I have an 02 ZO6 that I put a 232/236 580/580 112 cam in and I have gotten it to idle pretty well except whan restarting the car when it is warm. Added approximately 4 g/sec to the whole RAF table and set it to idle at 950 RPM and the closed thottle advance is 20 deg. It will fire right up and idle fine whan cold but if I start it when warm it dips to 200 rpm and will take about 10 sec to recover then it finally "catchs" and will idle and run fine. Anyone know which table I need to look at to correct this. I'm using HPTuners. Already tried increasing the IAC park positon. And I tried turning off the start-up flare control. Also tried increasing the ST adapt airflow max. None of these helped. When the stalling occurs the rpms dip to 200 and the STIT's go to +7 to +8 to try to recover. After 5-10 sec it recovers and the the LTIT is about -0.50 g/sec and the STIT hovers around 0.00 g/sec. So what is happening to it on warm start up that makes it want to die once before it can then idle normal. Obviously it's temp. dependent because it's fine on cold start. BTW the LTFT and STFT fueling is fine.

 

Also remember this is a fly-by-wire car. TIA

 

what are your IAT's during warm restart?

 

The IAT is right around 100 F

 

Might it have something to do with the "afterstart enrichment"?

 

hmmm

 

it's possible you IAT is a bit head soaked causing the startup issues. for grins, take her around the block (make sure everything is up to normal operating temp) and when you get back, pop the hood and point a fan to the IAT sensor. Give it a few minutes, 2 or 3, then try the hot start.

 

The IAT vs afterstart enrichment is all "0"s in the stock ZO6 file. I did change the Afterstart enrichment vs. ECT to all 0's after 111 deg and that seem to help a bit but not completly. On startup it is still commanding 13.0 AFR for the first 10 sec. That is when the stalling is happening. Once the commanded AFR starts to lean out the engine comes up to normal RPM. So what else is adding fuel for the first 10 sec besides the afterstart enrichment.

Also the Hotsoak table is all 0's in the stock ZO6 file already.

 

Try leaning out your Cranking VE by same percentage as current VE vs stock VE.
If Current Main VE is 70% of stock Main VE at idle then reduce the Cranking VE to 70% of stock Cranking VE. Too much fuel at startup was my problem with warm starts - leaned it out and it's cured. 2001 C5 239/251, 106. FWIW.

 

I made some progress today by reducing the "prime runtime" to 0 above 111 deg. That seemed to work and it doesn't try to flood on start up. Should I have corrected the cranking fuel in the cranking VE table instead? By doing what I did, it essentially turned off the prime pulse completly

 

Excellent! More than one way to skin a cat.

 

Well it's not completly fixed. But much better. Most starts are OK but sometimes warm starts if the car was just running still try to dump a bunch of fuel for the first 10 sec. I can watch the inj pulse widths go as high as 10 msec right after start(way too much for an idle condition). As soon as the pulse widths return to a normal range the idles stabilizes. So what am I missing. Something is still dumping fuel right after start. So far turned off the ASE and the Prime runtime.

 

To get my 2001 ZO6 with a 234/228/.573 SLP/COMP cam to start and idle better, I did the following:
Set the base timing to 38*
Set the start up airflow to 2.0 g/sec at all temps
Set the start up airflow delay to 100 camshaft revs.
Set the LTFT rpm boundaries to 1150,1600 & 2400
Set the LTFT map boundaries to 50,65 & 85
Disabled the throttle cracker.

Russ Kemp

 

This some how didn't updated when posted

Russ Kemp

 

Did you adjust Cranking VE???

 

Have you tried moving your IAT Vs ECT bias to 1.0 across the board?

 

Jumping in on this thread...

 

I don't find this in HPTuners. Where is it.

 

I changed the prime runtime to 0 after about 111 deg and that helped but it
still will try to flood sometimes on start up. I got my freinds TA with the same cam and Trick Flow heads and FAST 90/90 idleing
perfect last night. It wouldn't idle at all or even start without
feathering the peddle alot. But I did some of the same things I've done on
mine to it, plus played with the VE table in the idle region and now you can
just click the ignition once and it fires perfectly and instantly reachs a
stable idle. I think if I do the same to the VE table on mine it will run
as well. Going to try that tonight.