My LT1 is ideling at 1500 RPM

[drexel_j]

I have a 1992 LT1 Crate engine that I put a Painless wiring harness on and I can't get it to idle. The only modification from stock is a Crane 227 cam. It starts fine but idles at 1500 to 1600 RPM; I have blocked off all of the vaccume ports and sprayed the intake with both water and WD-40 and it doesn't make any difference. I am running 22 LB injectors, all new sensors and had my chip burned by FIS out of SA, they told me the chip makes no difference untill the system goes into closed loop. I have long tube headers with the oxygen sensors in the collectors. Any ideas.

[theBrit]

I had the idle air control valve jam on me, basicaly it never moved and it was always letting in too much air. In my case it was broken, but I remember when I replaced it, it needed to calibrate its self, but I forget how you acomplish that.

[80LS1T]

Are you sure you have the correct harness for your 92 LT1. The 94+ have a different IAC sensor and if you dont wire it right it will idle just like your saying. I know you have a painless harness but you said you have all new sensors. I would check your IAC wiring from the connector to the PCM and make sure your wires are where they are supposed to be for that IAC. I had to switch wires on my IAC because I am using a 93 LT1 with a 95' PCM/Harness and the wiring isnt the same. My car idled just like yours before I figured out what the problem was. There was nothing that I could do to get my idle below 1100 RPMS before I fixed the wiring.

 

Guy

[drexel_j]

I was talking to a guy at FIS in SA and he had me look at the color code on the wires going the IAC and it turns out they were wrong, Painless wiring said they had a problem with some of the harness they made a few years back and told me how to correct it. I will report back when i fix the harness and see how it runs.