Low idle when warmed up. Not sure what it could be.

[manche75]

Ive got an mj with the 4.0l in it and has a low idle(500 rpm and lower). This only happens when warmed up, and on summer days. I noticed the idle at initial startup started to become more normal as the weather got cooler. Sometimes wants to stall out but never does when warmed up. Does anybody have any suggestions???

[glundblad]

Mine experienced a similar problem. I replaced all the obvious "easy" things such as plugs wires, coil, tps, etc. but nothing worked. I took it to a mechanic. He replaced the solenoid and EGR. Ran like new after that.

[exjay33]

Give it a good dose of seafoam , then check for vacum leaks clean and or check egr.

[KYMJ]

Check the plastic line from the Map sensor on the firewall that goes to the throttle body. The rubber connector between the plastic line and the Map may be cracked on the backside. A start anyway, it happened to mine.

[comanche09]

My truck idles at 500 regardless of engine temp. Runs great otherwise though. It did stall on me once after pushing in the clutch coming to a stop, but fired right back up.

 

What is the normal idle range?

[Geonovast]

Every 4.0 I've had idled at 500-700.

[comanche09]

Every 4.0 I've had idled at 500-700.

 

Thanks Geonovast, did they all Idle in that range even when cold?

 

Maybe I'm just used to newer cars with the cold start high idle for emissions. My '07 Aspen won't even go into overdrive until the engine has reached a certain temp.

 

My idle dead set at 500 ice cold or at operating temp...

[Geonovast]

Yup..

 

Your IAC may be dirty. It would be a good idea to pull your throttlebody, pull the IAC off (Leave the TPS ON!), and spray everything down with an O2 safe throttlebody cleaner, and scrub it good with an old toothbrush.

 

IAC being stuck/dirty is the cause of a good number of idle problems. My XJ will idle at about 2000 for about 15 seconds every once in awhile right after startup.