1994 F150 - irratic idle problem

i have a 1994 F150 pickup and it just started having an idling problem. how do i get the error codes from my truck? what do you think it might be?

thanks

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i have a 1994 F150 pickup and it just started having an idling problem. how do i get the error codes from my truck? what do you think it might be? thanks

Scott,

Which engine do you have?

The erratic idling -- does it surge at random intervals or is it just idling poorly?

I would recommend picking up a Haynes manual from your local auto parts store (Napa, AutoZone, etc). They'll have a manual there for 80-96 or 87-96 F-series and in it they'll document how to pull codes from your computer.

It's been a few years since I've done it (when I had a '91 Bronco), but it basically consists of finding the testing relay in the engine compartment (on the driver's side fender), jumping two of the connectors with a short wire, turning the key to the "on" position, and counting the number of times your "Check Engine" light goes on. Something along those lines...it's really simple.

The Haynes manual also outlines common error codes which you can compare your results to.

Good luck.

I had the same questions first, what engine do you have and what exactly is the idle prob. I have had a prob with the throttle pos. sens. causing some really crazy things. Also check the vacum lines that run around the back of the intake. They are the multi-colored set of about 4 or 5 plastic lines. They have a habbit of breaking and causing vacum leaks.
Steve, NE

Hey I too am interested in this problem because my truck all of a sudden started to Idle rough and it shakes my truck. As you get to 35mph it quite but acts like the brakes are being mashed to the floor.I went to work this morning and cut it off and when i restarted it at dinnettime it begans its problem. I talked to my uncle who is a mechanic and is supposed to take a look at it tommorrow, but he said it sounds like the mapping sensor went bad. I myself have no clue, and if anyone has a definate answer please let me know.

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Hey I too am interested in this problem because my truck all of a sudden started to Idle rough and it shakes my truck. As you get to 35mph it quite but acts like the brakes are being mashed to the floor.I went to work this morning and cut it off and when i restarted it at dinnettime it begans its problem. I talked to my uncle who is a mechanic and is supposed to take a look at it tommorrow, but he said it sounds like the mapping sensor went bad. I myself have no clue, and if anyone has a definate answer please let me know.

Hi Jason, Sounds like your brake booster is bad or the vacuum line from your intake to the booster is leaking.

As far as leaks go, the best way I found to find them is to use a non-flameable (stuff) in a can, that you would spray in one area at a time until you hear the motor raise in speed and then go back down (this is the area of the leak), Then you need to find it.

Please Note : You can find a vacuum leak very quick this way (use a Non-Flamable Product though) not your sisters hair spray, Long story.

Hope this helps.

Pulling codes on a pre 96 ford is a pain. AutoZone will do it for free. Idle problems on a Ford are usually caused by the "throtle air bypass valve "(ford speak)or Idle air controle valve ( what every one else calls it ) but it could be a vacume leak or bad/leake egr valve, also what condition are the spark plugs wires etc. and it could be that you need to put some good injector cleaner in (pay atleast $5 or more for a bottle, that cheap stuff is a waste of money. STP in a silver bottle is good $7 ).