Gatsby

iTrader: (7)

Hey all,

I searched for a half hour and I'm sure this question has come up a dozen times, so feel free to direct me there if you find it.

I just got done tuning me VE table using an LC1 WB O2 (this is a '99 Trans Am LS1, mods in sig). I got everything to within +/- 3% and everything was running great.

I noticed two problems though. When I start the car from a cold start, it runs TERRIBLY until it gets up to operating temp (this is with the MAF disabled still). What I mean is, if I give it gas it stumbles horribly and even full throttle it'll just stumble. This is wreaking havoc on my clutch because of having to feather the clutch until it grabs. Once I'm up to operating temp it runs awesome. I look at the log and it shows that the AFR error is REALLY lean at low temperature then it comes into line as it gets hotter and once up to operating temp it is within 3% error.

I can live with all that if that's the worst case, but it's not the worst case. Heh.

When I turned the MAF back on and started the car from a cold start, it just stumbles and dies. Even when I try to feather the gas a little it just dies. A scan shows MAX lean. I just turned the MAF off and drove the car to my mother's house. It's now up to operating temp. I turn the MAF back on and it will now run (not great), but it will run. I didn't try any tuning but I did run a quick scan and again, MAX lean.

Sorry for the random thoughts here and if needed I can post my tune and scan. I was more wondering if anyone knows of any reasons this could be happening in general. Is it purely because the MAF has not been tuned? Is it that the MAF could be bad? (It reads like it's working, but obviously that doesn't mean anything).

Could it be that the O2 sensor wasn't calibrated correctly? (like I accidentally did a calibration when the engine was on or something?). I'm just throwing out some ideas here.

Thanks a lot folks, I appreciate any advice. Please let me know of any information that could be helpful and I'll be sure to discuss.

B

BLK02WS6

iTrader: (2)

Post up the tune and a log.... stock MAF? When you converted it to an M6, did you full flash an M6 tune over the A4 tune?

Gatsby

iTrader: (7)

This is the tune (attached), I'll have to save a decent log for you, so please bear with me.

Stock MAF, never touched at all. I did NOT do a full flash to M6. I have always wondered if this could cause any real issues by me not doing that.

Thank you for your help. I will try to get a log posted soon.

Ed Wright

iTrader: (1)

How about loading stock VE tables, with the MAF back "on "?
Might be surprised.

BLK02WS6

iTrader: (2)

Your VE table looks like the Rocky Mountains... not trying to be a jerk, but its a mess. Wish you were using EFILive, would be a lot easier helping you out... I would also recommend full flashing it to an M6 OS.

edcmat-l1

iTrader: (10)

Your VE is beyond hideous.

The reason you're lean when it's cold is because you're commanding lean. You OLEQ table is set to .81 up to 158 deg. F.

Also, if you're having to command 1.16 and those numbers in the VE at WOT, you've got problems. You're probably loosing fuel pressure. Those numbers are so far from where they should be it's ridiculous.

Tune with cold problems_EH1.hpt

This tune has a "normal" OLEQ table in it. It should at least make it run a little better cold. I'll leave it up to you to fix everything else. Seems the car may have some issues preventing it from running on a "normal" VE.

Gatsby

iTrader: (7)

Thank you very much for your help folks. I don't take any offense to pointing out my mistakes as I'm obviously an amateur in every sense.

I will flash a stock M6 tune with the appropriate changes so that I can start semi-fresh. By looking at a stock VE table I see how awful mine is compared to what it "should" look like.

Seeing that OLEQ table was also helpful. When I was doing the VE tuning the guide I was following said to make everything 1.00 across the board. Is that JUST while I'm tuning? Or should I just leave it like stock and not do the 1.00 across the board.

Thanks a lot guys, I appreciate your time and efforts.

mshadow

The 1.00 across the board is just for tuning so your not chasing an ever changing target AFR

You're supposed to put it back

Gatsby

iTrader: (7)

Well that explains a lot. I'm sure to veteran tuners a lot of this is obvious, but in all of these guides there are very clear instructions on what to change/turn on/turn off, but never any mention of what should be left as is and what should be put back.

Thanks for the help, I'm going to go play with it right now.

B

Gatsby

iTrader: (7)

Along the same lines, do you guys put your STFT and LTFT back to Learn or do you leave them off? Or is that a matter of opinion?

BLK02WS6

iTrader: (2)

You really need to be careful of the information that you find floating around on the internet... even stickies on forums can contain some questionable information.... You need to understand what your actions are doing to the car - don't just follow it like a cookbook! If you are in over your head, maybe it is best to get some professional help to get it tuned now, and learn a little at a time.

Ed Wright

iTrader: (1)

^^^^^ Word!!

Exidous

iTrader: (11)

Generally speaking the LTFT's should not be needed as long as your tune is good. The STFT's are there to adjust for random transient movements of the AFR.

Many run LTFT off and STFT on.

Ed Wright

iTrader: (1)

Why in the world would anybody turn the long term trims off? That's just dumb.

Realcanuk

Many, including me turn them off because they carry over the last reading into PE when positive. I wouldnt say its dumb.

edcmat-l1

iTrader: (10)

Simple answer. If the tune is dialed in close enough, if there's less than 10% variation in fuel trims, LTFTs are not needed.

Ed Wright

iTrader: (1)

If it's tuned correctly there is no reason to turn them off.

Exidous

iTrader: (11)

The NB O2's have no place changing PE fueling. If GM in their infinite wisdom had let the LTFT's not affect PE I'd leave them on. They are great for small changes in weather and engine but I just don't want them messing with anything while my engine is working its hardest.

Example. If the O2's are going bad and pulling 10% fuel, I now have 10% less fuel at WOT.

Ed Wright

iTrader: (1)

Been tuning a lot of cars for a lot of years? Degraded O2s indicate lean, thus cause the PCM to ADD fuel, not pull fuel. Positive LTFTs will (if you don't know how to prevent it) add fuel in P.E. mode. Don't recall ever seeing one pull fuel in P.E. mode.

Thing to do is keep good O2s in the car.

sreve

iTrader: (3)

You need to do something with the timing tables asap 35* high and low
is way high.