High idle problem. 5.0L HO engine

Check out the ten pin (black and white trash cans as they are sometimes called)connectors that connect the injector harness to the main harness. I always clean with some electrical parts cleaner and then add some dielectric grease.

Casey

It idles about 2000 rpm. At first it would only idle high a few seconds when you first started it up. Now it idles high, ALL the time.

I pulled apart a few wiring connectors and all the contacts look clean on the idle air solenoid, TPS and maf sensor.

What could be wrong and how should I check it?

Dan S

sometimes

Check your air control valve maybe its stuck . They do carbon up.

I unplugged the IAC while it was running. It made absolutely No = difference. Does this mean it is defective or just needs to be taken apart and = cleaned?

Dan

It means you still need to check it to see if it's stuck...... the springs in these are very weak and carbon can overpower the spring keeping the valve partially open. Though it looks like an electrical device, it is still very, very much a mechanical device. Similarly, vacuum leaks of any sort can result in "unauthorized" air that can and will drive the idle Rpm high.

Jim Warman snipped-for-privacy@telusplanet.net

Dan

Thanks. Now. How do I check to see if it is stuck? There doesn't seem to be anything in it I can move without risking damage. Is there a way I can acctuate it by putting 12v to the terminals or is

The parts store wants $75 for a new one and no refund on electrical parts.

Please explain in detail how I can check to see if it is stuck. What tools or devices do I use?

Dan

It may also be a leaking/stuck-open EGR valve. This usually sets a code 34, but not always, depending on the condition of the movement sensor. First thing when you have an idle/off-idle stumbling problem, ALWAYS pull the EGR and make sure it is clean and operates freely. On older engines, a piece of carbon can easily become embedded in the valve, causing it to stick open.

Regards,

-JD

--------------------------------- JD's Locally-Famous Mustang Page: http:/207.13.104.8/users/jdadams---------------------------------

Check for a vacuum leak. If you have no leak, the problem may be a sticking Idle air bypass valve. Also, make sure the throttle body doesn't have something making it hang open.

Steve B

It idles about 2000 rpm. At first it would only idle high a few seconds when you first started it up. Now it idles high, ALL the time.

I pulled apart a few wiring connectors and all the contacts look clean on the idle air solenoid, TPS and maf sensor.

What could be wrong and how should I check it?

Dan S