I have a Bronco that I use on a ranch..It has a very high idle around 1700 runs great but I know something is up..I am going to replace the vacuum lines hopefully that's my culprit..But it needed a muffler awhile back and I had the guy take off the cat and install the new muffler it was about a year ago and I am wondering if that caused the high idle?

Thanks
Brettk1

 

#1 case of a high idle is a vacuum leak or leaks. Multiple common areas where vacuum lines break and reservoirs rust through.

Simple test: Start the truck, then remove the connector to the IAC. If the idle RPM drops down to 300-500 RPM or the engine dies, your issue is electronic. If the idle RPM remains high, you have a vacuum.

 

Thanks Rla2005 I Disconnected the IAC no change so vacuum prob.... When I disconnected the maps sensor hose the idle went down to 700rpms so does that mean map sensor is bad? The hose had plenty of suction can it have too much suction?
Thanks,
Brettk1

 

Was the IAC also disconnected when you got the idle RPM down to 700 RPM?

No

 

It's fixed!! Thanks again Rla2005..I took off and cleaned the IAC and the butterflies..Think that did it..But here are some observations..
The IAC was connected when I pulled the map sensor hose and it went from 700 to 1700rpm. IT was weird as you put the hose close it would rev like someone hit the throttle.
I also noticed the charcoal canister was missing a cap.. hopefully that was the strong gas smell we have been fighting..thought it was because it was burning so much gas from high idle...

Thanks, again,
Brettk1

 

Glad to see you got it fixed. Happy to help and thanks for the feedback!