IAC counts too low at hot idle

[96LT4C4]

I am having an issue where I have to crack the TB open more when the car is cold to get it to start good with out maxing the IAC out to 310. Say if the TB is set to .5 volts I have to open it up to about .57 to .6 to get it to start good cold. Then if I let the car sit and idle till its as hot as its going to get my IAC counts go all the way to zero. I have tried playing around with the timing to get the idle to drop so the IAC will open up some. I did that at the end of this log to show that.

I have been running the car at 17 degrees timing at idle to keep some IAC counts but I would like to raise up to about 22 degrees for a smoother idle.

I think my log was with the timing at 22 degrees, at the end of the log I used the VCM controls to lower the timing to 17 degrees. Is there a chance that the FAST 102 TB could be causing all this? Do I need a smaller TB.

[jimmyblue]

Most likely if you can't get the car to run cold with
that much air, you're overfueling it. All the adders
just stack up. What's your commanded AFR and your
indicated AFR when you are having this kind of trouble?

[david_viny]

You're tunes are tuner locked fyi. I would GUESS that you could close the throttle body some, and then fix the idle base running air flow because it looks waaaay off when its cold. It looks like it doesnt really need the high IAC counts when cold, it just starts high and then the STIT trim it down a ton since BRAF is off.

[96LT4C4]

Well, was tuning my VE tables with the LTFT and STFT fuel trims to get my VE dialed in. It seemed like when my fuel trims were almost perfect at idle hot, it would be lean causing it to surge. when I started it cold watching the wide band. All my open loop idle tables are pretty much stock so the commanded AFR should be stock.

Right now my LTFT are subtracting around 9 percent at idle.

[96LT4C4]

I cant figure out how to unlock my tune, I am not real sure how it got that way in the first place.

[96LT4C4]

If i close the throttle it starts then imendiatlly stumbles and the IAC starts to add air to keep the car running, thats why I have some much air in my BRAF table.

[david_viny]

I think unlocking the tune is under edit > calibration details - then clicking the unlock icon on top left.

[96LT4C4]

Thanks, here you go

[96LT4C4]

Started the car last night cold, it fired idle dipped just for a second, then it recovered and idled good. The wide band showed 13.9-14.0 AFR. I wasn't logging just wanted to see how it did. The bad thing about my wide band is I can not see if it is fuel causing that initial dip because cranking the car resets the wideband and it takes about 30 seconds for it to warm back up and start showing AFR. May need to hook it to an external power source.

The TB is still cracked open a good bit, up from .50 to .575 volts.

I am pretty sure the dip is the PCM still adding more air to get it to idle.

[96LT4C4]

Anybody got any more ideas?

I am going to try and start it to day. I am going to raise and lower the fuel AFR with the VCM controls and see what it does to the IAC counts.

[monte4ever]

Did u solve this issue?