E350 1995 5.8L fast idle

[tripan]

Changed IAC, and PCV (easy, cheap, made sense) van has 134,000mi+ couldn't hurt anyway. No luck, still fast idle, checked most vac hoses, all seems ok.
Bad new IAC ? Good parts can be hard to find these days.
Any ideas, anyone?

 

[blacksnapon]

Get some carb cleaner on a rag. Then on the inside of the throttle body, open the "butterfly" and clean the inner parts of the throttle body and the butterfly. Gum and varnish buildup can affect the airflow.

 

[BIGRED911]

my 92 5.8 sucked the intake gaskets in and caused realy high idle....only had a slightly dirty k and n airfilter..it stays clean now...

 

[5.0Flareside]

id say something like Vince said... probably just an airflow issue with your throttle body.. maybe some gunk stuck the throttle body open..

 

[tripan]

Will try your suggestions tonite, thanks for the input.
Will post outcome, really hoping it can be that simple, once in a while.

Thanks again...

 

[Tigeriron]

Fast Idle

Changed IAC, and PCV (easy, cheap, made sense) van has 134,000mi+ couldn't hurt anyway. No luck, still fast idle, checked most vac hoses, all seems ok.
Bad new IAC ? Good parts can be hard to find these days.
Any ideas, anyone?

I have a 1995 E350 with this same 5.8. I was plauged with intermittent hi-idle as well. I checked the usual & then settled on the TPS. As it turned out, I had some coolant leaking onto the TPS (Throttle Position Sensor) and indeed it finally shorted out. I suggest checking this & cleaning it first. If you notice any change, it is not too expensive to replace. I was lucky, as I had already isolated it just before failure, so I replaced it & all is well.

So, that would be my suggestion to you.

Good Luck!