A couple of days ago the idle went from around 900 to 1800 and stays there. I had some spares so replaced the TPS and water temp sending unit, removed throttle body and cleaned it, removed EGR and checked it. Checked for vacuum leaks, checked PCV valve. No joy. Not a linkage problem by the way. Any ideas? Thanks.
-- Country people don't shine their boots very often, but then they don't shine anyone else's either.
Does it have an idle air bypass valve on it? It may be stuck open.
Spdloader
No, I checked and cleaned it. Solenoid could be bad that operates it though I guess. I know I can pull the wires off of it and the idle doesn't change.
If it's stuck, pulling the wires won't change it, but that doesn't mean it's bad either. When you have it off, can you move the valve inside? I think I'd disconnect the solenoid and start the truck, make engine changes with the throttle, and see if the solenoid is working.
Good luck man,
Spdloader
Yes, I pulled the valve off and cleaned it so I know it isn't stuck. Like I said, I wonder if the solenoid could be bad? Could I tell by pulling it off, starting the truck and seeing if the plunger is moving?
If unplugging the IAC doesn't change the idle you have 1 of 3 possible problems.
Throttle isn't stuck and hasn't been adjusted, IAC isn't stuck so I am going to check for a vacuum leak later today. Thanks.
Prime suspect for a vacuum leak that large is the gasket between the upper and lower intake manifolds. Fairly common and would explain sudden appearance of condition.
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