I have the Comp Cams 270H. Specs are in the sig. My idle speed is 1500 RPM. I've tried lowering it in the PROM but it has no effect. I know I am doing that correctly because any other changes I make in the PROM have noticeable effects. I figured I probably had a vacuum leak, but I sprayed starting fluid everywhere and I mean everywhere. The idle didn't change at all. I've turned the idle screw back and it doesn't change anything. The IAC is about a year old and I'm pretty sure the passages are clean. I have a strong feeling that the problem is the TPS. I have tried setting it numerous times and the voltages that I get never make any sense. They are always like .048 instead of like .54. When I check it for resistance as I open and close the throttle, the numbers increase and decrease smoothly and linearly. I have 5 volts input. Can anyone give me any tips on what to do?

Also when the car is running if I loosen the TPS screws and move it back and forth it has no effect.

 

Any error codes?

Are the throttle plates possibly binding? Brake booster leaking (cap the line for testing)? Correct PCV? MAF reading correct?

 

No error codes. The throttle blades aren't sticking. I have the correct PCV. The brake booster could be leaking, I'll check that. I don't know if the MAF is reading correctly, but it seems to be normal (ie no bucking or surging, smooth) through all RPMs except idle.

I don't know what to think of it. The past few days it has actually idled really low, like near 500, then the IAC opens up and it revs to about 1000, then dies back down, revs up. I may have set the idle too low in the chip, I'll try setting it at about 750 and richening it up a little, it is reading very lean on the wideband at idle.