TPI IAC (Idle Air Control) issues
08-19-2003, 10:51 PM
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TPI IAC (Idle Air Control) issues
I'm ready to drive my camaro into a bridge. :mad
The car idles poorly when it's cold, and the IAC isn't doing what it should. So far I've replaced the IAC (twice), the ECM, the throttle body, tested the wiring harness, and gone through the procedure to set the idle 20 times. Nothing is helping.
When I start the car, it wants to idle at 500 rpms. My car won't idle at 500 rpms with the cam. I need to hold the throttle at a higher rpm until the car starts to warm up. IAC counts sit pegged at 160. Once it warms up a little, it'll idle on its own, with the IAC counts still pegged. Once it hits closed loop, the idle will smooth out a little bit.
Once I was in closed loop, I noticed that my IAC counts were rock steady at 151. I turned the idle up a little bit to bring it up beyond the "desired" idle rpm. IAC counts slowly began to fall. It took about 5 minutes for the IAC counts to fall to 0 and stay there. I backed off on the throttle slightly, and they slowly began to rise. They got to 35 and my fan came on. They kept going up into the 50s when my scan tool decided to turn stupid and stop communicating with the ALDL. I couldn't re-establish communication, threw a hissy fit, and decided to drink beer instead of fight with the car.
Does anybody have any suggestions here? I've exhausted all possible options as far as I can see, and yet my IAC will not play nice. It won't do what it's supposed to, and the car idles poorly and throttle response sucks. I'm at whit's end here.
BTW, the car is an 85 IROC, but I"m running a 165 ECM. 350, mods, 5 speed. Cam is a 214/224 .442/.465 112lsa. I've burned my own chip, but it's basically an APYP bin (89 6-speed Vette) that's had a couple constants changed.
Any help would be appreciated. This is driving me crazy.
[Modified by Jim85IROC, 9:52 PM 8/19/2003]
The car idles poorly when it's cold, and the IAC isn't doing what it should. So far I've replaced the IAC (twice), the ECM, the throttle body, tested the wiring harness, and gone through the procedure to set the idle 20 times. Nothing is helping.
When I start the car, it wants to idle at 500 rpms. My car won't idle at 500 rpms with the cam. I need to hold the throttle at a higher rpm until the car starts to warm up. IAC counts sit pegged at 160. Once it warms up a little, it'll idle on its own, with the IAC counts still pegged. Once it hits closed loop, the idle will smooth out a little bit.
Once I was in closed loop, I noticed that my IAC counts were rock steady at 151. I turned the idle up a little bit to bring it up beyond the "desired" idle rpm. IAC counts slowly began to fall. It took about 5 minutes for the IAC counts to fall to 0 and stay there. I backed off on the throttle slightly, and they slowly began to rise. They got to 35 and my fan came on. They kept going up into the 50s when my scan tool decided to turn stupid and stop communicating with the ALDL. I couldn't re-establish communication, threw a hissy fit, and decided to drink beer instead of fight with the car.
Does anybody have any suggestions here? I've exhausted all possible options as far as I can see, and yet my IAC will not play nice. It won't do what it's supposed to, and the car idles poorly and throttle response sucks. I'm at whit's end here.
BTW, the car is an 85 IROC, but I"m running a 165 ECM. 350, mods, 5 speed. Cam is a 214/224 .442/.465 112lsa. I've burned my own chip, but it's basically an APYP bin (89 6-speed Vette) that's had a couple constants changed.
Any help would be appreciated. This is driving me crazy.
[Modified by Jim85IROC, 9:52 PM 8/19/2003]
08-19-2003, 11:17 PM
#2
Melting Slicks
Re: TPI IAC (Idle Air Control) issues (Jim85IROC)
How are you BLMs in closed loop? Should be near 128 (normal) You may need to recalibrate the MAF table in the idle load area to get your mixture in line.
I set my desired idle to 900 rpm for normal temps, primarily to keep my alternator from dropping out with pulleys, this by itself helped alot with my idle problems. I also set my IAC table at 80 counts minimum. You may want to open up on the throttle stop for more airflow, but watch the tps adjustment. Good luck.
I set my desired idle to 900 rpm for normal temps, primarily to keep my alternator from dropping out with pulleys, this by itself helped alot with my idle problems. I also set my IAC table at 80 counts minimum. You may want to open up on the throttle stop for more airflow, but watch the tps adjustment. Good luck.
08-20-2003, 12:11 AM
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Re: TPI IAC (Idle Air Control) issues (Jim85IROC)
When in doubt install the OEM chip, if possible with your motor mods.
If you still have an IAC counts problem I suspect an air leak.
Also, check the coolant temps to see if they look right.
Check out the cold start injector circuit to see how long it's dumping fuel after a cold startup.
If you still have an IAC counts problem I suspect an air leak.
Also, check the coolant temps to see if they look right.
Check out the cold start injector circuit to see how long it's dumping fuel after a cold startup.
08-20-2003, 09:20 AM
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Re: TPI IAC (65Z01)
BLMs at idle are 118. Not ideal, but not bad enough to cause this kind of problem I think.
Coolant temps are fine.
I've eliminated the cold start injector, and the chip I'm running is a slightly modified 89 6-speed Vette file, which is really about the closest I can get. A buddy made a few changes to my chip that helped. I think it's time to find out what changes he made so I can keep going with them...
Coolant temps are fine.
I've eliminated the cold start injector, and the chip I'm running is a slightly modified 89 6-speed Vette file, which is really about the closest I can get. A buddy made a few changes to my chip that helped. I think it's time to find out what changes he made so I can keep going with them...
