question is in the title. its a 2001 dodge ram 1500 v8 4x4 318 bald/plugged tires. well the tires dont matter. just thought id throw that in there.

 

600-800 rpms thats usualy wat my truck is and my dads old 2001 was. obviously its gonna be higher when you first start it, when its cold

 

When mine was really cold this past winter, it would sometimes idle around the 1000 RPMs or slightly higher mark. Once its warm, or if its already a warm day, 600-800 is normal. Mine does 800-ish right now, but that's just because Hemifever accidentally set my idle speed 100 RPMs to high in the last tune he gave me. He swears he'll have it fixed in the next tune he writes me, even though I told him no big deal. He's got excellent customer service.

 

i did the plenum fix and now im idling around 1000-900 . before the plenum issue it idled around 600. What could be the issue?

 

Did you disconnect the battery when you did your plenum fix?

 

cold idle should be around 1000. warm idle around 600.
IAC controls this.

vac leak will cause increase in idle rpm.
could you have a vacuum line off ?

to prove that you do/don't have a vac leak in a line, you could temporarily disconnect and cap off all vac ports.

 

yeah i disconnected the battery and i tagged all lines, hoses, plugs and cables. It idled around 600 on startup after fix and it was smooth with no problems. after about 30 miles on it it started the high idle

 

900 on cold start, consistant 600 when warm. (between 2nd and 3rd line..i assume is 600)

 

ok, its getting more complicated.
was the return to high idle with all hoses reconnected, or disconnected.

a few more things to try. with idle high, reset pcm and see if problem disappears temporarily. this would indicate the pcm is learning the high idle based on feedback.

with idle high, recap all vac lines and see if problem disappears. this would indicate a vac leak opening up in the evap system (or somewhere).