2002 SCab 120,000 miles 4.6 auto. No codes. Rough idle worse when warm. Replaced spark plugs 1000 miles ago. Replaced PCV hose. Tested TPS within specs. Tested egr with vacuum truck stalls and dies. Removed pcv hose and truck stalls and dies. With truck running
removed connector from aic and no real change. Removed aic and tested with 12volts and pintle moves slowly. Cleaned aic again. Does pintle completely close the chamber? Mine didn't.
Any suggestions for rough idle?
John

 

Sounds like the IAC needs to be replaced.

 

Use only a motorcraft IAC. Almost all others will cause a intake farting sound and not fix the problem. When you replace it make sure the EGR port and and throttle body are clean too.

 

What's AIC ?

Air Intake Coolant?

 

My bad. Idle Air Control valve.
John

 

I agree that a Motorcraft part is best but my grandson put an Autozone IAC on his 98 4.6 and it works fine.

 

I've use a couple of autozone IAC's with no issue.

 

I tried one of those and the intake sounded like one longass fart. Got a motorcraft for 42.00 bucks and no more gas...lol

 

I've used the autozone part with no issues but I do agree all things being equal the motor craft part is vastly superior. I didnt know about Rock auto or Tasca. Dealers around here mark all parts up 250 percent. The autozone IAC was about $45 and the dealer wanted about $175 for it. I would order it from Rock Auto now.

 

Yup, that's how it is.

 

Commonnn.. Deep down we know you loved it.

 

From one old fart to another such as yourself, That there was funny!

 

The old ones are the best, -at times critical. So how'ed we get on this basking in the avionce subject? Or is it just me. (?)

 

Replaced the Idle Air Control valve a few days ago. I have driven it around. I continue to have the rough idle only when warm. Again no codes.
Any other suggestions? No variation to RPM's(650), just rough idle at times feels like a stumble.

 

Could be a vacuum leak once things expand that causes a lean mis.