Idle problems
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New User
Joined: Aug 1999
Posts: 8
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Idle problems
1990 F250 4x4 460 , 3 spd auto,air, cruise. Seems to idle a little slower than usual..5-600,But when put in R or D, the idle jumps up strongly to about 700 and the truck tries to take off suddenly. when shifting back to P or N, it drops off dramatically, and sometimes will die before evening out. The difference is still there with the AC on, but not quite as noticeable.Any ideas? Thank you very much.
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Joined: Jun 1999
Posts: 1,525
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Idle problems
I think the problem is a vacuum leak.The computer will try to maintain idle according to load on engine,making erratic adjustments when you drop it in gear and out of gear.Startt by checking the vacuum line at the trans. modulator.Then all the ones in the engine bay including the PCV valve.Refer to the emissions decal for vacuum diagram.
Phillip
Phillip
