Hey guys,

I've had an intermittant problem for a long time in '93 F-150. When put into reverse (after warming up) it will often die if not given a good deal of throttle. Also, occasionally the rpm will drop to 500 or lope when it is warm and idling at, say, a stoplight. Dad seems to think it is the computer and there is nothing wrong with the motor or transmission since the problem almost always disappears when the engine is cut off and started up again. Do you think it's the MAP sensor? What are the usual symptoms of a bad MAP sensor? And how much cost, time, and labor would it be to replace one? Thanks

Jordan Z

 

its mostly a cost thing last i checked they were about 95 bucks but otherwise its a matter of unbolting it undoin the pigtail and vacum line. it is right above the plenium on the firewall . also check for any other vac leaks and i dont know but i screwed that screw in on top of the plenium to open the throttle a bit more and it helped mine b/c it would kill if i turned the wheel in park but this is pure ly a speculation, and probaly not a fix

 

Thanks for the input! That's not too bad of a price, especially to fix this stupid problem

 

That's not the problem.
A bad MAP will cause it to not run. When you start it up you will have to keep feathering the gas just to keep it running whether it's cold or not.

I would pull the IAC (Idle Air Control valve) off and clean it. They can get plugged up and cause a bad idle and other similar problems.

Just take it off (it's mounted on the side of the Throttle Body), (click HERE for instructions) and take the two screws that hold the valve on and clean it out with carb cleaner.

Pull the codes, you may just have a sensor out, like the O2. Click HERE to learn how without a scanner, I use a jumper wire and a test light. Buy a Haynes manual, these are the best for diagnosing computer related problems. Don't buy any sensor's until you have tested them, this method can and will get expensive.

Post what you find.
Good luck!

 

Well it can't be the IAC because I changed that about 6k miles ago, along with plugs, wires, cap, and rotor. I guess I should get up off my butt and pull the codes, huh?

 

Yeah, I would pull the codes. It could still be the IAC, It's not necessarily bad but it could be dirty. It doesn't take much to make the valve stick.

 

I have a 1995 F150 5.8liter and I cannot find the MAP sensor. I have no problem finding the MAF sensor but the other i cannot find.
Please advise
Ken

 

Since your truck has a MAF sensor there is no MAP sensor.

If you are trying to resolve an issue it is best to start your own thread.

 

Did anyone on this thread know and remember there is a gasket that comes with IAC valve. If you didn't get the gasket when you bought the IAC valve I suggest going and getting it. That's your problem. I've got A 1995 f150 2wd 302 5.0 and replaced IAC valve. Started spitting and sputtering after bout 1000 miles. I'd also change your upstream 02 sensor as well.