Idles at 5000rpm

[IOWNJUNK]

I checked for vac leaks, one small leak at the pcv, not enough to support 5000rpm. I even stuffed a shop towel into the throttle body to block it off and there was no change.

 

[IOWNJUNK]

It could be the IAC valve being faulty? Do you still have the old one?

Does it with both. Plunger actuates on both

 

[IOWNJUNK]

To get to 5,000 rpm is far more airflow than the IAC or a vacuum hose can move. The throttle is either hung open or the plenum exploded and cracked. Also could have had one of the rubber orings that seal the spider or plenum give out.

It's a big hole with a lot of air so it should be obvious. I don't see anything cracked or broken. Never thought of the Owings where the spider assembly sits. That will be my next check, thanks.

 

[Caman96]

I’m surprised you didn’t hear the old “is the floor mat stuck on pedal”?

 

[IOWNJUNK]

Gave it another look. Stuck my hand behind the manifold and the entire gasket has been blown out from between the upper and lower intake manifold. Easy fix, just took a week to find the problem. Thanks for all the help guys.

 

[BuiltToWork]

Thanks for the final reply with the resolution!

 

[351FUN]

Thanks for the final reply with the resolution!

Right? I love seeing an answer, I hate when there's a mystery and the OP never comes back to answer it. Hell I'm guilty of it, I solved my mystery engine problems with a new engine so I never got a solution.