Yesterday, I traveled to Nashville to check out my son Will’s Jeep. He had called complaining of a severe stumble and stalling in traffic. I remembered that this was a problem when I bought this Jeep for him.
When I first arrived, his Jeep would not start. I was finally able to start the Jeep but it did not idle correctly.
I took it for a test drive and found that the idle air controller was sticking and allowing the engine to stall in traffic. Unless I was really alert when decelerating, the engine would stall.
I made my way back to his apartment and used carburettor cleaner to clean the idle air control circuit in the throttle body. After a few squirts the valve started controlling again and was able to catch the engine when it slowed down.
I noted that there was a lot of oil sludge in the throttle body so I checked the vent from the valve cover and found it partially stopped
up. The connection at the manifold was also clogged. I used the carb cleaner to clean the tube and the connection.
I never experienced the stumble but I suspected it was caused by the ECU connection. I removed the big connector from the ecu and wired down the connector. If I had had some contact cleaner handy, I would have sprayed the contacts before re-seating it. The folks at Hesco say there is a common failure of the ECU due to over tightening of the connector bolt. The circuit board cracks here or the threadsert pulls out of the board.
I put just a small amount of torque on the bolt as I tightened it back in place. We let the engine cool a bit and then took it for another test drive. It ran fine taking us to dinner and back. I hope this will cure it for a while.
I also showed Will how to do these checks himself if it does act up again.