high idle
Thread Starter
|
New User
Joined: Nov 2008
Posts: 16
Likes: 0
at the same time i changed the tps and cleaned the TB i also replaced the pcv valve. i have adjusted the tps several times and i have gotten it to idle a little lower but is still too high. at first startup it will run at roughly 1300 rpms then after a little while it will drop down to 1000-900rpms. i have also significantly lost fuel mileage. haven't been able to find any vacuum leaks so far either. any suggestions?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Use a hand held vacuum pump/gauge to test each vacuum circuit/component. My '92 F350 passed all the spray carb. cleaner on the hoses/intakes tests I could throw at it but it still idled similar to yours. Once I used the vacuum pump/gauge I found numerous hoses were faulty as well as a rusted through metal vacuum reservoir.
Post Fiend
Joined: Oct 2003
Posts: 6,214
Likes: 13
From: New Jersey
Sounds to me like a vacuum leak. The vacuum lines age to a brittle state and when disturbed by working on the engine you can easily fracture them.
If that checks out okay (with a gauge as others have suggested), then I would check the IAC valve that's mounted on the intake. Sometimes they get clogged up or "stick".
If you're lucky like me, you're truck will eat one every 40-50,000 miles.
If that checks out okay (with a gauge as others have suggested), then I would check the IAC valve that's mounted on the intake. Sometimes they get clogged up or "stick".
If you're lucky like me, you're truck will eat one every 40-50,000 miles.
Thread Starter
|
New User
Joined: Nov 2008
Posts: 16
Likes: 0
thanks for the suggestions. i will check out the vacuum lines in the next few days. hopefully this cold weather will get out of here. and the iac appears to be new. the previous owner must have changed it not long before i got it. it looks brand new and i cleaned it out when i had the TB off. if i unplug the iac the rpms do change so apparently it is working
Thread Starter
|
New User
Joined: Nov 2008
Posts: 16
Likes: 0
i checked all of the vacuum lines that i could get to as well as the vacuum can and all checked out fine. tps is set to 0.940V at closed throttle and still fighting the high idle
Trending Topics
Junior User
Joined: Jul 2008
Posts: 58
Likes: 1
From: Prince George, BC
Did you remove the TB butterflies? When I gave my TB a really good scrub down I didn't get them in properly and it had a higher idle. Not sure how much, as I lack a tach.
Loosening both valves off and playing with the throttle arm got them centered and I torqued them down again.
Loosening both valves off and playing with the throttle arm got them centered and I torqued them down again.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Post Fiend
Joined: Sep 2009
Posts: 23,620
Likes: 2
From: Coeur d alene, Id
is there a spring on your tps? when i replaced the one on my xterra i happened to not upt it in exactly right and it idled high.. I adjusted it and it ran fine after that. just a thought
Post Fiend
Joined: Sep 2009
Posts: 23,620
Likes: 2
From: Coeur d alene, Id
yes the one on the inside.. i had put the little nub ( i have no idea what to call it) on the wrong side of the linkage in my xterra.. i reversed it and now it runs great...sorry for the vagueness..lol