JT4x4

The Mud Pit => Wrenching => Topic started by: CnoteTJ on April 22, 2008, 02:05:15 PM

Title: Rough idle
Post by: CnoteTJ on April 22, 2008, 02:05:15 PM

So, yesterday i noticed my jeep was idling rough on the way into work.  Once I got to spend a little time on it I noticed that the vacuum line for my heater and cruise control(havent used either in a long time) had come undone.  Now, when I push in the clutch and pop her outta gear she starts loping like a drag racer with a heavy cam  >:( (between 500 rpm and 1000rpm)  any ideas on what the problem might be?  Let me know...

Title: Re: Rough idle
Post by: rocket on April 22, 2008, 02:24:58 PM

sounds like a vacuum leak.  check all lines, check manifold vacuum, check pcv valve.

Title: Re: Rough idle
Post by: HOT-ROD on April 22, 2008, 05:05:14 PM

check your idle adjustment. sometimes it backs off and lowers your idle. i would lean towards a vacuum leak with the clutch master. seem likely when you drop off the pressure the engine drops rpm's.

Title: Re: Rough idle
Post by: CnoteTJ on April 23, 2008, 08:38:18 PM

more info on this...this only occurs when I am driving somewhere, after sitting for two minutes it is fine

Title: Re: Rough idle
Post by: Seabee_BUC on April 23, 2008, 09:47:44 PM

I would suggest it's the fuel filter. Under load and driving, it could get starved for fuel especially with all your performance mods. When it sits, the engine gets plenty, because the pump can keep up with it. With a clogged filter, flow is severly diminished. I'd look into an adjustable fuel pressure regulator too, just bumping up 2-3 lbs. is a fine improvement in fuel delivery. It might not be $$ friendly due to gas prices right now however.

Title: Re: Rough idle
Post by: CnoteTJ on April 23, 2008, 11:49:53 PM

after re verifying every vacuum line, and looking for any other visible problems today, i talked to one of my mechanic buddies (ASE certified), after explaining my problems he recommended taking the neg cable off the battery for 5 minutes since i had that vacuum line disconnected, to reset the computer.  i did so and after a short drive around new london, only once did I have a slight problem at idle(it just hung low round 500 rpm) but no more loping, im working 3rd shift the rest of the week starting tonight so ill see how she acts after a highway mile.  hopefully no more problems *fingers crossed*  like fuel filters, iac valves, and pcv valves.  thanks for the ideas and help guys!!