Hi all -- my 98 f150 (5.4, automatic) occasionally dies at low rpms. It runs fine if i keep it above 1000 rpms or so. If I can finaggle it into drive, it drives and sounds/feels fine at typical rpms. However, if i slow to a stop, it will die again.

Complicating the problem is that this problem seems to be intermittent: it started two days ago -- and out of the 4 times i have gotten into the truck, twice it has not occured.

I am nervous about taking it to the dealer when i am not sure the problem will reoccur, but definitely want to figure out what is causing it. Any ideas?

 

My 99 5.4 is doing something similar. Mine tends to run very poorly when cold. Idles about 450-550 rpms. Once the engine warms up it seems to go away. The problem is fairly consistent.

I suspect in my case it's the idle air control motor. I think it might be anyway. I have 113K on mine.

 

both times it had problems were in the morning (first time to get started that day).

Given that the ford dealer wants $140 just to plug it in to a computer, i think i will try to deal with it or find another place to take it.

 

I plan on getting that IAC motor tonight and plugging it in. If it works, I'll let you know.

I went to Autozone, and I swear everytime I'm there I leave with the feeling the people I talked to can't identify anything beyond oil filters and brake pads.

 

I went by a dealer to pick up the IAC valve. $73, + $1 more for a new gasket.

The valve is located on the intake, behind the throttle body. It's held in place with two 8mm bolts. They're pointed away from you, toward the passenger seat. It's pretty close to the firewall, so I found a gear wrench worked best. It helps if you're ambidextrous. Even better if you're left handed.

I noticed a difference between the old and the new. There is an exposed spring in the old, that had a lot of crud (carbon) built up on it. Makes me think they did a little redesigning.

Either way, it's a long reach over the engine. I'm glad the engine was cold.

I had disconnected the negative battery cable to do the job, I didn't know if there would be a code to clear, so I figured it wouldn't hurt.

The difference is remarkable. This morning it started as rough as a cob. So bad in fact I parked it and drove another car to work. When I started it just now it was smooth as butter.

I hope yours gets cured as easily as mine turned out.

 

They can't. I once asked for a water pump for a Corvair and they said although they didn't have one in stock, they could get me one in a couple of days.

 

Water pump for a Corvair,,,,,,,WEEEEEEE,,,,,,,almost as good as asking for a fan belt buckle, a brake shoe lace, or the ever popular finnegan pin on the muffler bearing. I wonder when they will get those in stock??? LOL

 

I had the same problem once, a new IAC fixed the problem. It's weird how intermitent it can be though.

 

did yall try just raising your idle it seemes like if your car idle higher you would be dieing like that... or is that jus tthe redneck way of avoiding the problem and not fixing it

 

I'm not sure the IAC is adjustable. I believe it's all up to the computer.

 

im not sure if you can do it on late models but i know you can on older ones. I have done it to my friends 72" fj-40 land cruiser and as far as i knew its a little trickier with newer models but it was possible

 

I am not to sure, but I highly recomend to check at the posibility of having an exhaust gas recirculating valve locked at open position. When this occurs exhaust gases get in the intake during idle and create poor idle performance.