I have a 91 F150 302 EFI, 5 speed. This has been going on for awhile now and usually when it is cold out and the engine is just warming up but its been more common now. When I push the clutch in to shift gears the engine revs up and makes for a crappy shift. what is the problem, trottle stick? How can this be solved? is it something electronic?
Thanks

 

Does it rev up higher in rpm's, or just hang. I think it may be the rich condition the engine runs in until it goes to closed loop (regular running) mode. If you let your truck sit and go through its high-idle and then go to regular idle on your own THEN start out, does it continue to do this? Does it do this after a minute or two after the fast idle stops?

I know my 302 is cranky if it doesn't get fully warmed up, and hangs hte rpm's out for several seconds before dropping so I can engage gears properly. My 300 does the same thing. Both 5-speeds.

Like I said, I think its because of hte rich condition. The engine is dumping extra fuel in, and then all the sudden the load of the transmission (and everything behind it is removed, allowing that fuel to bump the rpm's up or at least hold them until its emptied out a bit.

Edit: If you don't let your truck warm up through the higher idle...you may be doing damage to your engine. That high-idle is important to build up oil pressure fully, and for the oil in the engine to be warmed above a syrup consitency. I hate waiting for it to warm up..but I try to at least allow my engine to go through the idle sequence and then idle a bit more just to ensure that my investment (expensive...) is properly lubricated before driving off.

 

The engine will rev up not hang when the clutch is pushed in. It has happened though after the truck has been fully warmed up. I usually always wait atleast until the rpms drop from the intital starting rev (I beleive what you call the high-idle stage) when first start the truck . So could there be anything that could be replaced if it is not something normal. Like some sensor? Also if I tap the gas pedal the rev will go back down. And the rev will eventually drop down, lets say if I push in the clutch when coming to a stop. Also some had mentioned in other post to try and replace the IAC sensor. What do you think? Thanks
And to throw this in there; when I go on long trips lets say doing 65-75mph for about 4 hours the checkengine light will come on and then once off the highway (driving alot slower) for a few minutes the light comes off or if i turn off my truck and start it again. I have notice when this does happen, off the highway driving can be some what hesitant and choppy, but my truck's pedal and trottle seems to be hesitant.

 

Go to autozone and get codes read. Sounds like there might be some computer trickery going on here. Or check them yourself...you can find a computer codes site easily. I'll try ot look it back up in a bit.