IAC Issues

[Bake]

1993 Legacy 2.2L Normal breather.

Here is what I know so far - The other day when starting her up the idle went to 2200 rpm for 30 sec or so and then dropped to 1200 rpm. Checked codes and found codes 24 - Idle Air Control Valve & 32 - 02 sensor. The IAC seemed like the logical place to start the troubleshooting since the 02 sensor does not factor in on a cold engine or at least I don't think it does. Anyways, I checked voltage at the IAC connector and got .5 volts on pin A, 12 volts on pin B, and 0 volts on pin C. I measured the resistance values between all three pins on the valve itself and read 7 to 13 ohms between them and measuring from the pins to ground I got >1 mega-ohm. I thought maybe the valve itself was sticking, so I removed it to clean it out. When I had it off, I bench check the valve with an exteranl 12v dc source and the motor drives the valve closed with no problem.

 

So here is where I am getting stumped - there seems to be a good voltage source to the valve when the ignition is turned on, yet the vavle does not close when connected to the elec harness on the car. Also when the ignition is turned off there remains 12v dc applied to the B pin on the connector of the harness for approx 2 min's and then drops to 0 v.

 

Any Ideas??

If it helps,the IAC on this engine is of the rotary valve type and not the solenoid poppet valve type. I hate to "shotgun" a $340 valve at it and not have it work - since most places won't take it back once its been connected to an electrical source.

[Gloyale]

It is fairly normal for a Subaru to *high idle* for a few minutes. the fact that it went up to 2200 then came back down is a good sign.

 

Is it REALLY a problem? causing any drivability issues? Does the idle ever drop down to under 1000? when warmed up?