4.2 high idle speed.
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Member
Joined: Mar 2000
Posts: 29
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From: San Antonio, TX
4.2 high idle speed.
1999 4.2, 5 speed, about 52k miles.
Once in a while, but more frequently this past month the idle speed will jump up to anywhere from 1400 rpm to say 2300 rpm. This is in neutral with clutch engaged or disengaged.
It doesn't happen all the time, but just occasionally. There is no MIL (check engine light ever). Most times it will come back to approximately 825 rpm after the "episode", but sometimes it will stay at the high speed till the engine is shut off. Sporadic behavior at best. The actual speed of the "high idle" changes from episode to episode.
Sometimes I can feel it in slow traffic when in 1st or 2nd gear -- brakes need to be applied to keep the truck from "running away."
Any ideas? Anyone else experience this out of a 4.2?
Once in a while, but more frequently this past month the idle speed will jump up to anywhere from 1400 rpm to say 2300 rpm. This is in neutral with clutch engaged or disengaged.
It doesn't happen all the time, but just occasionally. There is no MIL (check engine light ever). Most times it will come back to approximately 825 rpm after the "episode", but sometimes it will stay at the high speed till the engine is shut off. Sporadic behavior at best. The actual speed of the "high idle" changes from episode to episode.
Sometimes I can feel it in slow traffic when in 1st or 2nd gear -- brakes need to be applied to keep the truck from "running away."
Any ideas? Anyone else experience this out of a 4.2?
Member
Joined: Feb 2002
Posts: 26
Likes: 0
From: Woodbridge
I had the exact same problem, looked for vacuum hoses leaking, and other things. Even got a computer reader, I could find nothing. This went on for a week. I unhooked the battery cable to reset the computer and left it off over night. I have not had a problem since. Its been about 8 months. Good Luck