Removed my IAC to check and my plunger does not move, is this normal?

 

I have never had the IAC valve out of a GM vehicle. That said it is a bi-directional stepper motor and as such I would expect the plunger to be very stiff when unplugged. Unfortunately the test procedure involves a high end bidirectional scanner to command the IAC to test it.

George

 

I'm not sure the IACs normally moves freely or even with difficulty. I've played with them a couple times, and in my experience the plunger does not move easily. Like George says, you need a high end scanner to test it properly.

 

The shaft was pretty mucked up, got it clean with carb cleaner, the throttle body was loose enough to see the IAC move back and forth with power applied so at least now it appears to be working. Going for a test drive here in a minute.

 

Was it not working visually with power applied before you cleaned it?


George

 

Unfortunately I did not check before removing.
Okay here are the results from this afternoon test drive, about 15 miles one way, several miles of flat road then hilly, ran great, smooth shifting, good power, no Service Soon light. Parked about 30 minutes, started right up and again was running great, coming down a long hill, very light on the throttle, here comes the Service Engine Soon light flashing for about 12/16 times then stays lit rest of the way. No change in the performance, no stumbling, still shifting good. Parked at the house an the RPM did raise to 1000 and stayed there, scanner showed my old friend P0300.
Can have a friend of a friend hook it to his pro level machine later this week for a complete scan reading.
Any thoughts? Oh let me add I did install a new coil before the drive.

 

I’m heading back over to the other thread to keep this story in tact for us and future readers. I’ll post there in a bit.

George