Idle high until i tap the throttle
 

Hey guys, trying to get some ideas here. Car runs fine with the exception of high idle on occasion. Ill push the clutch in and sometimes the RPMs will be as high as 3k, tap the throttle and it drops to 1kish. In gear i can tell when its sticking too. its almost like a cruise control lol.

I tested the TPS and it was bad but after replacing it still has the same issue, the TB looks clean and i cannot find anything binding in the throttle linkage. Any other ideas?

Could we get a hint on the engine and year?

Sorry its a 93 with the 5.7

IAC can be dirty or it is getting lazy. Search cleaning LT1 IAC and relearning LT1 IAC.

This is routine maintenance so I would do that first. The next question is the ECM telling the IAC to do this or is it trying to close the IAC and its just not closing fast enough.

Either dirt or laziness are common issues. You also want to be sure the throttle is returning freely to its home position. Binding can be hard to feel and you have vacuum pulling on the throttle body while its running. You can use a feeler gage between the screw and throttle plate adjustment to make sure it is closing.

The next step would be to verify where the air is coming from. An engine needs air to rev so where is the air coming from if not from the throttle body.

make sure transmission cable is not hanging up and holding the throttle linkage up. maybe open hood and see if you can get it to do it while you are watching to see if linkage or throttle body is hanging up somehow.

Well i went to clean the IAC and as i took the electrical connector off the thing started falling apart in my hands, so i went ahead and bought a new one. I tried the reset procedure. Ignition on foot lightly on the gas start it release gas wait 5 seconds then turn off for 10 and turn back on. Idle is better but still all over the place. Kicking up to 2k sometimes and most of the time it just hangs at 1500 now. but if i tap the gas then wait it will change, each time it seems to be different. Sometimes stops at 1200ish sometimes at 1k, sometimes around 900. but nearly everytime i come to a stop and release the clutch it kicks up to between 1500 and 2k.

Did i do the reset wrong? I could only find a couple of places that explained it and how i did it is what i got out of the explanations. Is there a TPS reset as well?

I cant find any vacuum leaks or hang ups in the throttle cables.

Not sue if the TPS is adjustable on the 93. The best way to check it is look at the input that the ECM is seeing. Manual should have a ohms setting spec.

Like I said above, next you should use a .003-.005" feeler gauge and try to slide it between the throttle stop and the Throttle lever. After you rev the motor check it again. If the feeler gage slides between the throttle stops when the engine is at the higher RPMs then you know your issue is in the throttle mechanics. After that I would disconnect the throttle cable and retest it. Who knows a helper spring may be all you need.

After that find a way to stop the air flow into the throttle and see if you can stall the motor out when it is at high RPMs. If it does not stall right away, you have air leaking into the system from somewhere.

you can round out the holes oblong to get a small amount of adjustment on the tps

link to adjusting tps https://camaroforums.com/forum/93-02...-sensor-70605/

make sure the intake manifold bolts are torqued properly, I had mine loosen once. so bad oil was getting into the intake from the engine valley.