AndyS
NAXJA Forum User
- Location
- Shrewsbury, MA
A guy I work with presented me with the following problem tonight, so I thought I'd see what you all had to say....
He has a '98 4.0 ZJ which has a cold idle problem. If the engine is cold, or has been sitting for over 30-40 minutes it will start just fine and idle normally for about 10-15 seconds. At that point, the idle speed drops to 500-ish, and it chugs and barely keeps running, and it sounds super-rich, although I didn't check to see if there was soot blowing out the exhaust. A couple of times, it dropped to nearly 0 rpm, then caught itself and surged up to 1500 rpms for a sec and then back down to 500.
This goes on for a minute or so, then it clears up and he's able to go on his way. If he tries to drive when it's acting up, the vehicle has no power, and it will barely move - once it clears up, no problems.
It seems like a temp sensor to me, with the way it just clears up, but it will do it whether the engine is stone cold or has just been sitting for a half hour or more, despite what the engine temp seems to be. Any suggestions?
Thanks!
He has a '98 4.0 ZJ which has a cold idle problem. If the engine is cold, or has been sitting for over 30-40 minutes it will start just fine and idle normally for about 10-15 seconds. At that point, the idle speed drops to 500-ish, and it chugs and barely keeps running, and it sounds super-rich, although I didn't check to see if there was soot blowing out the exhaust. A couple of times, it dropped to nearly 0 rpm, then caught itself and surged up to 1500 rpms for a sec and then back down to 500.
This goes on for a minute or so, then it clears up and he's able to go on his way. If he tries to drive when it's acting up, the vehicle has no power, and it will barely move - once it clears up, no problems.
It seems like a temp sensor to me, with the way it just clears up, but it will do it whether the engine is stone cold or has just been sitting for a half hour or more, despite what the engine temp seems to be. Any suggestions?
Thanks!