I have the good ol' rough idle in my 03 5.4 auto. Removed and cleaned IAC last night and re-installed. No change in rough idle. Should I spray the MAF or clean the TB next? If all 3 of these don't do it, I'll go on to plugs, wires and cop's.

 

check out the TB and the elbow behind it. those seem to be the most common.

 

thanks, I'll check it out tonight

 

Have you considered servicing/cleaning the injectors ?You can purchase a service kit that attaches to fuel rail.

 

If the truck runs fine (except at idle) the first thing I would look for is a vacuum leak. The injectors would be the second thing I would suspect assuming you have good gas in the tank.

 

Explain what you mean by 'rough idle'? Does is fluctuate up and down? Does the truck shake? Give some examples. My truck shakes/vibrates at idle when warmed up. I've replaced COP's, spark plugs, you name it. No luck.

Anthony

 

My rough idle is in park or in gear, rpm's fluxuate between 550 and 700, sometimes it idles literally perfect, sometimes it feels like its gonna stall (but never has), and when it's real bad, feels like someone is on the outside of the truck shaking it back and forth real fast, I can feel the vibration through the floor in waves of smooth and vibrating. Under accleleration or driving at any speed, it is very very smooth.

 

ya I run 91 or better from chevron or 76, and it has happened on every tank of gas I've ever bought (I installed a superchips, that's why I run 91 - before that i ran 87 as specified by the manual).

 

where do you get one, and how much do they go for?

 

Masonball,pull your air intake and then open the throttle.Get a flashlight and look into the TB.If it is filled w/ sludge then remove the TB and elbow from the intake and clean them.Be sure to also clean all of the ports out.Get your gaskets first,i could not find them local so i ordered from ford.I used brake cleaner to get the sludge out and then lubed it up w/ WD-40.If i remember correctly you have relatively low miles like 80,000 correct?

 

Ya - about 76,500 - how'd you remember that? anyway, I can take off the air intake, but do you mean to take it off with the engine on and look in it then? Which gaskets are you talking about?

 

Good memory i guess i remembered from your rear end prob and i remember numbers well. Hell no don't start it,leave it off.There is a TB gasket,Then there is a gasket on your elbow where it bolts to the lower intake.You als need a new EGR gasket.

 

cleaning that throttle body makes a big difference. did mine last week and its much more responsive and has more pep. it has 130k and runs like new. i couldnt get that egr tube off though. so i couldnt get to the egr ports. didnt have the right size wrench. o well

 

How long did it take you to take off the throttle body? What did you clean it with and where does it need the most cleaning?

 

took me about 20 mins. i didnt take the whole thing off though. i cleaned the throttle plate and the i.a.c ports. the e.g.r ports are what usually needs the most cleaning.i sprayed the cleaner in there but i heard its best to take a small brush and scrub it out. if anyone knows what size wrench that e.g.r. nut is that goes into the throttle bidy met me know. couldnt get a pipe or big adjustable in there.