Uber low idle when warmed up.
Posted: January 18th, 2009, 11:11 pm
A while ago I started having issues with charge light coming on when running cooling fans and/or A/C. I thought it was the alternator, but now I think I figured it out - my idle is too low. When fully warmed up (maybe 5 - 10 minutes of driving), my idle is at around 400 or so, and if the engine is running a bit warmer, it's even lower. Car doesn't stall, in fact it idles smoothly (which is probably why I haven't noticed that it's so low), but if I turn on cooling fans or run A/C, my charge light comes on after a few minutes. I guess the alternator is not spinning fast enough to compensate, so it starts to drain the battery. If I gently hold down the throttle to bring the idle speed to above 700, charge light goes off.
Since this is a relatively recent development, as the car used to idle at around 600-700 last year, and I haven't played around with idle adjustments to cause anything of the sort, I suppose something is going bad. First thing I thought about was the IAC, however I'm not sure what resistance it's supposed to have when warmed up... FSM says 10-12 ohms at 20C, but does the resistance go up or down when it's hot? I just measured about 13.5 after driving and then letting the car sit for 10-15 minutes or so. Is that within spec?
Since this is a relatively recent development, as the car used to idle at around 600-700 last year, and I haven't played around with idle adjustments to cause anything of the sort, I suppose something is going bad. First thing I thought about was the IAC, however I'm not sure what resistance it's supposed to have when warmed up... FSM says 10-12 ohms at 20C, but does the resistance go up or down when it's hot? I just measured about 13.5 after driving and then letting the car sit for 10-15 minutes or so. Is that within spec?