Idle erradic
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New User
Joined: Oct 2010
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Idle erradic
1989 F150 5.o fi.
I replaced the throttle cable and it will still idle at 1500 rpms or more. Doesn't do it all the time but enough. Even when the engine is at operating temp it will idle at high rpms.
I did a search so is TB cleaner, the IAC valve and a error code my options?
I replaced the throttle cable and it will still idle at 1500 rpms or more. Doesn't do it all the time but enough. Even when the engine is at operating temp it will idle at high rpms.
I did a search so is TB cleaner, the IAC valve and a error code my options?
Posting Guru
Joined: Jun 2003
Posts: 2,314
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From: southwest michigan
Starting with error codes is always a good way to prevent wasting money on parts. Have you concidered verifying that the TB is closing all the way. If it is, the air must be getting in another way, which would lead me to either a leak somewhere or the IAC valve.
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
Check ALL vacuum lines. Look for any sings of brittleness or cracks. IF there is a crack, chances are there is air being sucked in.
Also check the operation of the IAC. A good way to test it would be to disconnect it. IF you do and the idle doesn't change, chances are it's the culprit. Even if it doesn't do it, I would still remove it and clean it with carb or electronics cleaner. Look to see if the plunger can move freely inside the assembly. It may be carboned up and not allowing the plunger to work correctly. When removing, be careful not to damage the gasket that's between it and the throttle-body. I don't know of to many parts stores that are open on the weekend and none that stock the little gasket on hand. It will be a day to get it from them or a dealer. Bad thing is though, the gasket is 21 years old and may be in need of being replaced as well.
Also check the operation of the IAC. A good way to test it would be to disconnect it. IF you do and the idle doesn't change, chances are it's the culprit. Even if it doesn't do it, I would still remove it and clean it with carb or electronics cleaner. Look to see if the plunger can move freely inside the assembly. It may be carboned up and not allowing the plunger to work correctly. When removing, be careful not to damage the gasket that's between it and the throttle-body. I don't know of to many parts stores that are open on the weekend and none that stock the little gasket on hand. It will be a day to get it from them or a dealer. Bad thing is though, the gasket is 21 years old and may be in need of being replaced as well.
