1994 Jeep Laredo occasionally rough idle/RPM surges

DDNOAKES

MEMBER
1994 JEEP GRAND CHEROKEE LAREDO
6 CYL
4WD
AUTOMATIC
137,000 MILES

I have a 94 Jeep Grand Cherokee with 137000 mileage. I have recently installed a new battery, new alternator, radiator, tires, brakes, and two new engines mounts. Other than regular maintenance these are these only repairs I have had to do on this vehicle in 14 years. The jeep runs great, however, it recently started having some type of occasional rough idle at traffic lights and when backing out of parking spots. A few times it has stalled; however, it starts back up just fine). This rough idle is very sporadic though. Sometimes the jeep will also jump up in rpms as I am pulling away from a traffic light. The jeep runs smoothly at higher speeds. I was told that it might be a catalytic converter problem. I recently moved from New Mexico to Ohio. I will be driving the vehicle from Ohio to Florida and want to make sure the problem is corrected. Discovered that the jeep was low on Transmission Fluid. Now Jeep is running great.

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody