Hey guys I have a 1990 GTA with a 350 and it has started doing this weird thing on the first cold start of the day.
When I start it it takes at least 5 seconds of cranking to start then the idle is rough up and down from 500 to 1000 rpm until it goes in to closed loop at which point it revs its self to 1500 rpm and drops to 650 rpm and idles totally smooth.
Every other start of the day is fine instantly starts and settles right in to a smooth idle.


It has new bosch III injectors, fuel pressure regulator, fuel filter, iac,tps, coil, cap, rotor, wires, plugs and o2 sensor
I checked for vacuum leaks 3 diffrent times and found nothing.

Any idea what would cause this?

 

Here's an old video of the problem.(sorry about the quality old camera)
Trying to upload a new video now.

http://youtu.be/JTVEMEJpgfw

New video

https://www.youtube.com/watch?v=9WK-...e_gdata_player

 

If you figure it out let me know. Iv been dealing with the same thing for a year and have found no solution

 

Got the same issue with mine, going to start this weekend on IAC, TPS, Plugs n' Wires, and check Fuel Pressure. If I find the issue I am having I will post my fix on it as soon as I locate it.

 

let me know if you figure it out. so far iv changed IAC, CTS, full tune up, going for longshot and replacing o2 sensor next.... im stumped

 

Cold idle and O2 sensor have nothing to do with each other. Open Loop

 

Hi guys I never did figure out the problem it has just become part of the routine
start it up let it run till it goes in to closed loop then it revs one time to about 1500.
Then its ready to drive and runs fine for the rest of the day.

If anybody figures it out please let me know.

 

insomniac, you need to start a thread in diy prom. I think you should also repost the video The desired rpm seemed to low and you need to work on your start up enrichment I can't remember but I think it was too rich. Start pulling ve from the lower rpm and see if that helps.

 

I 100% agree. However in another thread someone GD said they had the same problem, tried everything. Then just changed the o2 for the he'll of it and it fixed the problem. So before i go nuts or even more nuts Im investing the 15 bucks and10 minutes.

Using search seams to be a common problem no one has gotten to th bottom of.

 

Will do

 

Im thinking you might fool around with idle RPM Dead band values. This allows for the idle to vary from the desired value. This prevents the IAC from continuously hunting.

 

I have the TPI sytem with the EGR under the intake and changed it out with cleaning the entire system while it was dis-assembled. No real change and my check engine light kicks on after about 10-15min driving still and it has weird erratic idle when sitting. So changing out MAP, IAC and TPS next week. EGA did NOT fix mine, on a side note the previous EGR looked replaced-almost new.

 

eh wasnt the throttle body did it again this morning, but not as bad... tuning next

 

think i figured it out. i changed my throttle body toa 52mm this past weekend. it stalled once on monday but has been fine all week. now im not saying you need to change to a 52mm throttle body but my guess is the iac passages are clogged... id say mine is 95% BETTER