85 Camaro 305 Check Engine Light Help!!

[bgtaylor]

So yesterday I washed/waxed the car and when I was finished, I took it for a drive. It began its normal idle routine after the wash, jumps up to 2000rpm and declines to 1250rpm or so. (This car has had an idle issue since the day my parents bought it so its normal since I've had it.) After driving it for a bit I realized the check engine light came on. The car, while in park, will idle at 2200 rpm consistently and will not come down. I have tried adjusting the TPS, but it is as low as it goes. My next step will be to check the IAC, but the car needs to cool down. I understand A vacuum leak could be an issue but I'll worry about that after the IAC. Also, I cannot adjust the idle screw because it is a new Throttle Body and it has some sort of lock tight on it preventing me from having enough leverage to adjust it. I used my fathers key as a scan so all possible codes would be flashed through the check engine light, but when I turn the key to the "on" position, without starting it, no codes are displayed. I checked it again about 15 minutes later and I got codes: 12 and 22. Anyone have any ideas?

All advice is greatly appreciated regarding the issue.

[Curt_irocz]

Replace the iac. I had a similar problem with my old 86 305 tpi.

[hoogiesngrinderz]

code 12 is normal, will always come up

code 22 is low TPS voltage.


Pull the IAC and clean/replace it, reinstall IAC. Jump A and B and turn key in the on position as to put the ECM in diagnostic mode. Turn the key off then unplug IAC. Start the car, set the idle to 600 rpm. Shut the car off and plug in the IAC. Turn the key on and adjust the TPS to .54 volts (ground in top pin, positive in the middle pin)

[2002Z4CSS]

Put a scan tool on it and look at the TPS voltage.