Okay... Here's the story. I've been driving my '99 F-150 since the day I bought it and haven't had a single problem during that time. I'm at 84K miles and beginning to have problems getting it to start for the first time on any given day. Am I due for a spark plug change? I pulled #1 lst weekend and it looked to me like it was about time. I fear the worst since cold weather isn't too far off. (Cold is relative, since I'm reporting from Houston)

I just want to know where to direct my attention for the best results

 

It sounds to me like it is more than likely the IAC starting to go. Does it start and then shut off right away? Does it help if you give it a little gas after it turns over?

 

I to have a 99 that I bought new and it is at about 85k.

My IAC acted up last month. be more specific when you say you had trouble starting it.

My starter solenoid went bad at about the same time my IAC went.

 

My wife's work van started having cold start problems about 15000 miles after new plugs were installed. I thought it could not possibly be them, but... I did not change them, the local Ford dealer did. Tried everything to no avail, finally as a last resort I began pulling plugs(this is a full size van with a V10, but that shouldn't matter) All the plugs were 10 to 15 thou too much gap, therefore once they were replaced with the proper gap, viola, no more starting problem. I still have a miss under load, but I think I have one or two coils puking out, I'm gonna have to get them checked. Sounds like your problem is similar to mine so hopefully this helps you out. I wish we could trust these dealers, but man they really let me down because not only were the plugs gapped wrong, but they put the air intake assembly back together without tightening it up and one section was partially off the throttle body letting all manner of crap in, buggers!!!!

 

So what is the IAC?

 

IAC (idle air control) valve

 

If you have to crank it over for what seems like forever after its been sitting overnight or whatever, I'm still willing to bet its your plugs, especially if it still won't start after you tip in the throttle. Those platinum plugs are "supposed" to be good for 100k miles and at 84k, you are getting close

 

Will a IAC problem generate any alarm codes or "engine service" light? The engine will fire almost immediately but will not continue to run, unless I try to give it more gas. After the engine warms up, it will run fine.

Back in the pre-electronic days, that kind of problem would be because of bad plugs or points or carberator adjustents or, or, or...

Thanks everone.

 

Definitely sounds like IAC. Take the IAC valve off the throttle body and clean it really well.

 

An IAC problem will rarely throw codes. If a code is thrown usually something else has thrown the code, the IAC may be related to the problem.


There is no sensor connected to the IAC

 

I am continuing to monitor the situation on my truck. Today I was trying to go to the store (first time this day to start the truck), and when I started it, again it would almost immediately die unless I would try to add gas. It required both feet to work the accel. and brake simultaneously to limp out of the driveway and try to get around the block, hoping that after some warm up, things might start acting right.

Things didn't really improve until about 10 min. later as I was pulling up to a traffic light. All of a sudden, the engine raced and and if I hadn't been on the brake, would have plowed into the car in front of me. After that, the engine ran fine.

To me this would indicate that it is the IAC that is acting up, thanks to earlier responses of this situation. THE QUESTION: Is the IAC module servicable?.... can it be cleaned or should it be replaced? The info. from my Chilton's manual says it cannot be cleaned, that there are electronics etc. inside. The manual says to check resistance across the terminals. I'm sure that as soon as the engine started running properly the resistance values would be within range, but before "engine race" maybe the values were wacked out.

OTHER QUESTION: Is the IAC a "FORD Only item" or something that can be bought at the local parts house, or should it be treated as a "FORD only item"?

Your experience and opinions are appreciated.

 

The IAC isn't meant to be serviced, but some folks have cleaned them with a bit of carb cleaner and got decent results. I don't know whether AutoPepBoysAdvanceZone carries them, I've never tried buying one from them.

Not so scientific IAC test: Next time your truck dies after start up, lightly tap the IAC with a screwdriver or something and try it again.

 

again my 99 was doing the exact same thing your is. I did the IAC test with the screw driver handle and low and behold it fixed it.

So I removed the PIA IAC (It's very awkward to get to on a 5.4) and cleaned it with intake cleaner and brake klean. (Do not ever use carb cleaner on any part of these trucks) So far it is running fine. When it acts up again I will replace the IAC.

 

IAC vavles are no more than 5 bucks (I bought one for about 2.50) at Auto Zone... and they take less than a minute to replace. I think that cleaner would be more expensive and troublesome than replacing it. Give it a try and see if that fixes it. There are some good pictures in other posts on here... search for "IAC Valve" (with quotes) and you will see some good stuff.

 

Sorry JohnnyB you are sadly mistaken. I believe what you think you are talking about is a PCV valve which is about $2.50 and takes less than a minute to replace.

An IAC on the other hand (On the 5.4) is in an awkward place up against the fire wall and they cost over $40.00

http://www1.autozone.com/servlet/UiB...+CONTROL+VALVE

So yes it is worth a try to clean it first.