Idle Gets way hung up! HELP!!!
Thread Starter
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Senior User
Joined: Feb 2005
Posts: 200
Likes: 1
From: Chester County PA
Idle Gets way hung up! HELP!!!
I have a 91 f150 5.0 5speed manual tranny. The problem is that it idles way too high most of the time and in between shifts. For some reason the computer seems to be telling the IAC Valve to stick open or stay there for awhile. When I go to shift and push in the cluch once disengaged the engine revs up to 2500 or 3000. Its a relly annoying problem. Its not the IAC because I put a new one in, And it also isnt the idle adjustment screw.
Also... It dosent relly do it on warmup cycle, Only after its warmed up.
Please help!!!
Also... It dosent relly do it on warmup cycle, Only after its warmed up.
Please help!!!
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
Maybe you have a vacuum leak? I'd also suggest pulling the codes. Do it yourself with a paperclip. The directions are on www.fordfuelinjection.com
Thread Starter
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Senior User
Joined: Feb 2005
Posts: 200
Likes: 1
From: Chester County PA
the tb iss clean. The truck did it when the engine blew (#8 piston cracked). I had a new motor put in and it still does it. All the components are clean. When I pulled the codes with the old motor, i cant remember the number that came up but it saw something about a (open circiut or SAW) . All the vaccum lines are good. I'll pull the codes with the reader when I get home. Think it could be the Distributor control module malfunctioning. I tried putting a different computer in and it did the same thing.
New User
Joined: Apr 2006
Posts: 5
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I have a '92 F-250 5.8 and I am having a VERY similar problem, I also was told to try the IAC Valve and am hopeing to get a chance tonight. But I like yourself am at a loss. Someone help us...
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New User
Joined: Apr 2006
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I have a 1993 F-150 5.0 manual transmission and am also having an almost identical problem. Many repairs but no fix.
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Elder User
Joined: Mar 2004
Posts: 500
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From: Penndel, PA
Had this exact problem for a while...no codes, no vacuum lieaks couldn't figure it out for the life of me. Try this...when this idling condition exists, pop the hood and try to physically close the throttle body by hand. If the condition stops, chances are the return springs for the TB are shot. I stuck an old carburetor return spring on there and haven't had the problem since. The gas pedal is a little bit harder to push though. Give it a try, can't hurt.
Senior User
Joined: Jul 2005
Posts: 128
Likes: 0
From: Otsego, MN
I have same problem as well, but does not go above 1200 rpm, then quick hit the pedal and goes down. My engine as well blew #8 piston @114,000 miles. I cleaned the TB and put new return spring on and helped as well. I still have a EGR stuttering problem that I think fried the old engine, I think. 5.0L/5spd.man. also. Good luck.
Thread Starter
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Senior User
Joined: Feb 2005
Posts: 200
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From: Chester County PA
I pulled the codes today and got nothing except a (power steering pressure code). I cleaned the TB and put a return spring on and it didnt help any. Im still at a loss. I then pulled the wire going to the IAC and it juns soo much better. This isnt a fix but it does tell me that something is telling the IAC to open and stay there sometimes. Im going to put a Ford Motor Sports MAF Conversion kit on soon anyway. Mabe that will help fix the problem. Anybody elese think so or know of good results from a FMS MAF conversion? Thanks
Senior User
Joined: Mar 2005
Posts: 341
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From: Newark
I have a '96 5.0 and have very simalar issues. Mine already has MAF. Still haven't figured it out yet. It seems to be an all too common problem on these trucks that no one ever figures out. I am just waiting for it to get worse then maybe it can be diagnosed.