Help with vehicle staying running and cold starts without throttle aid...

[sac811]

I cannot for the life of me, get my vehicle's tune correct so that it will start on it own without giving it gas on cold starts. It will start without help once warmed up though.

And also after a complete cold start the vehicle will not stay running after gear changes. Idles fine in park at first, then put it into reverse...after about a second it starts dropping rpms then stall saves, then dies. Restart, same thing happens again until I can give it enough gas to stay going for a while. But if it isn't warmed up enough before the next complete stop it will die again.

Then if it isn't completely warmed up but not completely cold its a 50/50 shot that it acts this way.

I've been through all the normal idle threads and tutorials and just can't get these 2 situations tuned out.

I have the right desired air flow, IAC counts, etc.

I am posting my tune below, and help would be GREATLY appreciated.

Thanks

Jeremy

Current Tune:
16668

[bimbleuk]

You probably won't wan't to hear this but the usual procedure is to get your VE & MAF dialled in fairly accurately before you get your idle and low speed driveability right. Looking at your VE table and MAF cure they are just not looking very clever currently. I believe they may need a lot more work to smooth them out before you can cure your idle.

If they aren't correct then you may be chasing your tail trying to cure the other issues. Not very helpful but I tend to look at the VE and MAF tables in any tune to see what your working with.

[joecar]

+1 VE and MAF both need work.

Post log files showing RAFIG pids.

[sac811]

Well im not sure what else I can do for ve and maf, ive done calc.maft plenty of times. I guess I can swap to calc. Vet and do that a bunch of times. But I keep getting the same stuff thats already in my ve and maf tables.

[statesman]

You've had this problem since last year. I saw your previous thread on this...

http://forum.efilive.com/showthread.php?23395-Attempting-to-get-tune-correct-so-no-gas-pedal-is-needed-on-cold-starts

I've had a look at your tune, and a lot of the tables don't look quite right to me. Do you have a stock tune to start over with?

[sac811]

Ive since added more mods and done calc.maf after it because of a new maf sensor and intake manifold/tb and have since modified other tables to try and help with initial startup since then with no luck.

[bimbleuk]

Is it worth posting a pic of your inlet setup as it looks like something is causing disruption to the air through the MAF. Do you still have a diffuser before the MAF? You have a ported TB? Not always a good idea that can change the airflow over the IACV port for example and affect the stock tables. The injector table suggests your FPR is vacuum referenced? Just trying to check some basic stuff that affects a lot of the main reference tables.

It's frustrating as I have a very similar setup 224/226 112 cam with a tadge less lift, mine is manual though. I used the LS1-M6 base tune from one of the tutorials and that's served me well. Only slightly tweaking the throttle cracker/follower tables to suit my Edelbrock 80mm TB.

[statesman]

Okay. I think you're better off starting over with a stock tune, but if you want to keep using your current tune then try this...
Set all values in B4105 to 450.
Set all values above zero IAT in B4205 to 35
Set B4206 to Disable.
Add 0.3 to all values in B3701.
Make sure B4001 is correct for your current injector size.
then
Retune your MAF and VE tables.
then
Redo RAFIG/RAFPN

If you find it running too rich or too lean on cold start, then adjust B3632

And, as warlock007 already pointed out to you in your previous thread, with your cam you should idle a bit higher... especially important for cold starts.

[joecar]

VE:
after you redo your VE, you must get rid of any sharp steps/drops/spikes/holes...
large steps/drops/spikes/holes cannot physically exist, so you have to flatten/interpolate these:
i.e. the un-hit cells have to be brought up or down so that they are close to the hit cells
--> I'm talking about only minimal smoothing
ripples of a few percent in one direction are ok) (i.e. not major steps)

MAF:
after you redo your MAF, same thing, you have to bring the un-hit cells into the 4th order polynomial curve;
there is a spreadsheet somewhere on the web to do this, but it can easily be done by hand too;
i.e. the MAF curve must look like a smooth 4 order polynomial (i.e. its slope keeps increasing);
the MAF curve has to be quite smooth (this is how the MAF works), but don't use the smoothing tools, do it by hand.

[sac811]

I have a Lingenfelter 100mm mass air flow sensor slot style so no it does not have a diffuser any longer I have a 92 millimeter fast throttle body drive by cable and a TrailBlazer SS intake radically ported for the sake manifold

also the IAT sensor reads off on this computer because I cannot adjust the i-80 scalar so I unweighted the IAT sensor because of this

[statesman]

Okay then, do the rest... just ignore changing B4205.

Put your MAF table back to the Lingenfelter specified curve before retuning your MAF table.

[bimbleuk]

OK I was trying to decipher your tune file name!

With the slot style MAF they can be sensitive to placement to around the circumference of the tubing if there's any disruption to air flow immediately upstream i.e. sharp bends. Not always so easy to relocate of course.

[sac811]

Using the same information as I had in the previous file but with smoothing the VE and MAF tables here is my 11th OL iteration file:
16679

Here is the Ling. MAF info for the curve, which is almost the same except I have more airflow until u get very high in frequency:
16678

My Calc.MAFT shows almost exact same data every time for VE table and MAF curve, other than the fact that the weather keeps changing from 40 to 80 every other day here in Louisiana.

Also my desired idle speeds are in b4603 and are up to 900 rpms when it is cool, settling to 725 at 80C...so it doesn't seem like idle speed should be the issue on cold starts. Unless they need to be 1200 or something...

Also here is a partial RAFPN warm up log:

16681

[statesman]

Can you do a cold start log, and log the following;

SAE.TP
SAE.MAF
SAE.RPM
SAE.ECT
SAE.MAP
SAE.SPARKADV
GM.AFR
GM.IAC
GM.KR
GM.IBPW1

Start logging before before you start the engine. Do a start without any throttle aid and then a start with throttle aid. Then do a small cold engine drive and log a stall and restart (if you still have the stalling issue).

[sac811]

Here are a couple cold start attempts with and without throttle aid, with stalling after starting going from Park to Reverse to Drive, etc.:

16700

16699

Current Tune running, while the above logs took place:

16698

Also take notice that I increased all idle speeds by 75 rpms and have since retuned for that but am having the same problems anyway.

[statesman]

Okay, I've looked at your logs and it looks like your engine is bogging down when cold (too much fuel). I've modified your tune a bit. Flash in this tune and do another cold start log the same way as you did the last one... and logging the same pids.

[sac811]

Okay, I've looked at your logs and it looks like your engine is bogging down when cold (too much fuel). I've modified your tune a bit. Flash in this tune and do another cold start log the same way as you did the last one... and logging the same pids.

Here are 2 sets of cold start logs after loading in your modified tune:

16706

16707

Other than not starting without throttle aid, do you have any ideas on how to fix the surging and dying that are shown in these logs as well, once started?

[statesman]

Okay, I've looked at your logs and I noticed something that I missed last time. Your problem is not enough air when cold. Your IAC is maxing out. I'm guessing that you haven't drilled or cracked your TB yet. You've got an IAC count around 125 hot... should be 30-50. You need to get your IAC counts down. We'll probably have to put a bit of the fuel back into your cold running, but you need to fix your air first.

[sac811]

Okay, I've looked at your logs and I noticed something that I missed last time. Your problem is not enough air when cold. Your IAC is maxing out. I'm guessing that you haven't drilled or cracked your TB yet. You've got an IAC count around 125 hot... should be 30-50. You need to get your IAC counts down. We'll probably have to put a bit of the fuel back into your cold running, but you need to fix your air first.

When its hot the iac counts are right at 40, it doesnt get to that until ive been riding around for 20-30 mins tho.

The default IAC is set to 310, should that be changed maybe before opening up the tb blade some and ending up with higher iac counts once actually warm?

For Example:

16709

[ACCLR8N]

I'm switching to an LS7 card style MAF myself on an E40 ECM. What I have learned as you mentioned the IAT output is not compatible and needs to be re-scaled. Since this table is not available I'm switching to a separate IAT that is compatible. Isn't a lot of the cold start fueling based on coolant and intake air temps?

[statesman]

Isn't a lot of the cold start fueling based on coolant and intake air temps?

He has his after-start IAT enrichment zero'd out, but it will still have a serious impact on his temperature blending... which determines fueling. It would probably be a good idea if sac811 switched to a separate IAT, which is compatible, like you are doing.

[statesman]

When its hot the iac counts are right at 40, it doesnt get to that until ive been riding around for 20-30 mins tho.

The default IAC is set to 310, should that be changed maybe before opening up the tb blade some and ending up with higher iac counts once actually warm?


No, leave your default IAC. I've modified your IAC table. See if this helps.

[sac811]

No, leave your default IAC. I've modified your IAC table. See if this helps.

This is the start with your new file before performing rafig rafpn:

16711

I will have a start attempt with same file after rafig later today.

[sac811]

Here is my cold start log after rafig/rafpn:

16713

It seemed like it may have wanted to start better, but it definitely ran better than in the past with less surging and dying.

[statesman]

It seemed like it may have wanted to start better, but it definitely ran better than in the past with less surging and dying.

We're making progress... that's a good thing.

Can you post your new tune with your updated airflow.

[sac811]

We're making progress... that's a good thing.

Can you post your new tune with your updated airflow.

Newest tune file:

16716

[joecar]

By what method are you correcting VE and MAF tables...?

[sac811]

By what method are you correcting VE and MAF tables...?

Calc.maft

[statesman]

Your desired airflow table looks better now.

Okay, here's Mod3. Only small changes, but should reduce the surging.

Post a log when you've tried it.

[statesman]

By what method are you correcting VE and MAF tables...?

Does something look wrong to you?

[sac811]

Your desired airflow table looks better now.

Okay, here's Mod3. Only small changes, but should reduce the surging.

Post a log when you've tried it.

So im just doing another start up log like ive been doing correct?

[statesman]

Yes, same as you've been doing, same start up log... same pids. I altered your startup spark as well, so I want to see if it's more inclined to start now.

[joecar]

Calc.maft


Does something look wrong to you?I'm sanity checking on the procedure...

sac811,

are you using wideband only (I see trims/CL disabled in the log)...?
if so, what pid are you using to correct the VE table (CALC.WO2BEN)...?

Just sanity checking

( if you use CALC.SELBEN, this will have flat 1.00 spots from LTFT's being zero due to trims/CL being disabled, and this will mislead your efforts )

[joecar]

stateman has you on the right track :cheers:

[sac811]

I'm sanity checking on the procedure...

sac811,

are you using wideband only (I see trims/CL disabled in the log)...?
if so, what pid are you using to correct the VE table (CALC.WO2BEN)...?

Just sanity checking.

Yes wideband only and calc.wo2ben

[joecar]

Yes wideband only and calc.wo2benOk, cool... carry on with statesman's instructions.

[sac811]

3 cold start attempts this morning (they didn't want to act right as the same file for some reason):

16722
16723
16724

The last is it running for a bit after throttle aid start.

[sac811]

This is a successful start without throttle aid at 40C and the ride home afterwards:

16725

Mind you, the cold starts in the previous thread were without proper rafig/rafpn for that cold of a start, since the temperature just went from 80 degrees F yesterday to 40 degrees F this morning...hate these weather changes up and down in Louisiana.

[statesman]

Unaided start at 40C is good. You will need to redo your RAFIG/RAFPN for those colder temperatures.

Okay, here's Mod4. A few changes in this one. I think you'll see a good improvement with these changes.

[statesman]

I'm sanity checking on the procedure...

Always good to have an extra set of eyes doing some sanity checking. :cheers:

[sac811]

This is my most recent cold start attempt:

16734

I should have plenty of time this weekend to retune b4307, VE and MAF tables this weekend also after you have had a chance to get me the most up to date tune you were talking about where fueling would be adjusted.

Thank you

Jeremy

[sac811]

Rafig/rafpn adjusted cold start attempt:

16737

[statesman]

I've compared your MAF table to the manufacturer's specified table and I'm getting a weird graph. Two questions... did you filter transients when doing your MAF?... and are you using the stock fuel pump?

I'll have a look at your latest logs and work out a new tune for you now.

[sac811]

I've compared your MAF table to the manufacturer's specified table and I'm getting a weird graph. Two questions... did you filter transients when doing your MAF?... and are you using the stock fuel pump?

I'll have a look at your latest logs and work out a new tune for you now.

I filtered out transients where tps moves more than 1% per 100ms out. Less than 172 degrees ect out, etc.

No it is not a stock fuel pump, it is a walbro 255, with 44lb/hr marine injectors, and a vacuum referenced fuel pressure regulator.

I am not sure why my maf readings would be the same as a base maf table tho. I expected it to flow different amounts at different frequences than the base table, as figured all different setups would vary. But I could definitely be wrong.

[statesman]

Yes, it will be a little bit different to the manufacturer's table... like you said, different setups affect the airflow but it should be a fairly smooth difference where yours seems to be in waves. I'm no expert in turbulence, so maybe it's alright.

I'll put up a new tune for you in a few minutes.

[statesman]

Okay, here's Mod5. Some changes to try to fix your cold start and a couple of changes to your fueling. It will send you a bit rich, so do your MAF and VE before doing your RAFIG/RAFPN.

[sac811]

Here are 3 logs with unthrottle aided start attempts-

Just VE, MAF, and Rafig:
16758

Same tune, with 25% less b4343:
16759

Same tune, with another 25% less b4343
16760

Still no luck starting cold

In post after this I will upload latest tune

[sac811]

Most recent tune:

16761

Everything is running much better other than cold start, sometimes having a stall and sometimes having issues holding idle without surging up and down if the temperature deviates much from 80 degrees F that the VE, MAF, and RAFIG where tuned under though.

Hopefully once I revert to closed loop it will help with adjustments for different temperatures though.

[statesman]

Closed loop will only help with rich or lean conditions, which should mostly have been addressed by having tuned your MAF and VE.

Okay, here's Mod6. I've added fuel to your startup. Do a cold start log and then continue logging so I can see your stalls and surging as well.

[sac811]

Closed loop will only help with rich or lean conditions, which should mostly have been addressed by having tuned your MAF and VE.

Okay, here's Mod6. I've added fuel to your startup. Do a cold start log and then continue logging so I can see your stalls and surging as well.

I figured once I have the MAF activated again it would adjust some other things based on airflow it sees too though, otherwise no vehicle would ever run right if the temperature changed drastically because that changes airflow dramatically. Or at least every time I rafig in different temperatures it does.

[sac811]

I have 2 logs for you to look at the first has cold start unaided and aided along with lots of driving, surging, key cycles, etc. The second has some surging and a stall at the end.

First:
16765
Second:
16766

[statesman]

Okay, I went agressive on your starting fuel... and it hasn't helped at all. Go back to your previous tune "OR50lessMod5".

What I'm seeing in your logs is that your IAC is still maxing out on cold starts, and it shouldn't. I think you might need to crack your TB a bit more... get your hot engine IAC counts down to about 20.

Your surging appears to be caused by your engine going lean. Your AFR moves around a lot and I'm starting to think that you're getting cam reversion, causing your MAF to mis-read the airflow. When you've got some time on your hands try failing your MAF, redo the idle area of your VE (preferrably using the narrowbands) and then run the engine in OLSD, see if this fixes the surging issue.

[sac811]

Here is a log of an actual non-throttle aided start finally:

16788

Here are 2 logs running around with some surging and stalling:

16789
16790

These were all on this tune:

16791

I do believe most of the surging happened when I did rafig/rafpn after the 512 log and applied it to the tune. But the tune wasn't ready for that much air at operating temperature after FULL warm up.

[sac811]

So I did rafig/rafpn again when I got home this afternoon and adjusted b4307 again for this new tune:

16792

I haven't gotten the chance to actually try it out to see if it has the same almost stall/surging at idle yet, but can check tomorrow.

[statesman]

Here is a log of an actual non-throttle aided start finally:

From what I can see in your log, that is a really good cold start. It looks like your cold start issue is fixed.

Do a bit of logging on your fresh tune and we'll try to get the surging fixed now.

[statesman]

So I did rafig/rafpn again when I got home this afternoon and adjusted b4307 again for this new tune:

I haven't gotten the chance to actually try it out to see if it has the same almost stall/surging at idle yet, but can check tomorrow.

Your desired airflow looks really low at 80C now. I think maybe something has gone wrong with your rafig/rafpn. If it wont idle at 80C, then bump up your desired airflow for that temperature.

[sac811]

Here are 2 logs with my newest tune:

16798
16799

This tune where I only changed desired airflow based on rafig/rafpn made it to where it did not cold start like it was before.

Has some surging and some issues running here and there.

Here is tune:

16797

[statesman]

Okay, something doesn't seem to be going right with your rafig/rafpn process. I see you've switched to closed loop... so I can't really compare those logs to the previous ones. Your cold start seems to be just on the limit of your IAC... and this was a colder start than before, so crack your TB blade just a little bit more and get your hot engine IAC counts down to 15.

I've made a few changes to your tune. I've put your IAC table back to stock so your airflow numbers line up better now that we're coming off the IAC limit. There's a few other changes including reducing your stoich value a bit... I think your fuel might have a bit more ethanol than you had allowed for.

Okay, here's Mod 7. Try running this tune without doing a rafig/rafpn first, just redo your VE and then make a log. Then let the engine cool off overnight and do a rafig/rafpn on a stone cold engine and log that as well. Then crack the TB blade a bit after you've done your rafig/rafpn. It will only alter your airflow a bit but you might want to redo your rafig again later.

[sac811]

Ok, running this tune:

16809

Here are 2 logs of the PIDs you have been having me log:

16810
16811

Tomorrow I will do a cold rafig log. Did you want me to do that log then just apply the corrections like normal, adjust tune and log that tune?

I have not touched the tb set screw yet either btw.

[statesman]

Yes, do that. I'll have a look at your logs now.

[statesman]

Your surge looks like you're going lean at idle. Your VE table goes low around the idle area. You'll have to redo the idle area of your VE table using your narrowbands.

After you do your cold rafig, do your idle VE with NB's. Don't worry too much about cracking your TB blade for now.

[sac811]

Here is my current closed loop tune to log NBO2s for IDLE VE:

16818

Here are some logs of me running around with above tune:

1. This one will have the most total hits at idle etc. - 16819

2. This is just a quick drive from my house to another location, so may not be worth it compared to the above one - 16820

Looking for help using these logs to adjust my VE table at idle or perhaps even 1600 rpms and less at low kpa map points.

Thank you

[statesman]

Your idle trims weren't as bad as I thought they would be. Your latest logs show a good idle now for brief periods, but then your IAC counts rise dramatically for no apparent reason which kicks off your surging. You'll have to log some IAC PID's to see what's causing this.

Log these PID's;
SAE.TP
SAE.MAF
SAE.MAP
SAE.RPM
SAE.VSS
GM.IAC
GM.IAC_SUM_DMA
GM.IAC_LTD_DMA
GM.IAC_STD_DMA
GM.IAC_WD_DMA
GM.IAC_FAN_DMA
GM.IAC_OT_DMA
GM.IAC_PARK_DMA
GM.IAC_TC_DMA
GM.IAC_TF_DMA

I didn't count how many channels that will use... but don't worry if it goes over 24. There should still be enough resolution to see what's jumping up. Log these PID's closed loop speed density... same set up as for your last logs. Log with engine at full operating temperature.

Okay, here's Mod8. Only small adjustments needed to your VE table.

[sac811]

Ok, here is a log of the PIDs you listed above from driving around today. Some of it is not at full operating temp, but I included ect so you can filter those out.

16831

[statesman]

Okay, here's Mod9. A few changes to your air corrections. Log the same pids as last time, including ect.

[sac811]

Okay, here's Mod9. A few changes to your air corrections. Log the same pids as last time, including ect.

Ok, here is a log from you Mod9 tune:

16836

[statesman]

I've been looking at your logs and what I've found is that your Short Term Idle Trims are moving too much... they are not obeying their limits. Also, your Throttle Cracker is randomly adding air when it's not supposed to. I've had a brief discussion with joecar about this and we're both thinking the same thing, which is... to fix this, you might have to do a full flash with a known good file... and apply your calibration to that file.

[sac811]

I've been looking at your logs and what I've found is that your Short Term Idle Trims are moving too much... they are not obeying their limits. Also, your Throttle Cracker is randomly adding air when it's not supposed to. I've had a brief discussion with joecar about this and we're both thinking the same thing, which is... to fix this, you might have to do a full flash with a known good file... and apply your calibration to that file.

Thats no problem, just upload the good file you want me to use, and then I can full flash, and then cal flash my tune to it after.

Thank you

Jeremy

[statesman]

Which transmission have you got?

[sac811]

Which transmission have you got?

Built 4l60e with vacuum modulated valve body.

[statesman]

Okay. I pulled this file from holdencrazy... which is a repository for stock tunes. It's the same OS and calibration as yours. It should be a good tune file.

[sac811]

Okay. I pulled this file from holdencrazy... which is a repository for stock tunes. It's the same OS and calibration as yours. It should be a good tune file.

When I go to copy this to my flashscan V2 it says it is not supported by bbx flashing etc.

I don't have a laptop. How do I make this file usable, by the V2 handheld?

Edit: Nevermind I think I got it. Opened it in Tune program and saved as a ctz file instead of tun.

This should work correct?

[joecar]

From V7 tunetool, open the .tun file and save it as .ctz.

From V8 S&T, there's a tool to convert the .tun to .ctz.

[sac811]

Okay. I pulled this file from holdencrazy... which is a repository for stock tunes. It's the same OS and calibration as yours. It should be a good tune file.

I did the Full flash with this file, then the cal flash with the most recent Mod9 file posted, then the TPS reset.

And here is the log afterwards:

16843

Not the results we were looking for at all. In fact went in the opposite direction on drive-ability.

[statesman]

Okay, I've looked at your log and it did fix the problem of your TC randomly adding air. Now we'll have a better chance of tuning out your surge. Do a log with the original pids you were logging... with the pids I listed in post #14... and log LTFT's instead of WB since you're in CL now.

Also, read the tune back out of your PCM... save it as "GoodOS" and post it up with your next log.

[sac811]

Okay, I've looked at your log and it did fix the problem of your TC randomly adding air. Now we'll have a better chance of tuning out your surge. Do a log with the original pids you were logging... with the pids I listed in post #14... and log LTFT's instead of WB since you're in CL now.

Also, read the tune back out of your PCM... save it as "GoodOS" and post it up with your next log.

Ok here is the GoodOS file:

16847

I should be able to go back to the previous way of logging and get you some info later today.

[sac811]

I opened my throttle blade a little more because it was still not wanting to start on dead cold starts sometimes, then logged RAFIG, applied that rafig then with that slightly modified tune I made this log:

16848

Rafig tune on TB set screw adjustment:

16849

[statesman]

Your cold starts are always going to be problematic until you widen the IAC air passage in that TB.

Okay, here's Mod9.1. I called it 9.1 because it's only minor adjustments to Mod9. Small adjustments can do big things... sometimes.

This is just a spark adjustment to help focus your idle to the target speed.

Let me know how it goes.

[67SS509]

Been following this and want to make a few comments based on my experiences.
The size cam you are running should not be causing as much problem you are having. One thing I would do is cut the Base Spark back to about 19-20 degrees. Always include spark in your PID's. Your Idle Air numbers are just not big enough for a cam.....do you have a vacuum leak? Would explain all the surging. For better cranking add air in the Startup Friction Air table and then decay it faster. Crack your throttle screw to obtain near 0 IAC counts until you get the surging resolved and then set it to obtain 30-40 IAC counts under normal conditions.

[sac811]

Here is a log from today of your mod9.1 tune, but the wife was in the vehicle so had the a/c running most of the time:

16861

At the last couple minutes of the log is without a/c running for sure though if it makes a difference

[sac811]

Been following this and want to make a few comments based on my experiences.
The size cam you are running should not be causing as much problem you are having. One thing I would do is cut the Base Spark back to about 19-20 degrees. Always include spark in your PID's. Your Idle Air numbers are just not big enough for a cam.....do you have a vacuum leak? Would explain all the surging. For better cranking add air in the Startup Friction Air table and then decay it faster. Crack your throttle screw to obtain near 0 IAC counts until you get the surging resolved and then set it to obtain 30-40 IAC counts under normal conditions.

Get what your saying, but pretty much everything you have recommended has been tried. None of it helped unfortunately. Slowly but steadily statesman has gotten me a much better running tune than when I started though. So at least we are getting there, thanks for the help.

[statesman]

Been following this and want to make a few comments based on my experiences.
The size cam you are running should not be causing as much problem you are having. One thing I would do is cut the Base Spark back to about 19-20 degrees. Always include spark in your PID's. Your Idle Air numbers are just not big enough for a cam.....do you have a vacuum leak? Would explain all the surging. For better cranking add air in the Startup Friction Air table and then decay it faster. Crack your throttle screw to obtain near 0 IAC counts until you get the surging resolved and then set it to obtain 30-40 IAC counts under normal conditions.

Hi 67SS509, and thanks for your suggestions. The problem with the cold starts is that the IAC air passage on this aftermarket TB is a bit restricted and he is already maxing out his IAC counts on cold starts so commanding more air in any of the tables isn't going to help because this TB just can't physically deliver any more idle air. The spark looks a bit high for idle, but it was at 35 degrees before and I have brought it down a bit.. and now it seems to be where the engine wants it to be. Keep following our progress... and any more suggestions are always welcome.

[statesman]

Here is a log from today of your mod9.1 tune, but the wife was in the vehicle so had the a/c running most of the time:

At the last couple minutes of the log is without a/c running for sure though if it makes a difference

I've made some adjustments to your a/c air compensation. These adjustments work well on my engine so they should work for yours too. If you don't like the smaller air compensation, you can always put those tables back to what they were.

Okay, here's Mod10. Your small pulse table looked too flat in the area where you surge, so I've made adjustments to it. Without injector data, it really is a guess... but I think this adjustment might help with your idle. You'll have to redo your VE yet again.

Post a non-a/c log after you redo your VE... but also let me know if the a/c adjustments I've made work for your engine or not.

[sac811]

After redoing the VE table here is my most up to date tune:

16893

And then here is a log of this tune from today:

16894

Sometimes it seems fine, then other times it wants to surge and/or die. But it seems to get worse, the longer the vehicle runs...maybe thats just in my head though.

[statesman]

Your log is showing random spikes in airflow. I think this is some kind of physical intermittent fault, not a tuning issue.

Okay, here's Mod11. This will try to fix the surge/stall when you come off the throttle at low speeds. Log the same pids as last time.

[sac811]

Your log is showing random spikes in airflow. I think this is some kind of physical intermittent fault, not a tuning issue.

Okay, here's Mod11. This will try to fix the surge/stall when you come off the throttle at low speeds. Log the same pids as last time.

I did a full flash with you most recent tune to see if that made a difference with the random spikes, along with unplugging and plugging back in the IAC sensor.

But here is the log:

16900

[statesman]

I've looked at your latest log and noticed that you have a large variation in IAC counts for what is essentially the same amount of airflow at the same operating temperature... and I can't work out why.

Frame 1300 has you at 94 IAC counts for 8.28g/s airflow at 81C ECT.
Frame 9600 has you at 63 IAC counts for 8.11g/s at 80C ECT.
Frame 35660 has you at 32 IAC counts for 8.68g/s at 81C ECT.

In all 3 frames, you're at stable idle with similar injector pulse widths... which would indicate that airflow is indeed similar. I would think that there's a problem with either your IAC valve or with your PCM.

If anyone reading this has seen this kind of thing before or has any suggestions... then please leave a comment.

[sac811]

Just an update, I have purchased a new IAC valve and PCM, but have yet to install it.

When I do, Hopefully that will solve the problem. But am waiting on the PCM to be delivered, and then I will need a little spare time, because while I install the new IAC valve I plan on opening up the IAC passage so it is no longer maxing out.

Thanks

[sac811]

Since my last update, I have installed a new IAC sensor, new PCM, opened up the IAC port on the FAST 92mm tb, and worked on an potential ground wire problems.

Here is my current tune:

17178

Here are 2 logs using the previous datalog pids:

17179

I believe the tune is running pretty well without the A/c on, but with the A/c on it is very up and down and wanting to die occasionally. I have a log of this, but the file is bigger than the 2.0mb limit on file size, so I will just log it again tomorrow.

[statesman]

It looks like the adjustments I made to your A/C airflow correction hasn't worked well for your setup so I'm changing it back and also adding a bit of idle air.

See how you go with this.

[sac811]

Here is a log from today using your most recently updated tune for me, but with the A/c running:

17185

[statesman]

Okay, just a few changes here. Do a log with your A/C running with this new tune.

[sac811]

Here is the new log with A/c running:

17190

I'm not sure completely, but I dont think it liked the increased timing added around idle rpms. I had lowered those previously to what they were based on logs showing that the vehicle seemed to do better at those timing levels. But take a look at the log and see what you think. I'm definitely not as good with finding out what works right compared to you of course. Not sure if the VE changes helped or hurt, since the timing was also changed.

One more thing I noticed was that when running with the A/c off, it seemed to run worse than before with these changes. Again my guess is the timing, but I don't know how much the VE effected it either way though.

[statesman]

I can't feel or hear your engine so your feedback helps. I've gone back to the previous tune and made a couple of air adjustments. With this new tune, I'd like you to log a different set of PID's.

SAE.TP
SAE.MAF
SAE.MAP
SAE.RPM
SAE.ECT
SAE.VSS
GM.IAC
GM.IAC_TC_DMA
GM.IAC_TF_DMA
GM.IAC_LTDAC_DMA
GM.IAC_LTPNAC_DMA
GM.IAC_STDAC_DMA
GM.IAC_STPNAC_DMA

Do your log with the A/C on, but also let me know if driving with the A/C off has suffered at all with the throttle cracker change I made.

[sac811]

Here is my current tune:

17201

In the tunes a bit early in thread I had the low octane spark tables 6 degrees less than the high, but forgot with MAF failed it defaulted to low. So copied those over to low and then did these logs with air on and new pids you have in last post:

17199
17200

[sac811]

Another couple logs with same tune as above:

17212
17213

[statesman]

Your air looks alright. I've made a few changes and unfortunately you'll need you to redo your RAFIG/RAFPN and your VE with this new tune. When you've done that, I'd like you to do a log with the pids you were logging before... the one with the long term and short term trims.

[sac811]

Here is latest tune used to get logs below:

17223

And here are drive and park logs with MAF readings after an hour or so of driving then being back home taking these logs at idle:

17225
17224

And if you have time, adjust the low octane timing table to the timing you said works the best for idle control.

Thank you

[statesman]

The low octane timing table isn't referenced during idle conditions.

Here's a new tune with a slightly lower base spark... Do a RAFIG/RAFPN with this new tune and then do a driving log in closed loop with the A/C on... logging with the old pid list, which has the short and long term fuel trims.

[joecar]

+1 what statesman said, HO/LO timing tables are not referenced during idle.

[sac811]

The low octane timing table isn't referenced during idle conditions.

Here's a new tune with a slightly lower base spark... Do a RAFIG/RAFPN with this new tune and then do a driving log in closed loop with the A/C on... logging with the old pid list, which has the short and long term fuel trims.

Here is my newest update to tune with rafig/rafpn done, etc:

17233

And logs for rafig/rafpn at full operating temperature after an hour or so:

Park
17234
Drive
17235

Basically a difference of 7.5 g/s according to rafig and maf showing 10.43 g/s
and 7 g/s according to rafpn and maf showing 9.5 g/s

So a good bit off.

[statesman]

Okay, the slope of your IAC effective area table isn't right for your new throttle body... that's why the amount of error is different between park and drive. We can't just 'shift' the table like most people do... we're going to have to re-calibrate that table to suit the airflow characteristics of your IAC passage. This new tune has a slightly different IAC table slope. It's just a starting point, and we'll make adjustments from there. I'll need logs from your entire rafig/rafpn process... cold to hot. Make sure you include IAC counts in the logs.

[sac811]

I could be reading things wrong, but I think you nailed it on the first try.

Here is my most recent tune with rafig/rafpn done from cold and then hot:

17246

And here are the log files that got me there from your last tune:

17249
17248
17247
17250

Other than having the colder desired airflows since its summer and all of course.

Looks like the average MAF reading and desired airflow from rafig/rafpn are almost exact.

[statesman]

Yeah, it's fairly close when hot but doesn't line up all that well when cold. Here's an adjustment that should get it to line up a bit better. Redo your rafig/rafpn and post the logs again.

[sac811]

Logs:

17260
17261
17259
17258

Updated Tune:

17262

[statesman]

Did you redo your MAF and VE before or after you did the rafig/rafpn?

[sac811]

Did you redo your MAF and VE before or after you did the rafig/rafpn?

Did rafig before ve/maf change.

[statesman]

Okay, it appears that rafig is underestimating your engine's air needs... this sometimes happens with cammed engines but I don't know why. With this new tune don't do any rafig or ve adjustments... just flash and drive. I'd like you to do a log with the a/c on... and log these pids;

SAE.TP
SAE.VSS
SAE.ECT
SAE.IAT
SAE.MAP
SAE.MAF
SAE.SPARKADV
GM.IAC
GM.IACDES_B
GM.IBPW1

[sac811]

Okay, it appears that rafig is underestimating your engine's air needs... this sometimes happens with cammed engines but I don't know why. With this new tune don't do any rafig or ve adjustments... just flash and drive. I'd like you to do a log with the a/c on... and log these pids;

SAE.TP
SAE.VSS
SAE.ECT
SAE.IAT
SAE.MAP
SAE.MAF
SAE.SPARKADV
GM.IAC
GM.IACDES_B
GM.IBPW1

Here is the log you asked for:

17281

[statesman]

Okay, I'm going to lean out your idle a bit and a couple of small adjustments to your air. I'd like you to log the same pids as your last log.

[sac811]

A few logs I did with the latest tune:

17296
17297
17298

[statesman]

Check your PMs