Had to remove my IAC and TPS for other reasons and I read article in the tech section but still a little confused!

Should I adjust the Iac first or the tps?

I tried the IAC and the car idled at 550 nicely but as soon as I plugged the IAC back in it would idle back at 1500 (way to high)

I have a little digital pocket meter so which setting do I use to set TPS? AC DC CHECK K Thats whats on the meter?

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1985 Camaro Iroc Z
305 Tuned Port Injected

 

I would start with the IAC first, and the best way to get it right is the following procedure from the GM service manual:

Oh, and plug it in before you do this - "The IAC can be reset by depressing the accelerator pedal slightly, start and run engine for five seconds, then turn ignition OFF for ten seconds"

After that, just restart it and make sure it set right. It is self-adjusting by this procedure, however, if you disconnect it with the engine running the speed will be set wrong, which is probably your problem. Just follow that procedure and you should be OK.

Now you can set the TPS properly using the method in the tech section, set your pocket meter to "DC" since it's a DC system and you want to check the output voltage. Hope this helps.

 

I adjusted my Iac as it says in the tech section and also my TPS with DC and while i adjust the iac I get the idle down to 500 and it idles nice and smooth then after i hook the iac back up i start it and it idles nice and smooth the first time but after that every other time i start it it idles at 1500 rpm! some times it lowers to 1000 rpm?

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1985 Camaro Iroc Z
305 Tuned Port Injected

 

I would pull the IAC housing from the bottom of the throttle body and make sure you don't have an a$$load of buildup in there. Clean the IAC pintle and the housing with some good carb cleaner spray and let it dry. Make sure you hold the IAC motor with the pintle facing down when you spray it so that it doesn't get into the internals, put it all back together, and follow the procedures outlined in the tech section, and you should be ok.... let me know if you need more help.

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Kevin Irving
85 Trans Am WS-6, 305 TPI, custom burned '86 PROM with '87 "165"ECM, Accel Supercoil & 8.8 Wires, MSD 6AL, Aluminum Driveshaft, TB Coolant Bypass, Ported Plenum, Modified MAF, Syclone Fuel Pump, JET Airfoil

15.556 @ 86.65mph, Nov 10, 2000.... I know it sucks.. but it will get better!

http://www.geocities.com/transam85tpi/

 

took out IAC and cleaned out the passage but didn't help my car still idles at 1000 - 1500 rpm. (but definetly needed a cleaning)

Could my ecm be bad? How can I tell if the ecm and prom are stock? The guy i bought thr car from said he replaced the ecm and i was wondering if maybe he put the wrong ecm or prom in? Ifso would that cause idle to stay high!!

I can get my codes with the jumper wire but the scanner wouldn't pick anything up?

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1985 Camaro Iroc Z
305 Tuned Port Injected

 

Also why does the fan come on when I check codes with a jumper wire?

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1985 Camaro Iroc Z
305 Tuned Port Injected

 

It is normal for the fans to come on during the diagnostic jumpering.

Double check to make sure that the throttle body is fully closing. Sometimes they stick so by hand make sure it is fully closed.

When you adjust the base idle, make sure you jumper the diagnostic connector, turn the key forward (without cranking) and wait about 30 seconds (the fans will be running). You must wait to make sure that the IAC pintle is fully seated, thus no extra idle air going by. Then while the key is still forward unplug the IAC. Now remove the jumper (fans will now go off) and then start the car. Now you can set your base idle. When done shut off the car. Then reconnect the IAC. Now turn the key forward again (without starting) and adjust the TPS.

Note: Do this procedure when the engine is at normal operating temp.

 

Hey, I've got a similar problem, and need to reset both the IAC and TPS.

I suspect there is an a$$load of buildup in the same area. Is it worth pulling the whole frigging TB and dunking it in solvent to get it all out?

Sounds like our guy here has some coked plates.

Also, does the TPS setting affect this? Seems like when the full system is engaged, there is some signal to the IAC to bypass some more air, giving the 1000-1500 rpm rise.

And is there any simple-to-follow procedure for setting timing? Mind feels as retarded as ... well, I ain't going there.



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Bob
'87 Formula TPI 5-speed

 

If you do have a problem with a "sticky" throttle body, I would try to clean it real good first to see if that helps. If that still doesn't help, like mine, than you can add a helper spring to help close the throttle. I used a simple carb. return spring.



[This message has been edited by TunedPort350 (edited March 15, 2001).]