Survivalist 2011-11-04 23:03:20
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
Country people don’t shine their boots very often, but then they don’t shine
anyone else’s either.
Spdloader 2011-11-04 23:03:22
Does it have an idle air bypass valve on it? It may be stuck open.
Survivalist 2011-11-04 23:03:36
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.
Spdloader 2011-11-04 23:03:38
If it’s stuck, pulling the wires won’t change it, but that doesn’t mean it’s
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,
Survivalist 2011-11-04 23:03:48
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?
Bob 2011-11-04 23:03:55
If unplugging the IAC doesn’t change the idle you have 1 of 3 possible
1. Vacuum leak
2. Stuck IAC
3. Throttle stuck partly open or someone has improperly adjusted the
An easy way to see if you have a vacuum leak is to pull the rubber inlet
ducts off of the plenum and cover the intake with a clipboard while the
engine is running. If it dies immediately you don’t have a leak. If it wants
to keep running you should be able to hear a loud hiss coming from the
source of your leak.
Survivalist 2011-11-04 23:03:58
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.
Lugnut 2011-11-04 23:04:13
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.