reventropy
01-02-2012, 06:46 PM
I have a 97 Legacy outback manual with a 2.5L engine. I was driving cross country when my speedometer and odometer stopped working. Check engine light came on. Shortly after I got home I noticed that the engine was idling low (4-500 RPMs). I later found that this only happens when the car is warm. When it's cold it idles ~1200 and then after about 5 minutes drops to about 400. I assume that the speedometer issue is just a speed sensor thing but I thought I would mention it just in case it's more than coincidence that these things happened together. I didn't see any noticeable loose vacuum tubes under the hood. The air filter was dirty so I put a new one in. I ran the codes and they were "engine idle", and "speed sensor" or something close to this (it's been a while). I finally up and removed the IAC after reading some forum posts. It has some carbon buildup but it isn't sticky. The coolant paths are also clear. I hooked it up to a battery to make sure that the valve actuates and it does fully open and close (at least at 12 volts). I also checked resistance with an ohm meter and got a reading of 9.6 Ohms across one motor winding. From where I'm standing it looks like the IAC is working fine, so I'm lost as to what could be causing the idle problem. Any help would be awesome! I thought it could be a low voltage short on the way to the IAC but I don't know what I should be reading for voltage at the connection. Thanks again.