Ok, I searched for this and didn't have any luck.

My truck has done this from day one, but of course, when I have brought it in before, it never acts up.
It does this from time to time, it really did it bad today. I'll just crank her up and sometimes when she just sits there, it won't find a proper idle and it just bounces b/t 500 - maybe 1000 rpm's and just sounds silly. Like I'm lightly tapping the gas pedal. This mostly happens when the engine is cold, but it has happended before after a decent travel distance.

I know its not supposed to do this. Sometimes I'll back up a little, put it in park, and then it starts that jumping again.
Usually if I just give it gas and run the rpm's up while I'm in park, it will finally idle out where it's supposed to be.

Anyone else's F150 do this??? Mine is a 2002 F150 reg cab with a 5.4L automatic. Very troubled by this and I would like to fix this silly engine idle problem!!!

Rob

 

IAC valve.

 

Could you explain that one a little bit?

If that is a valve I need to change, I'd be glad to.

 

OK, Idle Air Controller valve.

Where is that found?

 

Either clean or replace the Idle Air Control (IAC) on the back of the throttle body with throttle body cleaner, and see if that helps. Actually, after I cleaned mine the first time it did that for a little while then gone. It kept acting up year after year so I bought a new one and it runs brand new.

 

Thanks gents.

Will try to find the IAC on back of the throttle body today!!


Rob

 

It's that little aluminum piece with a shiny can attached and a plug on that that sits on the t-body elbow and is right under the cowl. You'll for sure find it. Be careful when removing it, unplug first then don't loose the bolts and the gasket. Everything should be cool then, a first step before you gotta replace it, not cheap, over 100.

 

Mine was doing that for a while...I seafoamed it and it hasn't happened since.

 

When you say you seafoamed it, did you use seafoam to clean the IAC, or did you do a seafoam treatment on your truck.

I am interested in this "Seafoam" stuff.

RL

 

If your looking for a cheaper option than replacing it. I cleaned out my IAC with some carb cleaner a little over a year ago and haven't had any problems since.

 

I just did the seafoam treatment to the truck. I didn't touch the IAC. Sucked it in through the brake booster line.

It idles much more smoothly now and I don't get the fluctuation.

 

I did a search on here and found a good bit of info on the seafoam. I saw the picture of the brake booster line.

Does anyone have a picture of where the IAC is?

Another question, I can see how running seafoam through the gas tank would work, but the brake booster line? I am trying to figure out how that would work.

RL

 

It works because it sucks the seafoam directly into your engine.

 

Yup, I tink I may have to try some.

 

The aerasol brand of SeaFoam is called Deep Creep.You can get it at any NAPA.You should also look into cleaning your throttle body.Go to this website and look under the "how-to" articles about throttle body cleaning;
www.fordf150.net
It also shows pics and has some of the IAC valve!