High Idle??
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New User
Joined: Sep 2006
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High Idle??
I have a 1996 F-150 4WD with a 302 and a 5-speed manual when I start it the idle is around 2500 rpm it does'nt go to a low idle, also when driving and I go to change gears the rpm's will go from 1500 to 2500, it takes a while for them to go back to normal, it will seem fine until I change gears and it will shoot back up to around 2500 rpm. Also the check engine light isn't on!!! Any Ideas? This is a great site and I find that all of the posts are very helpful
Elder User
Joined: May 2006
Posts: 623
Likes: 1
From: Mississauga,Ont.,Canada
Check throttle plate and linkage to make sure it is closing properly. A soaking of wd-40 around the return spring and pivot points has worked for me in the past. A vacuum leak can cause this also. Look at the vacuum hoses and check for cracks and splits or one that has come off.
Tuned
Joined: Jun 2006
Posts: 420
Likes: 4
i had the same thing with my 90 f150 5L 5 speed. i was throwing a 42 code mostly, and a 41 code now and again. i took out my o2 sensor and i could hear something rattle inside of it. sure enouf it was so bad that the porcelin had cracked and was beyond shot. i just put a new o2 sensor in and sure enouf it seems to have fixed the high idle problem. i haven't drivin it long enouf to say forsure that the problem is fixed, but it might be something to look at.
Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
posted this in another thread:
To save yourself some expense, pull the code first!!!
Then very carefully check every vacuum line running any where in the engine bay. Replace any faulty or suspected of being fualty hoses. Hard hoses should be replaced because they can crack and leak as well. If you do not have a multi meter, obtain one. Then go to fordfuelinjection.com and start testing all your sensors per their suggested method. Replace out of range sensors as necessary. If it is still running fast, clean the throttle body and the idle motor to make sure that it is not holding open. Also, use a hand vacuum pump to check your vacuum switches, and the canister purge valve. A small amount of leaking is factory excepted, large amouts, i.e. fast vaccum drops, is not acceptable. Still High idle? shoot it.
Then very carefully check every vacuum line running any where in the engine bay. Replace any faulty or suspected of being fualty hoses. Hard hoses should be replaced because they can crack and leak as well. If you do not have a multi meter, obtain one. Then go to fordfuelinjection.com and start testing all your sensors per their suggested method. Replace out of range sensors as necessary. If it is still running fast, clean the throttle body and the idle motor to make sure that it is not holding open. Also, use a hand vacuum pump to check your vacuum switches, and the canister purge valve. A small amount of leaking is factory excepted, large amouts, i.e. fast vaccum drops, is not acceptable. Still High idle? shoot it.
Posting Guru
Joined: Nov 2005
Posts: 2,442
Likes: 1
From: La Grande, OR
another thing that may be causing you problems is your Idle Air Control (IAC) valve on your throttle body, or the TPS sensor at the bottom. I have had this problem, along with countless others, and these two seem to be the biggest problems. you can take off the IAC, or the whole throttle body, soak it all in some carb/throttle body cleaner, and blow it out and let it dry. This might solve your problem, but the vacuum hoses are also a big one to look out for.
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