Having trouble lately with higher IAT

[spy2520]

For some reason I have noticed during the hotter days I have been having trouble keeping the car running. This happens both on cold starts and hot, and frequently when coming to a stop IF the car hasnt moved much, i.e. slowly moving through a parking lot. Sometimes I'm embarassingly starting the car 3 and 4 times before making i out of where I'm at. Haven't really been able to get a good log of it, but what i do know is if i get up to speed, slowing to a stop isn't really a problem. And when the ambient temps ar 5-10*F lower i don't really have a problem. Which makes me feel like it must be related to intake air temps.

All i can imagine is when i tuned the car it must have just been too cold to translate to good summer behavior. Could this just be a situation of needing more/less idle air?

This is on a 99 LS1 auto.

[joecar]

Sounds like idle tuning needs to be revisited: Idle-Tuning-Helpful-Info-Inside

[spy2520]

Yeah i spent a decent amount of time on that thread. Everything was good up until we started getting some hot weather. I dont drive the car as much so at first it seemed like a one-off. But it has happened several times now. Wondering if maybe the VE table is just not good in that area and its too rich with higher IATs.

[statesman]

Is this the same vehicle you were having problems with winter idle a couple of years ago?

[spy2520]

Yep. Maybe I'm bouncing between getting it running well in winter vs getting it running well in summer. Seems I had partially corrected a problem and created another.

[spy2520]

Anyway to put in perspective. It rained yesterday, and the car ran fine yesterday and today. But I'm sure if it gets over 90* again, I will have problems. I'll try to get logs and see what is going on.

[statesman]

If I remember correctly, you zero'd out your airflow corrections. I thought that might come back to bite you later, and it looks like it has. You really need to have perfect desired airflow when doing something like that to your tune. Re-visit your desired airflow when the temperature gets hot enough to cause you problems.

[spy2520]

Yeah that zeroing was a temporary experiment. The tables have since been repopulated with stock data and then massaged based on the idle tips. I have attached what was ironically named "known good tune" which i guess i have to add "formerly known as" in front of that.

[statesman]

Okay... I've had a look at your tune file. I'm amazed that the engine actually runs at all on this tune. Can you give me a list of mods?

[spy2520]

Lol. Cam is 236/338 I think. 3500 stall converter. Fast 102. 102 throttle body. 1 7/8 headers. I think that's it.