Lately my car's been idling rough. It'll sit in the 200-300 rpm range and kind of bounce every once in a while. I'm thinking maybe the MAF's clogged or the air filter needs to be replaced. Anybody know what else this may be from?
Though, Haulin was wrong about adjusting the idle. The butterfly valve has nothing to do with the idle speed. It's just there to reduce low RPM engine noise. It opens between 3000-4000 RPM to let more air into the engine, and there is no adjustment for it (it's controlled by the engine's vacuum). The only way you can adjust the idle on the Celica is to get the Apexi PowerFC. The idle is controlled entirely by the ECU, so even tightening the throttle cable to increase it will be cancelled out by the ECU closing up the IAC to compensate. It's not instantaneous, but the ECU will catch on after a little while and reset it back to OEM specs.
Yes, I had the IAC acronym misordered. However I AM NOT WRONG about the butterfly valve. Do your homework. Ask anyone what happens when you manually open the butter fly. The engine revs up. Your throttle cable is attached & so is the throttle position sensor which tells your computer how much throttle you are seeking & it lets more fuel out the injectors. This screw is a idle adjustment screw. Its on both the GT & GTS; maybe not DBW versions, I donno.
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