Hello all you fellow F-150 owners, heres my delima. I have a 1997 4.2 V6 F-150 with 170,000 miles. Right now it will not idle at all, but IF (not often) dose it will idle at aroudn 400 RPMs which is very bumpy. Also it will just shut off on me at times like driving down the highway. Sometimes it will start back up, sometimes I have to wait a little while. Any ideas? Heres the engines history:

Addons: K&N air filter and Flowmaster muffler

Maintenance:
I JUST put in a new computer thinking that was it, but no, also cleaned the MAF sensor with rubbing alcohol.
At 130,000 miles it bent a connecting rod. fixed it, bored the cylinders, new piston rings, cleaned EVERYTHING!!
At 150,000 miles new IMRC valuves (both)

Also, about the IMRC valuves. My check engine light was on saying the one on Bank 2 was stuck open. The dude at the ford place said its the one on the passenger side, so I bought a new on and put it one. Light came on for the same code, so i relaced the one on the driver side, no luck, light still came on. It is still on to this day also. Is there any connection? I have had that problem for years but the truck has never just shut off on me before. If no connected, how is it fixed?

THANKS A LOT GUYS!!

 

Have you tried cleaning or replacing the IAC valve? They do get carboned up pretty bad.How about the throttle body; ever clean it? Fuel filter been replaced lately,or ever? Try unplugging the MAF sensor; if it runs better then your MAF sensor is bad.Thats how I found out mine was bad.

 

Yep, if you're having an idle problem, the first thing to check is the IAC valve.

The IMRC valves shouldn't affect the idle. If you've changed them both, then I'd check the plastic vacuum tube that controls them.

 

would the IAC be the reason for the engine just shutting off while on the road? I will look at it in the morning. Yes, it probably is time to change the fuel filter and get some of that Ford Safe Throttle Body cleaner. I will also run the engine with the MAF sensor unplugged to see if that will help or not. Im over in Seffner all the time Blue Oval!

 

Any throttle body cleaner will do.Just dont use carburetor cleaner!!!!!!
Seffner is a small town; you have friends here?

 

First thing I did was unplug the MAF Sensor, it turned over twice, didnt get over 500 RPMs and shutdown within 2 seconds. After that it would not turn over, even when I plugged the sensor back in, maybe I need to unplug the battery to reset the computer. I took off the IAC valuve and its kinda dirty in there, i dunno about cooroded, is there suppose to be oil or something in there? I use to live in Valrico, moved out a year ago, still go down there cause I go to the Lightning games and my rents are still there. What about O2 sensor? Cause its not just the idle, it just shuts off goin down the road at like 2500 RPMs or something

 

I cleaned the IAC and the Throttle Body, now it will not start. I will leave the neg cable off the battery over night to try to reset the computer. The dude at discount suggested a Crankshaft Sensor. I bought one of those and a fuel filter, the crankshaft sensor will not be in till tomorrow, so I will install both then.

 

If you're just going to start replacing random parts, take it to a shop and have them fix or diagnose it, and then you can replace the correct part. It'll get awfully expensive throwing parts at it. Just a thought....

 

not throwing random parts on, just the ones thats are suggested, not like im getting a new tire or something

Will probably pitch that to my parent. I am lucky enought to where they are paying for the parts for this considering this was wrong since they gave it to me, Im tried of working on it and it still not running! lol

 

What About Fuel Filter