'91 Ranger 3.0 High Idle..!

[snahman]

Hello..My 91 3.0 just started all of a sudden idling high..! It idles in park around 2000 rpms. I took off the IAC cleaned it,replaced and it actually idle down to normal. I then shut off the engine came back about 30 minutes later and it started idling high again! Thanks..!
BTW, with the truck running, I can unplug the IAC and it still continue to run at high idle.So this means vaccumn leak some where else? There is a leak coming from the brake booster hose grommet especially after you shut the engine down you can hear it and when you push around on the fitting going into the booster, it stops leaking! Could this be a contibuting even though the leak was there before I started getting the high idle and it ran normally..Thanks..!

 

[RonD]

Cold engine should idle at about 1,100rpm, computer is Choking cold engine until it warms up, high idle with Rich fuel mix
Then as it warms idle will start to drop down.

Yes, with IAC Valve unplug from power RPMs should drop to 500 or engine should stall either is correct, and means no vacuum leaks.

Could be PCV valve is dirty/bad, PCV valve should be closed at idle, very little air flow passed it, thats what the weight inside it is for.

 

[snahman]

Cold engine should idle at about 1,100rpm, computer is Choking cold engine until it warms up, high idle with Rich fuel mix
Then as it warms idle will start to drop down.

Yes, with IAC Valve unplug from power RPMs should drop to 500 or engine should stall either is correct, and means no vacuum leaks.

Could be PCV valve is dirty/bad, PCV valve should be closed at idle, very little air flow passed it, thats what the weight inside it is for.

Hello..Thanks for the reply.I put in a new PVC but I guess it could be not an optimum one....Advice on a better one..?