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Thread: Sanity check, please...

  1. #1
    Lifetime Member Rich Z's Avatar
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    Default Sanity check, please...

    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.
    1. 2002 Corvette Z06
    2. custom 427 built by LME (9.8:1 CR)
    3. STS rear mounted twin turbos
    4. 90mm LS9 throttle body
    5. FAST 102mm intake
    6. LGM long tube headers
    7. Mild turbo cam (232 228/116/.630 .630/109.25)
    8. MAP referenced fuel pressure regulator
    9. Reworked fuel system with dual intank fuel pumps
    10. Fuel injectors from FIC (72 lb/hr)
    11. 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.....
    Attached Files Attached Files

    CorvetteFlorida.com

    2002 Corvette Z06
    427 RHS block built by LME
    STS rear mounted twin turbos
    It nearly died on the operating table, but I'm bringing her back.

  2. #2
    Lifetime Member BLK02WS6's Avatar
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    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...
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


  3. #3
    Lifetime Member Rich Z's Avatar
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    Quote Originally Posted by BLK02WS6 View Post
    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?

    Quote Originally Posted by BLK02WS6 View Post
    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:



    Quote Originally Posted by BLK02WS6 View Post
    -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.

    Quote Originally Posted by BLK02WS6 View Post
    -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....
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    CorvetteFlorida.com

    2002 Corvette Z06
    427 RHS block built by LME
    STS rear mounted twin turbos
    It nearly died on the operating table, but I'm bringing her back.

  4. #4
    Lifetime Member BLK02WS6's Avatar
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    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...
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


  5. #5
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    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.

  6. #6
    Lifetime Member BLK02WS6's Avatar
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    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:


    And, here is one of many places it is lean rolling into the throttle:


    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?
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


  7. #7
    Lifetime Member BLK02WS6's Avatar
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    Here you can see that you don't have any timing pulled until 185 kpa using the boost timing table:



    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.
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


  8. #8
    Lifetime Member Rich Z's Avatar
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    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.

    CorvetteFlorida.com

    2002 Corvette Z06
    427 RHS block built by LME
    STS rear mounted twin turbos
    It nearly died on the operating table, but I'm bringing her back.

  9. #9
    Lifetime Member BLK02WS6's Avatar
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    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?
    GM EFI Tuner
    02 WS6 9.41 @ 143 MPH 3675#, drag radials, pump gas, through the mufflers - sold


  10. #10
    Lifetime Member Rich Z's Avatar
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    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.

    CorvetteFlorida.com

    2002 Corvette Z06
    427 RHS block built by LME
    STS rear mounted twin turbos
    It nearly died on the operating table, but I'm bringing her back.

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