When i first got my truck about 5 months ago it idled around 1000 rpm now it idles at 1500 to 1900 warmed up or cold...i have a 2002 4.0L.....what could be causing this?

 

elec. choke sticking??

 

thanks for the quick reply...i'll look into that...when i'm driving a push in the clutch the rpm's won't always drop it will stick at 2000 or what ever i'm at...this is a ocasional thing not to often but its been hapeing more lately

 

could also be a vacuum leak....

mine used to idle high and i found a vacuum hose popped off

but i dont have the same engine or fuel injection....just an educated guess

 

yea i checked all the vacuum lines and none of them were loose or off...that was my first guess on the problem....it ain't bad the truck still runs fine it just idles way to high

 

Sounds to me like your idle was too low and now is too high.

I'd clean the TB plate and bore with a tooth brush and some soapy water.

Rich

 

His idle was low at 1000? Both my dad's and I's 4.0l ohv's idle at about 1000rpm

 

It's possible that different years idle differently.

My 06 in stock "tune", idle speeds will rev to 2200 (or a little more) then slowly come down to the final rpm when the ECT reaches 170F.

I've gone in and commanded at least 500rpms lower rpms at temps above 20F. (20F and below I've pretty much left alone so as to keep fords design intent)

As-is I now start it up in say a 45F temp and the revs will go to 1800 for just a second and then settle into a 1300. Then as ECT temps raise the RPMs drop.

btw, there are several things that the PCM looks at before it commands a certian rpm.

Rich

 

Try unplugging the electrical connector on your IAC. If the idle speed doesn't drop down, try cleaning the IAC, but you will probably have to replace it.

 

thanks for the ideas guys i'm gonna look into them