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Hey guys I have a 2010 Chevy Cobalt LT 2.2L sedan with the LAP motor. So far I have added a custom cold air intake using a k&n cone and a zzp high flow intake tube maf extension harness with a homemade dual walled heat shield/air dam, I have also added zzp shorty headers, zzp 3 inch Inner Diameter downpipe with single cat, and a 2.25" catback from dnr. A zzp fuel pump rewire kit and a 4 bar map sensor from zzp with the ecu reflashed with the proper parameters for that specific part both linear and offset were the only 2 things changed. Other than that the cars internals and tune are stock. I just ported my throttle body and now the car is failing to relearn idle position, cold start idles at 1200 to 1450 rpm and after driving if you shift back to park It jumps from 1200 up to 1600 and 1800 and holds. I've got hp tuners mpvi2 an the cars licensed, please help I've checked for vaccuum leaks and loose spark plugs, fuel pressure is fine, short term fuel trims are fluxuatingat idle between -5 and 1% at 1600 rpm idle spark stays around 5degrees I've tried the idle relearn for gm 3 times with no luck, unplugged ecu fuse 30 mins, did relearn again still no better. M idle maximum setpoint appears to be 1400rpm would lowering this be beneficial or should I look at rescaling maf table a bit higher as I believe maybe I took a bit more than I though out and th motor is still sucking more air than expected with no throttle?
I suspect you have leakage around the butterfly/throttle blade and the body.
Did you remove the butterfly when doing the re-working and/or remove material in the area(s) where the blade would normally come close to the body? If so, did you check it was correctly aligned before screwing it home?
You can check by removing it, the assembly, and holding it up to the light in the closed position - there should be no light visible if the engine uses a bypass/air bleed, and almost nothing if it has a stop - I assume if it has, it isn't adjustable?