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Re: who here really knows their stuff?! Posted by Justin VanAbrahams [Email] ![]() ![]() In Reply to: who here really knows their stuff?!, s.martin, Mon, 27 Feb 2006 15:15:31 Members do not see ads below this line. - Help Keep This Site Online - Signup |
HA! I have so been exactly where you are.
I converted an '87 900Tc to LH2.4, did everything exactly the same as my '86 900S and my '80 900 16vT and ended up with EXACTLY the same symptoms you did.
Everything had run totally fine with 2.2, and I was kicking myself for the upgrade, as no amount of swapping AICs, ECUs, or literally every other component resulted in any change. You can ask damiens (on this board) about my grief on the top.
You know what the problem was? The PO had overadjusted the throttle position sensor so that "at rest" it was actually holding the throttle plate open ever so slightly, enough to bump the idle up to 1200. I only found this out after pulling the throttlebody and holding it up to the light so I could see it wasn't closing entirely.
ALL THAT SAID, this may not be your problem. My *recollection* is that the AIC sees ~8v at normal idle, but the more voltage it gets the wider open it goes and the lower the voltage the more it's trying to reduce idle speed. So with that information, it *seems* that your computer is bumping up the idle for some unknown reason. Possible causes include a wacked out AMM or an O2 sensor out of spec, or as others have suggested a bad ECU. Have you pulled codes to see if there are any that would help? FWIW, 1200rpm is about the limit of the AIC's ability to set idle...
posted by 216.57....
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