jeep 4.0 with extremely low idle

cheapcherokee89

Active Member
Joined
Sep 9, 2006
Location
oxford
I got a 97 grand Cherokee with the 4.0 in it that seems to have a idle issue. when I crank it up for the first time each day it is idling around 300rpms. Its not shutting off its just a really rough low idle. Once the jeep has warmed up its fine. It has a new TPS sensor already on it and isn't throwing any engine codes. If I pull the brake booster hose loose it will idle on up, so that would make me think its not getting enough air. Any ideas would be greatly appreciated. Thanks
 
take a propane torch,turn it on (not lit) and with the engine running,go over all your vacuum lines,if you get a surge in idle thats your leak. this might help you or may not. good luck
 
Had a similar issue and just had to clean the idle air control valve. Did a light cleaning on the throttle body as well since it was all torn apart.
 
Just cleaning the butterfly valve in the throttle body will help. I had some much oil in the air filter hose and on the throttle body from oil blowback and it was messy. Some cleaner cured my random high idle. Next thing I would check is a vacuum problem.
 
NASH-TY-AMC said:
take a propane torch,turn it on (not lit) and with the engine running,go over all your vacuum lines,if you get a surge in idle thats your leak. this might help you or may not. good luck
Click to expand...
A vacuum leak on a map engine typically causes high idle. I would take a look at the IAC circuit and make sure its functioning. It would be easiest by using a scan tool and vie desired idle vs actual idle. Typically a difference higher than 200-400 rpm will set a IAC code. Some Chrysler products required a IAC relearn for some procedures. As also mentioned above a dirty throttle body can cause a low idle to an extent.

Sent from my DROID RAZR using Tapatalk 2
 
cleaned the throttle body and idle air control valve yesterday and its idling perfect now....but just my luck the crank sensor went out last night. $40 later I had it back on the road running and idling great! thanks for the help
 
Back
Top