen6.jpg (http://s190.photobucket.com/user/blk02ws6/media/screen6.jpg.html)

As you can see, the timing varies right along with boost (MAP kpa) through the RPM range. You would be hard pressed to create a table that would vary timing like that using only the high octane table. And the alternative - to just make it one safe value straight across the pull - leaves power and torque on the table... As you can see (not easily on my screenshot) the lowest value during the pull is 17.5* and the highest value is 24.5* - if you made the table so the whole pull was 17.5*, there would be a ton of torque taken off that pull in the beginning and power lost at the end of the pull...

Does that make sense? But, like I said, leave yours alone and we can address that later.

Important question - How much boost are you planning to run?

[joecar]

That makes good sense, thanks.

[Rich Z]

Yes, if you're going above 512 g/s (which, with boost, you will), then you will still have to scale/shift with this MAF (or with any MAF that can go above 512 g/s);

basically (easier said than done, but do-able):
scale: scale down any tables that contain airmass or airflow by some factor (e.g. MAF, VE, IFR... note that IFR contains fuelmass which is proportional to airmass);
shift: shift down any tables that reference airmass or airflow on their axes (e.g. HO/LO/other spark tables);
you can see that this is going to be tedious... and it cannot take into account any tables that are not accessible.


I agree with Bret, you are better of going SD.

Yeah, I hear that....

Wonder how many people bought that LP MAF thinking that it was simply plug and play?

[Rich Z]

Does that make sense? But, like I said, leave yours alone and we can address that later.

Important question - How much boost are you planning to run?

Yes, it certainly does make sense. You explained that pretty well, so it was easy to follow along. And I agree completely with you.

Hopefully I'll get some clear weather over the next few days to do a couple of logging runs to dial in the VE tables.

As for boost, I have 10lb springs in the wastegates. As mentioned earlier, the turbos are rear mounted via a STS system. I don't have any plans to try to go over 10lbs, although my engine is supposed to have been built to handle a lot more. It's based on a RHS block with 6 bolt per cylinder heads. Heck, I think I've only had the throttle at 100 percent twice! Although the engine could handle more than 10 lbs, I'm not sure that I could. Boost does hit pretty hard, and the tuning is apparently far from optimum. I'm pretty sure it will be a very long time before I start to think that the car isn't putting out enough power for me.

But I am being rather conservative about such things, thinking that if I have it over designed, and I don't push it to the limit, perhaps it won't come apart quite so easily on me. :) Of course, very little of what I had originally envisioned actually came to pass with all this.

Thanks again for your help.

[hog]

If ENTER does not seem to work, try SHIFT-ENTER...

or type your post in a Notepad window and then paste it into the reply/post box.


I sometimes run with MAF, and sometimes without it (lol... I have a specially gutted/nullified MAF body to hold my MAF connector).


I heard the LPE MAF is fine...

their published MAF table would be the starting point correcting the MAF table (MAF performance is sensitive to plumbing and other physical aspects)...


LS1A/LS1B: MAF upper limit is 512 g/s, so to exceed this you will have to scale all air tables (e.g. VE, MAF) and shift all air-referencing tables (e.g. spark);

E38/E67: MAF upper limit is something like 3000 g/s or 4096 g/s, this allows you to run that MAF with boost without having to scale/shift.Yes, those tables would be a good starting point. I'm impressed that LPE does include them, and do give a decent explanation of the PCM/ECM tuning that IS REQUIRED for a successful install. I remember years ago when figuring out a MAF table to go from a stock 75mm to a stock 85mm MAF. The numbers would have been nice to have, pre-scaled for the old blackbox PCM. There are many, many makers of cold air intake systems that make no mention of calibration changes that are needed, and many of these CAI's make dramatic changes to air intake tract characteristics. I am trying the Shift Enter and not working. Years ago, LPE did work on some 1995 SUburbans with the 605cid BBC. There were a few different induction variants, one of them included 2 MAFs. That has always piqued my interest. IIRTC they used a signal average bwteen the 2 MAFs then fed that averaged signal to the ECM. One of the ECM's was from a F-body, nnot sure if that's what was used for their dual MAF apps.

[hog]

Yeah, I hear that....

Wonder how many people bought that LP MAF thinking that it was simply plug and play?If they read the advertising/instructions, hopefully not many. If they did, they're leaving lots on the table or not running great at all. Here is the MAF table from LPE for the 100M mAF for the 99-2004 F-body(Camaro/Firebird),Y-body(Vette) and GMT800 truck(99-07) PCM's.

1500
3.18


1625
3.58


1750
4.04


1875
4.57


2000
5.18


2125
5.86


2250
6.63


2375
7.49


2500
8.44


2625
9.50


2750
10.65


2875
11.92


3000
13.31


3125
14.81


3250
16.44


3375
18.21


3500
20.10


3625
22.14


3750
24.33


3875
26.66


4000
29.15


4125
31.81


4250
34.63


4375
37.62


4500
40.79


4625
44.14


4750
47.68


4875
51.41


5000
55.33


5125
59.46


5250
63.80


5375
68.35


5500
73.12


5625
78.11


5750
83.33


5875
88.78


6000
94.47


6125
100.41


6250
106.59


6375
113.02


6500
119.72


6625
126.68


6750
133.91


6875
141.41


7000
149.19


7125
157.25


7250
165.61


7375
174.26


7500
183.21


7625
192.46


7750
202.03


7875
211.91


8000
222.10


8125
232.63


8250
243.48


8375
254.68


8500
266.21


8625
278.08


8750
290.31


8875
302.90


9000
315.84


9125
329.15


9250
342.84


9375
356.90


9500
371.34


9625
386.17


9750
401.39


9875
417.00


10000
433.02


10125
449.45


10250
466.29


10375
483.55


10500
501.23


10625
511.99


10750
511.99


10875
511.99


11000
511.99


11125
511.99


11250
511.99


11375
511.99


11500
511.99


11625
511.99


11750
511.99


11875
511.99


12000
511.99



Be safe where you are weather wise.

[Rich Z]

No joy today for getting the car out. Rained off and on (mostly on) all day. Got the tune loaded in the PCM just waiting for a break. I'm anxious to get moving on this again.

[BLK02WS6]

Its been the same way around here for days... hopefully tomorrow is a bit better for all of us! Sucks to get a day off work and have it rain...

[Rich Z]

Its been the same way around here for days... hopefully tomorrow is a bit better for all of us! Sucks to get a day off work and have it rain...

Yeah, I'm right below Tallahassee. Looks like the entire east coast and all of Florida is getting drenched. And I also live on a dirt road, so with heavy rains, I still have to wait for the road to dry out. Otherwise I'm scraping mud off of the underside of the car when I get back.

But heck, sure beats having wildfires from being too dry.

[BLK02WS6]

That is a good point - a reminder to me that any time I want to bitch about something, there is always someone out there way worse off and I should be counting my blessings instead of bitching!

[Rich Z]

What tables do I need to change in order to convert my Corvette to 4-wheel drive? :)

Rained ALL last night, ALL day, and is still raining right now. I guess just 39 days and 39 nights left to go.

Anyway, I put the trickle charger on the battery, as I don't think I'm going anywhere for a while.

[hog]

True (you left out some of the Holden/HSV products)...

but when you also include the "plain" engined vehicles models that GM has made, quite a few of those came without a MAF.

But, as you said, by using a MAF, GM must be seeing advantages.

That's a good pic... that has integrated MAF and IAT and what else...?




Bret has a possible advantage for GM using MAF's, to save time by avoiding fine tuning:

Joecar, the wires are for the MAF, IAT and humidity sensor. 2 for IAT, 3 for MAF and 3 for humidity.http://i1202.photobucket.com/albums/bb373/Paul_Schermerhorn/GEN5truckmaf.jpg (http://s1202.photobucket.com/user/Paul_Schermerhorn/media/GEN5truckmaf.jpg.html)peaceHog

[Rich Z]

Well, the weather has been pretty crappy, but I have been able to get out a couple of times to do some data logging. Still not where I want to be with it yet, as the VE tables still look pretty lump after multiplying the mapped data into them and then smoothing a bit. I found out that I'm only getting just over 8 lbs of boost with the 10 lb springs in the wastegates. And the boost does start edging down a little bit when throttle is held at WOT. I have no idea what is going on with that. Boost comes on pretty hard and reaches it's limit plateau fairly quickly.

Ah well, I'll attach the last log file I took in case anyone wants to eyeball it for me.

If the rains would let up I'd like to get this fueling stuff out of the way. But it is what it is, I guess.

Thanks...

[Rich Z]

Had a break in the rain on Sunday, so I took the car out for a short run. Pushed it into boost a couple of times and then came on home to look over the log.

And I'm confused. It actually looks like things are worse some places, and better in others. I'll attach the tune and log.

In the log from frame 2680 to 3440 it looks like I'm running too lean. Then in most instances when I have zero throttle but VSS > zero, it runs pretty rich. Especially when I run up the RPMs and then just put the tranny into sixth gear and use engine breaking to bring down my speed.

So are these instances of my coasting down from speed in gear screwing up my map values for when I use the map chart to adjust the VE tables? Do I need to change how I am driving the car during data logging, or do I need another entry in the filter for the map to remove those coasting frames? :wallbash:

[ddnspider]

Had a break in the rain on Sunday, so I took the car out for a short run. Pushed it into boost a couple of times and then came on home to look over the log.

And I'm confused. It actually looks like things are worse some places, and better in others. I'll attach the tune and log.

In the log from frame 2680 to 3440 it looks like I'm running too lean. Then in most instances when I have zero throttle but VSS > zero, it runs pretty rich. Especially when I run up the RPMs and then just put the tranny into sixth gear and use engine breaking to bring down my speed.

So are these instances of my coasting down from speed in gear screwing up my map values for when I use the map chart to adjust the VE tables? Do I need to change how I am driving the car during data logging, or do I need another entry in the filter for the map to remove those coasting frames? :wallbash:

It looks like you're running rich at high RPM in frames 9872-9882. Your IAT's are also getting rather high during a pull at 120*F+. What do you have for an intercooler setup? I'm honestly shocked that the car isn't seeing knock retard with that much timing and those IAT's. Coincidentally, what size turbo's are your rear mounts? Any chance theyre undersized? If you are outside the efficiency range of the turbos that may be where some of the intake temps are coming from. My IAT's usually only raise 5-10*F during a single gear pull and I am running ~13 psi or more.

You're also lean at mid map high RPM values like in frames 8800-8840, and looking at your logs look at GM.AFR, youre commanding AFR of 14:1 or leaner, because your PE map threshold is set to 110kPa so PE isnt kicking in yet. I would try and not do the coasting thing or at least filter it out and see how your data changes. If you still a dramatic change in BEN's, then maybe you should exclude the coasting.

I am also in the process of tuning my boosted LS1 and am in FL. The weather is making is interesting to try and get some good tuning time lol.

[Rich Z]

It looks like you're running rich at high RPM in frames 9872-9882. Your IAT's are also getting rather high during a pull at 120*F+. What do you have for an intercooler setup? I'm honestly shocked that the car isn't seeing knock retard with that much timing and those IAT's. Coincidentally, what size turbo's are your rear mounts? Any chance theyre undersized? If you are outside the efficiency range of the turbos that may be where some of the intake temps are coming from. My IAT's usually only raise 5-10*F during a single gear pull and I am running ~13 psi or more.

You're also lean at mid map high RPM values like in frames 8800-8840, and looking at your logs look at GM.AFR, youre commanding AFR of 14:1 or leaner, because your PE map threshold is set to 110kPa so PE isnt kicking in yet. I would try and not do the coasting thing or at least filter it out and see how your data changes. If you still a dramatic change in BEN's, then maybe you should exclude the coasting.

I am also in the process of tuning my boosted LS1 and am in FL. The weather is making is interesting to try and get some good tuning time lol.

The turbos came from Turbos Direct. I asked them about the turbos and he said "Looks like they are T3/T4. 57 trim on the comp side, and stage 3 on the turbine side. Each one is good for about 425-450hp at the crank."

The intercooler is a single front mounted affair that sits in front of the radiator.

I've been looking over the log and it appears to me that the coasting in gear is pushing the kPa way down, so would this really be an issue? I thought I had PE disabled as well as DFCO. But heck, I've been trying so many different things that I'm losing track now.... :(

Yeah, I checked to make certain that KRs were enabled. The only place I see any KR in this log is when I was just playing around with WOT in sixth gear at low speeds. And even then, I'm not sure it's *real* KR even then.

Thanks for your help....

[ddnspider]

I wonder if youre not choking the turbos with that large of a motor. What size is the FMIC? 3" or 4"? If I were you i would filter out the coasting and see if that helps clean up your BEN's. Hope it goes well for you, and stay dry.

[joecar]

It seems to me that your VE table range [400-2400 rpm, 15-50 kPa] is on the low side (it falls sharply from the rest of the table).

[ddnspider]

It seems to me that your VE table range [400-2400 rpm, 15-50 kPa] is on the low side (it falls sharply from the rest of the table).Joe thats funny that you mentioned that. I borrowed Rich's VE table as a starter for mine when I started my AutoVE, and I had to add ~50% to the numbers in order to get my A/F dialed in and the car running.

[Rich Z]

I wonder if youre not choking the turbos with that large of a motor. What size is the FMIC? 3" or 4"? If I were you i would filter out the coasting and see if that helps clean up your BEN's. Hope it goes well for you, and stay dry.

Well, bear in mind that I've been lied to a LOT when I was having this build done, so anything is possible. Supposedly those turbos were recommended for the 427 engine. I actually had smaller ones on the LS6 engine and the turbos now on it were recommended by Turbos Direct with the knowledge of that new engine.

Sorry, you lost me with "FWIC". I can't figure out what that means. "Something" InterCooler, perhaps?

What would be the best method to use to filter out the coasting without affecting any other frames?

Thanks....

[Rich Z]

It seems to me that your VE table range [400-2400 rpm, 15-50 kPa] is on the low side (it falls sharply from the rest of the table).


Joe thats funny that you mentioned that. I borrowed Rich's VE table as a starter for mine when I started my AutoVE, and I had to add ~50% to the numbers in order to get my A/F dialed in and the car running.

So what am I doing wrong? I've been doing the logging runs and simply copying and pasting (with multiply) to get the VE tables where they are now. So what am I overlooking that I need to change to make that give me accurate data?

[joecar]

PE is enabling at 110 kPa (as suggested by BLK02WS6/Bret);

B3647: I would make the 90 and 95 kPa columns the same as the 100 kPa column, and ramp up from 80-90 kPa.

[joecar]

For your next log:
- delete GM.MAFFREQ, GM.MAPBOOST_DMA,
- add GM.EQIVRATIO, EXT.WO2EQR1,
(your pid channel count will now be at 22).

[ddnspider]

Well, bear in mind that I've been lied to a LOT when I was having this build done, so anything is possible. Supposedly those turbos were recommended for the 427 engine. I actually had smaller ones on the LS6 engine and the turbos now on it were recommended by Turbos Direct with the knowledge of that new engine.

Sorry, you lost me with "FWIC". I can't figure out what that means. "Something" InterCooler, perhaps?

What would be the best method to use to filter out the coasting without affecting any other frames?

Thanks....

I find it difficult to believe that twin T3/T4's would be properly suited to a twin rear mounted 427 ci setup. It sounds like you've had a rough past with the car so at least its running and driving. FMIC is front mount intercooler, I am assuming that it is a 2 in- 1 out style, but is it 3" thick or 4" thick? The only reason I ask is that I saw quite a difference in my iat's once I setup my intercooler properly and gave it the airflow it needed. FL weather can definitely put a hurting on temps in general.

[EagleMark]

What would be the best method to use to filter out the coasting without affecting any other frames?

Thanks....Did you disable DFCO and Decel Enleanment? That will cause a Rich deceleration.

Filter? How about TPS% less then 1 or 1.5%?

[Rich Z]

PE is enabling at 110 kPa (as suggested by BLK02WS6/Bret);

B3647: I would make the 90 and 95 kPa columns the same as the 100 kPa column, and ramp up from 80-90 kPa.

Umm, I'm using the B3647 table as was suggested by Bret as well. Did I do that incorrectly?

[Rich Z]

For your next log:
- delete GM.MAFFREQ, GM.MAPBOOST_DMA,
- add GM.EQIVRATIO, EXT.WO2EQR1,
(your pid channel count will now be at 22).

OK, I've made those changes. Raining again, so maybe I can get out tomorrow. But honestly, I guess I want to have a clear plan in place anyway, so I'm not in any hurry. There seems to be some confusion on my part about that B3647 table being set up correctly.

[Rich Z]

Did you disable DFCO and Decel Enleanment? That will cause a Rich deceleration.

Filter? How about TPS% less then 1 or 1.5%?

I believe I have DFCO disabled. Not sure about the "Decel Enleanment" as I was under the impression that this is what DFCO does. What table(s) do I need to look at for that?

Will that filter change also filter out low speed driving? Reason I ask is because I live off of a dirt (sand) road, and usually just coast down it at idle or barely above to keep from kicking too much sand up underneath the car. I'm thinking maybe the averaging of both this low speed driving and coasting down from a high RPM run is causing the confusing VE figures I'm getting from my map data.

[ddnspider]

I believe I have DFCO disabled. Not sure about the "Decel Enleanment" as I was under the impression that this is what DFCO does. What table(s) do I need to look at for that?

Will that filter change also filter out low speed driving? Reason I ask is because I live off of a dirt (sand) road, and usually just coast down it at idle or barely above to keep from kicking too much sand up underneath the car. I'm thinking maybe the averaging of both this low speed driving and coasting down from a high RPM run is causing the confusing VE figures I'm getting from my map data.

That filter change will filter out anything where the throttle blade is less than 1% I.e. during decel, not that it would also filter out idle cells. Can you just put the car in neutral when you want to slow to a stop and avoid kicking up dirt?

[Rich Z]

That filter change will filter out anything where the throttle blade is less than 1% I.e. during decel, not that it would also filter out idle cells. Can you just put the car in neutral when you want to slow to a stop and avoid kicking up dirt?

I guess I didn't explain that very well. When I pull out of my driveway, I pull onto a dirt road for about a quarter of a mile or so till I get to pavement. I only drive at 10 mph or less, which means I pretty much have the car at idle, so the throttle position is at zero percent or maybe just barely pressure on the gas pedal. Will it be a problem to filtering out those frames too trying to dial in the VE table?

The deceleration issue is NOT while I am on that dirt road. Heck, I'd be wrapped around a tree for certain going into boost on a dirt road. :)

But yeah, I may try the filter on the currently collected data and then next times I am out to just put the car in neutral and stop using engine braking to slow down after going into boost.

As for the turbos, how could I test to see if they are just going into saturation and not able to keep up with the engine needs? Or is it just that the wastegates are activating at 8 lbs of boost instead of the 10 lb ratings of the springs? Looking at the log, the boost does seem to just go flatlined at around 8 psi. I bought one of those manual boost controllers that I could plumb into the vacuum line right before the "T" running to the wastgates. I'm thinking that might tell me something about what is going on. Not that I'm not getting enough power, but it just feels like the engine isn't responding to more gas pedal after the 8 psi of boost is reached. The car is still accelerating, of course, but it feels like it will continue doing that with no change in acceleration whether the gas pedal is at 75 percent or 100 percent. I think you can see that in my log between frames 9850 and 9880.

Thanks...

[ddnspider]

Just because you're only making 8 psi instead of 10 isn't why I think the turbos are too small. You may just have an efficient setup or have losses due to the rear mount piping. Where are the waste gate vacuum lines referenced to, the turbos or the intake manifold? Since you got these turbos from a company, can they give you a compressor map? We can plot out based on your boost and estimated airflow if you are in the efficiency range of the turbos. One hint of a mismatched boosted setup is seeing large jumps in iat's when in boost, but that could also be attributed to your intercooler setup which is why I asked. It's like a positive displacement blower, when they go outside their efficiency range they simply generate extra heat and shoot up the iat's.

Ps when we get our setups finished we should meet up and compare! Haha

[EagleMark]

It seems to me that your VE table range [400-2400 rpm, 15-50 kPa] is on the low side (it falls sharply from the rest of the table).Joe may have found this earlier, has nothing to do with mid range or boost, just your deceleration issue. Just had time to look at your .tun. Your VE table is just wrong there.

Take a look at this .tun Main VE in 3D and compare it to the one you loaded, all I did was straighten out that decel area. The VE table has to be somewhat smooth, just because you are data logging and see what cell your in or use your log to adjust that cell, does not mean it's right. If in one cell it is interpolated to all surrounding cells.

HTH! :grd:

[joecar]

Umm, I'm using the B3647 table as was suggested by Bret as well. Did I do that incorrectly?


OK, I've made those changes. Raining again, so maybe I can get out tomorrow. But honestly, I guess I want to have a clear plan in place anyway, so I'm not in any hurry. There seems to be some confusion on my part about that B3647 table being set up correctly.

Bret set it up correctly... l like to see a little richer as load gets to 90 kPa (just to be safe during tuning).

[Rich Z]

Just because you're only making 8 psi instead of 10 isn't why I think the turbos are too small. You may just have an efficient setup or have losses due to the rear mount piping. Where are the waste gate vacuum lines referenced to, the turbos or the intake manifold? Since you got these turbos from a company, can they give you a compressor map? We can plot out based on your boost and estimated airflow if you are in the efficiency range of the turbos. One hint of a mismatched boosted setup is seeing large jumps in iat's when in boost, but that could also be attributed to your intercooler setup which is why I asked. It's like a positive displacement blower, when they go outside their efficiency range they simply generate extra heat and shoot up the iat's.

Ps when we get our setups finished we should meet up and compare! Haha

The wastegates are referenced at the back of the intake manifold.

I'll have to ask Turbo Direct about that compressor map and see what they say.

Heck, I forgot to go over to the garage to measure the output pipe of the intercooler. But seems to me it should be around 3.5 to 4 inches. That's the coupling sizes I was using getting the airbridge straightened out to go over the radiator.

http://www.corvetteflorida.com/pics/airbridge_new_03.jpg

But in any event concerning the turbos, what I have is what is going to have to stay there till they need to be replaced due to wear and tear. I've had to go WAY over budget on the car to keep from just giving up and scraping it, so at this point my goal is to get the tuning done enough so that I can finally after a few years of this nightmare, be able to just enjoy driving it.

Right now the car really is driveable with just a few rough edges. And it actually drives darn well. But I want to make sure I'm not doing something not just wrong, but possibly damaging to my engine.

What part of Florida are you located in? I sure could have used a hand several times working on fixing my car a while back. :)

[Rich Z]

Joe may have found this earlier, has nothing to do with mid range or boost, just your deceleration issue. Just had time to look at your .tun. Your VE table is just wrong there.

Take a look at this .tun Main VE in 3D and compare it to the one you loaded, all I did was straighten out that decel area. The VE table has to be somewhat smooth, just because you are data logging and see what cell your in or use your log to adjust that cell, does not mean it's right. If in one cell it is interpolated to all surrounding cells.

HTH! :grd:

OK, thanks! I can see what you are talking about with that VE table. Quite honestly I've done the VE stuff a LOT of times now, and in most instances smoothed the table after applying the data from my map data. I've tried both automatic smoothing, and hand smoothing, and sometimes smoothed the HELL out of the table. But it just puzzled me why when I would make yet another data logging run and apply the map data, I'm right back to having humps and valleys in the VE table again.

So what is REAL? Is the best quesstimate of what the VE table SHOULD be as a perfectly smooth surface what the engine NEEDS to run properly? Or is the actual data being gathered via the map data showing the difference between what the VE table is telling the PCM is real and what the wideband is then feeding back what IT thinks is real? Does an engine in reality actually have humps and valleys in the data that the VE table is supposed to represent? If not, then what am I doing wrong to make them show up? But on the other hand, if the data being gathered is actually the real world, why would it be best to smooth it over with false data instead?

So if I load that new VE table into my PCM tomorrow and take it out for a drive and the map data again produces humps and valleys when merged with the VE table data, what does that mean to me? Am I just doing something wrong with how I am collecting the data? Am I applying the data collected in the map incorrectly? Am I just trying to get it TOO perfect and don't recognize the point that I need to just stop and move on?

The car actually does drive pretty well like it is. So should how it FEELS, as long as I'm not doing something stupid, be the real yardstick I should be using?

Thank you all for your help with this.

[Rich Z]

Bret set it up correctly... l like to see a little richer as load gets to 90 kPa (just to be safe during tuning).

Thanks Joe. I'll look over that table and modify it a bit. I've been looking over the log file and it does appear to be going lean right in that area, so I would rather play it safe. Should I still keep the PE kicking in up high or would it be best to bring that down into the NA area a little bit as well? Without considering FI, it seems to me that PE would be enabled somewhere below 105 kPa anyway, wouldn't it?

[ddnspider]

The wastegates are referenced at the back of the intake manifold.

I'll have to ask Turbo Direct about that compressor map and see what they say.

Heck, I forgot to go over to the garage to measure the output pipe of the intercooler. But seems to me it should be around 3.5 to 4 inches. That's the coupling sizes I was using getting the airbridge straightened out to go over the radiator.

http://www.corvetteflorida.com/pics/airbridge_new_03.jpg

But in any event concerning the turbos, what I have is what is going to have to stay there till they need to be replaced due to wear and tear. I've had to go WAY over budget on the car to keep from just giving up and scraping it, so at this point my goal is to get the tuning done enough so that I can finally after a few years of this nightmare, be able to just enjoy driving it.

Right now the car really is driveable with just a few rough edges. And it actually drives darn well. But I want to make sure I'm not doing something not just wrong, but possibly damaging to my engine.

What part of Florida are you located in? I sure could have used a hand several times working on fixing my car a while back. :)

Hey as long as the car is together now, you may as well enjoy it until something breaks :thumb_yello: It would be worth trying to get the compressor maps, just so you know where you are.

I think you said you were near tallahassee? I'm about 3 hours south of you near orlando.

[EagleMark]

OK, thanks! I can see what you are talking about with that VE table. Quite honestly I've done the VE stuff a LOT of times now, and in most instances smoothed the table after applying the data from my map data. I've tried both automatic smoothing, and hand smoothing, and sometimes smoothed the HELL out of the table. But it just puzzled me why when I would make yet another data logging run and apply the map data, I'm right back to having humps and valleys in the VE table again.

So what is REAL? Is the best quesstimate of what the VE table SHOULD be as a perfectly smooth surface what the engine NEEDS to run properly? Or is the actual data being gathered via the map data showing the difference between what the VE table is telling the PCM is real and what the wideband is then feeding back what IT thinks is real? Does an engine in reality actually have humps and valleys in the data that the VE table is supposed to represent? If not, then what am I doing wrong to make them show up? But on the other hand, if the data being gathered is actually the real world, why would it be best to smooth it over with false data instead?

So if I load that new VE table into my PCM tomorrow and take it out for a drive and the map data again produces humps and valleys when merged with the VE table data, what does that mean to me? Am I just doing something wrong with how I am collecting the data? Am I applying the data collected in the map incorrectly? Am I just trying to get it TOO perfect and don't recognize the point that I need to just stop and move on?

The car actually does drive pretty well like it is. So should how it FEELS, as long as I'm not doing something stupid, be the real yardstick I should be using?

Thank you all for your help with this.Yes there's a point where you need to stop and move on. Especailly in FL with daily changes in tempos and humidity. In the end a VE should be fairly smooth but does not have to be perfect. But during data if you have peaks and valleys like you do and your only getting data for the valley, which I think is what is happening here? Then the valley get's bigger to get the correct interpolation number for the area...ie.. the peak is making valley bigger!

Look at this part of VE, I think it's correct and you have been getting data here:
http://forum.efilive.com/attachment.php?attachmentid=15517&d=1373982492

Now on decel the data is going to 20 MAP column and creating a valley to compensate for the peak in 15 MAP column.
http://forum.efilive.com/attachment.php?attachmentid=15516&d=1373982490

Drag down the peak in 15 MAP column that is not getting data correction! Use the visual 3D MAP to make it look correct. Then when data logging if it is in 20 MAP well the correction will not be as extreme!

[joecar]

Thanks Joe. I'll look over that table and modify it a bit. I've been looking over the log file and it does appear to be going lean right in that area, so I would rather play it safe. Should I still keep the PE kicking in up high or would it be best to bring that down into the NA area a little bit as well? Without considering FI, it seems to me that PE would be enabled somewhere below 105 kPa anyway, wouldn't it?NA: PE would enable by throttle only (when MAP is above 20 kPa).

FI: Below 105 kPa use the last 3 columns of B3647 (set them sufficiently rich), above 105-110 kPa let PE enable (as Bret showed).

[joecar]

Smoothing:
- do only minimal smoothing (usually by hand in local regions, not globally),
- flatten out any spike (positive or negative), spikes can't physically exist,
- smooth any sudden steps (by extrapolating the good side of the step to the other side), steps can't exist physically,
- minor sized ridges/ripples are ok (usually indicate resonances in intake/exhaust),
- after smoothing, if the next log/map brings back a spike/step feature, examine it closely and figure out why.


The key is: VE can't jump/step/spike suddenly, it has to flow from each cell to the surrounding cells (minor sized ripples/ridges fit this).

[Rich Z]

Rats... I've been using 93 octane non ethanol gasoline all along with the car as only one gas station I know of around here has it. I wanted to keep that a constant rather than using variable types of gasoline, but I just learned that the gas station dropped the non-ethanol down to 91 octane. So I either need to get this done with the gasoline remaining in my tank, or go to the 91 octane non ethanol or 93 ethanol gasoline and I guess start over from scratch. How much will that screw up things for me at this point?

Darn rain kept me from being able to put more time into this to have this done by now, and now I've got this curve ball thrown at me.

But I guess I was going to reach this point sooner or later anyway. Eventually I would HAVE to use ethanol gasoline anyway, or plan on not driving that car further than a half tank radius from the only station the 93 non-ethanol gasoline was available from.

Always something......

[joecar]

Gasoline:

there are cheap gasoline test kits, they tell you what % alcohol is in your gas, then you can set B3601.

[Rich Z]

Gasoline:

there are cheap gasoline test kits, they tell you what % alcohol is in your gas, then you can set B3601.

How is this problem of different types of gasoline handled by a stock tune?

[joecar]

How is this problem of different types of gasoline handled by a stock tune?Only the later ones...

some of the later vehicles have a flex fuel sensor or a virtual flex-fuel sesnor...

but the earlier ones (yours and mine), we have to manually monitor the gasoline we run.

[EagleMark]

O2 sensor. If your dialed in a tune on non ethanol and then add E fuel the fuel trims raise. O2 sensor adjusts to Stoich of fuel.

[Rich Z]

O2 sensor. If your dialed in a tune on non ethanol and then add E fuel the fuel trims raise. O2 sensor adjusts to Stoich of fuel.

Well, I guess I'm going to have to do what I can with whatever gasoline is remaining in my gas tank, re-enable the fuel trims when I go to the diluted gasoline, and call it a day on that aspect of the tuning. So will a tune on non-ethanol gasoline produce a leaner or richer mix when I switch to ethanol gas? I think the mixture is less than 10 percent around here.

[ddnspider]

I believe you will be leaner because you don't have the same gasonline content as the non-ethanol gas, meaning you will have positive fuel trims.

[joecar]

Stoich AFR's:

E00 = 14.6
E10 = 14.2
. . .
E85 = 9.7

(E00 is shorthand for straight gasoline)


So you can see that as the alcohol content increases the AFR ratio decreases, so you need to add fuel, this is done by editing B3601 (if your ECM does not handle flex fuel).


If you let the trims handle it, then you will see incorrect fueling when going to PE (positive trims are added, negative trims are not).

If you're running OL then you're not trimming so you will have to edit B3601.

[BLK02WS6]

Sorry I haven't been around - busy life with 2 little ones and work...

The above discussions are why I tune using lambda instead of AFR - takes into account blended fuels when correcting tables. When I finish, if trims are posative when I re-enable them, I adjust B3601 (usually to 14.2 because E10 is pretty much everywhere here).

[EagleMark]

Years ago I would notice BLM (LTFT in OBDI) were consistently adding fuel and I found the Desired AFR or Stoich setting was a perfect fix for this. At the time I thought it was a cheat when actually that is the first thing you should start with!

Joe talked me into Lambda and at first I had a hard time wrapping me head around it? Then a little more knowledge proved that AFR is so wrong... Lambda is so accurate and simple!

There's very few people who consistently go out of there way to run Non Ethanol that starting a tune at 14.13 is the way to go.

[Rich Z]

Hit a slight snag the other day.

I had the car out on Wednesday doing some more logging and when I had it in some low level boost trying to get some map cells populated, I noticed a, well, engine "burp" is about the best way to describe it. Never had that before, so it did kind of unnerve me a bit. I thought, "NOW what?" But the car got me back home OK. I actually did another tune and took the car out again, but didn't go into boost, and the car drove OK, but seemed rather rough at idle. And the timing looks a bit squirrelly too. Backing up a little bit, when I loaded that tune (#0027) I was pulling off of the garage apron and noticed that the oil pressure gauge was reading ZERO. Yeah, THAT caught my attention! But then I noticed that all of the gauges were dead. So I pulled back onto the apron and found out that I couldn't get the EFILive box to talk to my PCM. Sheesh.... So I just shut everything down, disconnected the V2 cable and rebooted the PC, and luckily I could then talk to the PCM again. But odd thing is that the gauges wouldn't come back until I reloaded that same tune again. :shrug01:

But the car seemed to run OK after I took it out again, but I didn't run it up into boost at all, which is probably a good thing.

Later on in the evening, I was looking over the log for that run where I had the hiccup, and I noticed something odd right where the hiccup should have been in the log.

http://www.corvetteflorida.com/pics/boost_failure_07172013_01.jpg

Looked like timing advance just gave up and dropped to zero. This appeared to correspond ALMOST with a bump in the engine rpm trace, but not exactly. It seems to lead it a bit. The drop in advance seemed to line up with a slight rise in RPM, and then it dropped down. Then I noticed that the boost reading from the MAP sensor dropped like a rock right after that dip in spark advance. The more I thought about it the more it seemed likely that I had a boost pressure leak suddenly show up. But it is kind of a puzzle why the timing advance drop seemed to precede the boost drop out.

So today (Thursday) I popped the hood and started poking around. First thing I noticed was that it appeared that the airbridge had been rubbing on the underside of the hood again. Then I noticed something was different about the airbridge plumbing.

Here's a pic of the airbridge plumbing right after I got it put together.
http://www.corvetteflorida.com/pics/airbridge_new_03.jpg

And here we have what I noticed today.
http://www.corvetteflorida.com/pics/boost_failure_07172013_02.jpg

That gap showing the aluminum tube between the two clamps was completely gone. And the bottom of the airbridge had come loose completely of the MAF sensor housing.

http://www.corvetteflorida.com/pics/boost_failure_07172013_03.jpg

Sigh......

So I've got the airbridge and MAF sensor pulled out of there now. One thing I did find out is that the reducing coupler between the throttle body and the aluminum tube going to the air bridge is really not rated for boost. Summit's website didn't indicate that and I only found out by going to other sites trying to figure out what the thickness and number of plies are in that coupler. Apparently there are NO plies and it is just simply a single ply of rather flexible silicon. I thought it seemed rather soft when I installed it, and my guess is that it is way TOO soft and it was possibly ballooning out under pressure, pulling on the airbridge. But how that aluminum tube got sucked further into that coupler kind of has me baffled.

And this might even explain why I wasn't able to get over 8 lbs of boost out of those 10 lb wastegate springs.

In any event, I've got a new coupler on order that is supposed to be designed for boost conditions, so I guess the car is dead in the water for a bit waiting for that part to show up. In the meantime I'm going to cut away that part of the MAF housing that is supposed to fit into a notch on a coupler or airbridge so that the airbridge fits more snuggly on that end. I was actually looking for an aluminum MAF body, but couldn't find anything that looked like it would be an easy replacement. I'm not sure if that plastic MAF housing is getting too pliable when it gets hot, and therefore allowing the lower part of the airbridge to slip off of it. Anyway, all of the aftermarket stuff I looked at was either too long, or too wide, or both, which would mean too much fabrication to get it all back in place. So I'll just have to see if what I monkey around with when the new coupler comes in holds up well enough or not.

[joecar]

Rich, thanks for posting that... it shows the importance of thinking and visual inspection as the first steps of troubleshooting.

[ddnspider]

Isn't modifying cars a blast :) First thing I thought of when I read the first paragraph was that you had a coupler blow LOL. I've had a car shut off during a pull when a coupler blew off lol. At least it wasn't the motor, right?

[EagleMark]

First thing I thought of when I read the first paragraph was that you had a coupler blow LOL. I've had a car shut off during a pull when a coupler blew off lol. One time blow off valve? :muahaha:

[Rich Z]

Isn't modifying cars a blast :) First thing I thought of when I read the first paragraph was that you had a coupler blow LOL. I've had a car shut off during a pull when a coupler blew off lol. At least it wasn't the motor, right?

Yeah, that did cross my mind when that hiccup happened. But when the car continued to drive OK after a few minutes, I figured the engine was OK.

I really think most of my problem is that darned plastic airbridge. It just gets pliable when hot. Which allows things to move around that you really don't want to move around. I'd like to get one of those gopro camcorders and see if I could video it while driving under boost. It probably blows up like a balloon. The place I bought it from said it will hold 20+ lbs of boost, but I doubt it will do that if it's hot. I've heated it up and then tightened down the clamps, but I'm afraid to REALLY crank down on them. Particularly on the end that wraps around my MAF sensor housing. The housing is only plastic itself. I actually have one of those aluminum BBK airbridges that I used to have on the car, but for some reason after the engine upgrade, it just no longer fits properly. Or at least I haven't found the magic combination of swear words yet. Maybe I'll take another look at it while I have the plastic airbridge off. I would REALLY like to have metal plumbing from intercooler to throttle body. The problem is getting the plumbing over the radiator upper support. I could get four inch tubing and figure out the bends I need, but that just won't fit between the hood and the radiator support. I really don't want to drop down to three inch plumbing.

Maybe I need to put some modelling clay on top of that radiator support and close the hood on it to try to figure out exactly how much clearance I have.

Yeah, once you go past just a single mod on your car, the interactions between multiple mods can throw some daunting challenges at you to try to get it all PHYSICALLY working together properly. Each mod is designed apparently with the premise that it will be the ONLY mod on the car, with no allowances made for any other mod that might be in place.

[ddnspider]

One time blow off valve? :muahaha:

hahahah niiiice.


PS.....I just did some tuning and I recreated your "burp" LOL Coupler popped off but enough air was still going through the MAF to keep it running. On the plus side I saw a nice drop in MAF Hz since I ran more 4" tubing in front of the MAF....maybe there is hope for me yet. Now if I could just keep the couplers together :)

[Rich Z]

hahahah niiiice.


PS.....I just did some tuning and I recreated your "burp" LOL Coupler popped off but enough air was still going through the MAF to keep it running. On the plus side I saw a nice drop in MAF Hz since I ran more 4" tubing in front of the MAF....maybe there is hope for me yet. Now if I could just keep the couplers together :)

One of the guys on my own forum told me that some of the turbo diesel guys he knows will use hairspray when putting couplers together. The hairspray acts as a lubricant while wet, but then dries as an adhesive. Never tried it myself, personally, but thought it was worth mentioning here.

[EagleMark]

That may work? It's an old school dirtbike trick to get hand grips on the handlebars as well.

[ddnspider]

Yea I've heard of the hairspray trick, just never tried it either. I was a bit impatient to finish tuning so I didnt have any 4" t-bolt clamps handy either, so worm clamps it is until I can get some.

Anyways, I don't mean to hijack your thread. I have my own thread of misery :wallbash::tongue:

[Rich Z]

Yea I've heard of the hairspray trick, just never tried it either. I was a bit impatient to finish tuning so I didnt have any 4" t-bolt clamps handy either, so worm clamps it is until I can get some.

Anyways, I don't mean to hijack your thread. I have my own thread of misery :wallbash::tongue:

No worries. It's all good....

[hog]

It helps to "rough up" the shiny plastic MAF ends, you can even "machine" shallow grooves. It doesn't take much, just needs something to grip onto.peace Hog

[Rich Z]

OK, got the coupler in that I was waiting for and got the airbridge back on. Of course, it's been raining here EVERY day and doesn't look like it will break any time soon.

First thing I need to do is to take a short run without going into boost so I can heat up the plastic airbridge, and then retighten the T-bolt clamps while it is hot to make sure it snugs up.

Second thing I want to do is to go ahead and bite the bullet and fill up the gas tank with E10. What do I need to change in the tuning for this fuel change?

I'm aware that B3601 needs to be changed. E10 means an AFR of 14.13 correct?

What about any of the PE tables?

Does anything having to do with my wideband need to be changed?

Anything else?

Thanks!

[joecar]

E10: set B3601 to 14.1-14.2... no other change needed.


Your wideband AFR now has to be multiplied by (14.1/14.7)... but if you're using Lambda then you don't need to do anything.

( Lambda is regardless of a fuel's stoich AFR... at the stoich AFR, Lambda equals unity )

[ddnspider]

I must be living under a rock. So if you get regular 93 octane pump gas, because it contains some % of Ethanol, you set B3601 to ~14.2 as your stoic point instead of 14.63?

[hog]

I must be living under a rock. So if you get regular 93 octane pump gas, because it contains some % of Ethanol, you set B3601 to ~14.2 as your stoic point instead of 14.63?
You change the Stoich point in the ECM/PCM anytime you run E10 fuel, premium or not. But most don't worry about it as the OEM's don't, its a small difference, most wouldn't notice the difference. E10 has been in my area since the early 90's and all stoich points in all PCM's are still left at 14.6:1.

[joecar]

E00 to E15: the PCM can handle it using trims (i.e. you will see large positive LTFTs).

[ddnspider]

E10 is regular pump gas that has an Ethanol content whereas E00 has no Ethanol additive?

[Rich Z]

E00 to E15: the PCM can handle it using trims (i.e. you will see large positive LTFTs).

Yeah, and because of those positive LFTFs, that's why I want to do the tune now using E10 fuel specs. I want to try enabling the LTFTs during normal driving but don't want the positive fuel trims to muck up WOT. I'm thinking keeping the LTFTs as close to zero as I can, but a bit on the minus side might be what I have to do. Yes/no? Sometimes the flipping between positive and negative logic in this stuff confuses the hell out of me.

I believe my wideband (serial LC-1) is using EQ, so I guess I'm OK with that. No PE offsets or multipliers need to be monkeyed with?

I'm still waiting for my road to dry out. Maybe tomorrow, if we don't get any more rain, I can run out for a bit.

I think I've still got just under a half tank of E00 93 in the gas tank, so I will likely drive the car around to use that up and then fill up with E10 93.

So since the wideband and B3647 are using EQ, will I really expect to see much change in the maps for B0101 and A0009? Do I need to wait through a couple fillups of E10 before resuming logging?

[Rich Z]

E10 is regular pump gas that has an Ethanol content whereas E00 has no Ethanol additive?

That is the way I understand it. E10 means 10 percent ethanol content. E00 means zero percent ethanol content.

I guess I could use shorthand such as E10-93 to indicate 10 percent ethanol, 93 octane.

[Rich Z]

Update:

Been raining most of the time since I last posted, but I did get to take the car out and rill the gas tank with E10 93 octane. Started re-calibrating the VE table.

I pushed it into boost a bit and got a hiccup again. Not sure what caused it this time, as the airbridge was still securely in place when I got back.

While doing some digging around, I found out that the way my wastegates are hooked up to the intake manifold is not recommended by Tial nor a couple of other places I talked to. Push come to shove, I am completely redoing the wastegates and plumbing. Going to drill and tap holes for fittings in the compressor housings and run directly from each turbo to it's respective wastegate. I'm also going to 14 lb springs to see if perhaps I can get boost over the 8 psi or so that has been a cap to me. According to the engine builder, it should handle at least 25psi, so I'm still being somewhat conservative (relatively speaking) about this. So anyway, waiting for the parts to come in before I take the turbos apart to start on this.

While poking around in my tune to see if I could find anything else that might be related to that above mentioned hiccup, I noticed something that has me a bit confused. I thought maybe a misfire condition had maybe caused the hiccup, but I didn't get any error codes indicating that. Well, could someone please take a look at tables C5621, C5622, C5623, C5626, and C5627 for me (at the beginning of this thread) and tell me what you think? Has misfire detection been completely disabled in my tune? I compared these tables with a stock C5 Z06 tune, and they are definitely different.

Maybe there was a good reason that this was done, but I guess I'm uncomfortable thinking that I might have misfires going undetected.

[ddnspider]

Alot of people disable misfire detection on larger c.i. motors with cams and valvetrain to avoid falsely tripping misfire detections.

As for your wastegate referencing, how is it referenced? If you reference it to the compressor housings, you will lose boost due to any pressure drop in the intercooler. I've got a sticky over in the FI section on ls1tech about how to reference BOV's and WG's you may want to take a peek at. Its really old, but I believe I cover Tial.

[Rich Z]

Alot of people disable misfire detection on larger c.i. motors with cams and valvetrain to avoid falsely tripping misfire detections.

As for your wastegate referencing, how is it referenced? If you reference it to the compressor housings, you will lose boost due to any pressure drop in the intercooler. I've got a sticky over in the FI section on ls1tech about how to reference BOV's and WG's you may want to take a peek at. Its really old, but I believe I cover Tial.

But should ALL misfires be hidden? It looks to me that they are all disabled. Suppose there really are misfires taking place? Wouldn't I want to know about them?

The wastegates are now referenced to the back of the intake manifold. Single line that comes to a "T" and then branches to both wastegates. I can see benefits to both sides of this. On one hand I can see it would be nice to be referencing the actual boost as it exists where you want it to be, which is in the intake manifold. But on the other hand having the turbo's boost monitored and controlled AT the turbos just seems more elegant and logical to me. I specifically chose 14 lb springs because I presumed there will be a pressure loss at the engine, and that is to compensate for it. Plus with the single line coming from the intake manifold, there is only a single point of failure that could disable BOTH wastegates.

I'll look over that thread you mentioned. Thanks for letting me know about it. BTW, I have a thread over there trying to figure out exactly what turbos I have on my car. I feel it is prudent to make sure what I was told they are and are capable of is really factual.

[ACCLR8N]

I referenced my wastegate right before the throttle body. After the TB, when you let off, the 'gates will close and spike the pressure in the charge pipes. It might sound cooler coming out of your BOV but isn't doing anything else any good.

[Rich Z]

I referenced my wastegate right before the throttle body. After the TB, when you let off, the 'gates will close and spike the pressure in the charge pipes. It might sound cooler coming out of your BOV but isn't doing anything else any good.

Ah, yes. I've been trying to think of why hooking the wastegates up to the intake manifold could be bad for anything, and you provided the key to my understanding. The blow off valve is activated when there is a pressure differential between the the outside of the throttle body plate and the inside of that plate. However, with the wastegates referenced from the intake manifold, when the throttle body plate closes suddenly, such as between shifts, the wastegates will have a sharp transition between boost and vacuum that will slam the wastegate valves shut abruptly, and likely forcefully. When the wastegates are referenced to the outside of the throttle body plate, the control is merely between high boost and no boost, as the blow off valve relieves pressure.

I'm thinking that abrupt and forceful transition between full boost and full vacuum might be what Tial is talking about in relation to possibly damaging the wastegate.

I feel better now about my decision to change the wastegate plumbing. I wasn't really sure it was necessary as I couldn't come up with a scenario that seemed like it could hurt anything. Guess I just didn't think it through long enough.

Thanks.

[Rich Z]

Was able to take the car out today (actually Monday). Yesterday I put the opened fittings back onto the top plate of the wastegates so they would be open to atmosphere. I wanted to see if that would have any effect on that bothersome hiccup I've been getting while in boost. And long story short, I didn't have any problems this time out. Boost still tops out at around 150 kPa and then drops about 7 kPa before the trees whipping by so fast makes me nervous and I let off of the gas pedal.

So it looks like the hiccup MIGHT have been caused by my closing off that fitting. Still not 100 percent sure yet, because only one instance of a problem not showing up doesn't mean it isn't still lurking around waiting to pounce again. But I'm hopeful.....

Oh yeah, I copied the misfire tables from a stock Z06 into my tune, and I didn't get any yelping from the DIC about any misfires. I guess one of these days I need to set up a pid and dashfile to actually monitor for them.

I've uploaded the latest tune and log file if anyone is interested.

[joecar]

...

So it looks like the hiccup MIGHT have been caused by my closing off that fitting. Still not 100 percent sure yet, because only one instance of a problem not showing up doesn't mean it isn't still lurking around waiting to pounce again. But I'm hopeful.....

Oh yeah, I copied the misfire tables from a stock Z06 into my tune, and I didn't get any yelping from the DIC about any misfires. I guess one of these days I need to set up a pid and dashfile to actually monitor for them.

...Interesting.

Good deal :cheers:

[BLK02WS6]

Looks like it is coming around! You were rollin during that run for sure...

[Rich Z]

Looks like it is coming around! You were rollin during that run for sure...

Yeah, it still startles me when the turbos kick in. It's like a giant hand on the back of the car giving a huge push.

Well, I'm going to go ahead and start changing out the wastegates, and pulling the compressor housings off of the turbos to drill and tap the fitting holes I need. Weather forecast is calling for heavy rains over the next several days anyway.

[ACCLR8N]

You can't put a hose connection in your last intake pipe before the throttle body? That way you are still referencing pressure very near the manifold.

[Rich Z]

You can't put a hose connection in your last intake pipe before the throttle body? That way you are still referencing pressure very near the manifold.

Attaching the wastegates directly to the turbos just seems more efficient to me. I am using 14 lb springs, expecting there to be some loss to compensate for at the intake. These are rear mounted turbos so I would like to keep those boost lines controlling the wastegates local unless there is a real good reason not to. Besides, it's cluttered enough under the hood as it is. One reason I wanted rear mounted turbos was because I didn't want all that stuff crammed into the engine compartment. I've seen some people's engine compartments that looked like they would be absolute nightmares to do ANY work on the engine.

[Rich Z]

Sorry, been away for a while. Mostly because of rainy weather.

Anyway, got the new wastegates installed and did a couple of runs with them. Boost is now hitting 11.6 and 11.7 psi. Everything seems to be holding together OK, too. No couplers coming loose and the plastic airbridge didn't pop like I feared it might.

Found an EXCELLENT road to let it all hang out on yesterday. Virtually the middle of nowhere and nice and straight and flat. So I dropped it into fourth gear from a rolling idle and once the rpms were high enough where I didn't think it would bog, I opened it up to 100 percent until just over 6500 rpm. I didn't take it to redline because the slight curve in the road was coming up pretty darn quickly.

Log and latest tune are attached. I started pushing it into boost around frame 11920.

Car feels REALLY good lately. Throttle response is good, no errors showing up and the scans look OK to my untrained eye. Looks like car speed is pretty linear with engine rpm till I took my foot off of the accelerator pedal. Looks like a couple of rich spots in the AFR when I am in boost, though, but doesn't look too bad to me. Only thing I still have nagging me as some slight engine surging around 1200 rpm at 40 to 50 kpa while in higher gears. But that just might be the nature of the beast with this engine, perhaps. If it's something that I CAN fix, I would like to.

So can you guys take a look at this and see if I am overlooking something or just doing it the wrong way? I know there is more than one way to skin this kind of cat, but I just want to make certain I am not doing something just really dumb while learning this stuff.

Thanks.

[ACCLR8N]

Couple things I noticed: A0009 you have dropping off above 185 kPa. You should extrapolate that up by hand so you don't lean out if you over boost. If anything ramp it higher for protection.

There is a pretty steep step between 35 and 40 kPa, 800-2400 RPM in your B0101. My guess is that is your surging.

In your log it jumps up to peak nice and quick but then falls off. Turbo's might be a little small for racing, but good low end for the street.

[Rich Z]

Couple things I noticed: A0009 you have dropping off above 185 kPa. You should extrapolate that up by hand so you don't lean out if you over boost. If anything ramp it higher for protection.

There is a pretty steep step between 35 and 40 kPa, 800-2400 RPM in your B0101. My guess is that is your surging.

In your log it jumps up to peak nice and quick but then falls off. Turbo's might be a little small for racing, but good low end for the street.

Thanks.

I see what you mean by B0101. I smoothed out that range to make smoother transitions between cells, so I'll see if that helps. And I'll take a look at A0009 as well and increase the values up top too.

Yeah, I was more interested in low end responsiveness than top end power with the turbos. When I did that run I logged, I was at 105 kPa at just over 1750 rpm. So I'm happy with that.

Thanks for your help.

BTW, I did a little video of that run I did. -> http://www.youtube.com/watch?v=LUhun5zl1e8

[Rich Z]

Well, didn't help much when I smoothed out B0101. Been trying a bunch of stuff. Actually lost track of what exactly as I was just pulling over and making changes, so I didn't jot down any notes. I thought perhaps the values were wrong on B4349 indicating the change made from the 75mm to 90mm throttle body. I had 0.0330 there and changed it to 0.0157. Car didn't want to idle at all if I did anything to the gas pedal. And even just sitting at idle, I watched the AFR gradually creeping up into the lean zone. Played around with B4403 too, with no positive results.

Wound up disabling LTFTs as that seemed to be causing some surging on me. Still had some, so I disabled STFTs as well, but that didn't change anything.

One thing I noticed was that if the engine stalled on me, I had a devil of a time getting it started again. Seems like I had to let it set for a period of time before it would want to start right up, so I changed the relevant settings (I think) at B3201 and B3203. Haven't stalled it since then so I don't know if that helped or not. But I do know I still have that annoying surging at low speeds. Seems to be low RPM and light load on the engine where it is most noticeable. Which is often just barely over idle driving at under 10 mph, or in any gear that is at the lower limit of the RPM range in that gear.

The answer is in there somewhere, but I just can't figure out where yet....