I have a '98 F-150 and it hadn't been giving me any troubles at all until yesterday. It has about 110,000 miles on it. I went to start it and it would start but immediately die. I've never had to give it gas to get it to start but thought since it was a little bit cool outside that maybe it was just being stubborn. I gave it some gas and started it again. I kept applying the gas to keep it at a little over 1000 rpm's. As soon as I would let off of the gas it would die again. I then started it again and kept it running in the same manner until the temp guage showed the engine had warmed some. (Probably about 5 minutes) As soon as I let off the gas the same result. It dies immediately. It doesn't studder or anything. It just shuts off as if I had turned off the key. Any ideas? I really need help here. Thanks in advance for any help anyone can give.

 

i have 2 guesses for you that are often over looked.

make sure your coolant is full because when you first start the coolant temp sensor is tell the pcm what to do. if the coolant level is fine it could be a bad coolant temp sensor.

you might also want to clean the air temp sensor (and the MAF while your in there)

good luck.

 

You really think it could be something with temp? I mean I let it warm up by keeping the gas pressed and keeping the rpm's at about 1000 until it warmed up and it still wouldn't idle. It's raining here today so I don't know if I'll get to work on it today since I don't have somewhere to put it inside and work on it. Anyone have any more ideas that I could check if these don't work out while I'm under the hood?

 

I don't have an answer for you but my truck is doing the same thing...fires up and then stalls out unless I manually rev the engine. I've been searching previous posts and there seems to be lots of talks related to the IAC (idle air control valve) sticking or going bad. Look for a post labeled 'IAC went bad' there are some good pics of what the thing looks like.
Hope this helps out (for the both of us.)

 

I would bet IAC valve, I just replaced mine about 3 months ago. It did exactly what you said, it would start and if you did not hold the gas pedal at partial throttle it would die. If you tap on it when it does this, it will sometimes unstick, but eventually I couldn't unstick mine. Some people here have cleaned them with throttle body cleaner or brake cleaner, but sometimes that doesn't work or causes other problems. I bought a new one for about $80 at a dealership and installed it in about 5 minutes.

 

I would say the IAC is your trouble. My Expedition does the same thing when it is COLD outside. If I park the truck in the garage it doesn't do it, but if it is outside while it is cold it does it every once and while. I plan on cleaning my soon.
Good Luck

 

It is the IAC. You can remove it and clean it. Just use carb cleaner. Try not to let the cleaner run into the motor. Re-install.

 

I got a 2001 5.4 and it is doing the same thing. With 20,000 miles.

 

Thanks a bunch guys. I was reading in my Chiltons and it said that if you ohm it out you should get something like 8-12 ohms or something like that well, I got 9 ohms but I guess that only tells me that the electronics are ok not the mechanical portion of the valve. I think I may try cleaning it and see what happens. If it doesn't work I was going to have to buy a new one anyway. Who has had good luck cleaning theirs? I mean if it's only going to go another 5 or 10 thousand miles then I'll just buy a new one.

 

Just buy a new one. I cleaned mine somewhere in the late 40K's and by very early 50K's it was shot again. A new IAC is only about $45 from fordpartsonline.com or around $65 at dealerships.

 

Man, I can't wait until my next day off so I can get this thing fixed or at least work on it. I hate being without my truck. I'm driving a minivan and it's killing me. Well, I priced a new IAC at my local part store and it's $44.95 so not too bad. Only thing is I'm going to hate having paid that if it doesn't fix it. I don't want to pay the Ford house to do a diagnostic on my truck but that may be what I have to do. That will cost me 60 bucks and then I already know as soon as I pay them for it, they are going to tell me it's the IAC. I can't win on this one. I know one thing it sure seems like this is a pretty common problem though.

 

this may sound some what primative, but take a small ball point hammer and tap your IAC firmly on the metal housing, but don't get carried away, while somebody is cranking the engine over (you may not have to have anyone crank it over, but usually works better). This will ALMOST always cause it to quit sticking and provide a TEMPORARY fix till you can get a new one. You'll also have the piece of mind knowing it is in fact your problem.

 

Would this also be the cause of cutting out or hesitating while running? I don't have the problems at starting as described, my problem is when I am running, could be any speed, the engine or transmission, not sure which, will falter, hesitate, or cut out. Anyone had similar problems. I've got just over 49,000 miles on my 99 F-150 Supercab. Thanks!

 

Same problem with mine. Bought the IAC valve replaced it in about five minutes and problem solved.

 

02RegularCab4x4,

Thanks so much. I finally have some piece of mind. I went out and had my wife crank the truck while I tapped on the IAC. It started immediately and idled without issue. I'm going to the auto parts store in the morning. They already have one waiting on me. My wife said it wasn't the tapping on the IAC that worked though. She says it was her magic touch. She told me that she was just smart enough to start it and I wasn't. Oh well, I'll let her think that all she wants I guess since all I care about is my truck is running again.

Thanks so much for all y'alls help. I really really appreciate it.