09-02-2017, 04:17 AM
Update: I removed the IAC valve. It was pretty clean internally, but I cleaned the shaft with some carb cleaner and reinstalled it. There must have been some recalibration going on, because it took 2 engine start/run trip cycles to settle down to what I consider normal idle behavior.
After warm up, the first start/run trip cycle had the idle rpm racing up between shifts (rpms rose to about 1600 rpm between/during shifts with clutch pedal depressed.)
After the engine cooled off, a second trip cycle revealed idle rpm revving (surging) up and down slightly between 750 rpm to 900 rpm.
After the third trip cycle the idle has became steady, with headlights and blower fan off. The car now demonstrates a predictable dashpot behavior between shifts. The rpm no longer drops off suddenly when lifting the gas pedal during shifts. If the engine is revved while the car is stationary, the idle takes about 2-3 seconds to return slowly to 750 rpm.
Thanks again Fixkick! For future reference, is using carb cleaner the best way to internally clean the IAC valve?
After warm up, the first start/run trip cycle had the idle rpm racing up between shifts (rpms rose to about 1600 rpm between/during shifts with clutch pedal depressed.)
After the engine cooled off, a second trip cycle revealed idle rpm revving (surging) up and down slightly between 750 rpm to 900 rpm.
After the third trip cycle the idle has became steady, with headlights and blower fan off. The car now demonstrates a predictable dashpot behavior between shifts. The rpm no longer drops off suddenly when lifting the gas pedal during shifts. If the engine is revved while the car is stationary, the idle takes about 2-3 seconds to return slowly to 750 rpm.
Thanks again Fixkick! For future reference, is using carb cleaner the best way to internally clean the IAC valve?