96 Jeep Grand Cherokee 6cyl. 2X4 Intermittantly Cuts off


#1

This is a reposting: Still having trouble! Help…someone must know what gremlin has crawled into this thing!

I have changed Cam and Crank sensors and coil, replaced TPS. Checked the Idle Air Control Valve…checked out fine. tested MAP sensor…no issues there. It will cut off sitting at a light. Foot off gas. It cranks right back up and it doesn’t do it every time you stop.



No codes showing up on the pocket tester. I have swapped the relays previously suggested…it has helped to do that…but not fixed problem. Idle speed is in the 800 range with A/C on does not change much with A/c off. Idle goes up when you start it and comes back down to normal. Took it to dealer and was told the fuel pump was going bad…replaced the fuel pump. Fuel filter is less than yr old. Fuel tank was clean. It will buck a little then cut off. Or like today, Stopped at a light. Light turns green. turn the corner and suddenly there is no power…won’t rev. won’t go. Pull off to side of rd. put tran in neutral. Eng. revs. normal. Put it into drive and drive 2 more miles to destination…no problem. Car sits for 20min. get in and drive 10 miles…no problem.


#2

The engine suddenly shutting down usually means there is an ignition system fault.

You may find this fault by plugging a scan tool (terminology?) into the OBD11.

Because the fault is intermittent, it may take awhile.


#3

It would be very helpful to know if there any other clues to go on when this problem occurs. Do any warning lights appear when it does this? When you turned the corner was the engine still running but did not respond to throttle changes, or did it die?

I assume the fuel pump relay has been changed out. The ignition switch area and relay are other possibilities. I suppose problems with the transmission control unit may be a cause also but I would think a code would be set if that was the case.


#4

No Codes show up on scan tool. Originally got Ign. Coil code. Cracked coil…which was replaced. No codes now.


#5

It was still running and no response from pressing on gas pedal until she stopped and put it in Neutral…then eng. revd and she put it back in gear and drove home. Within 1/2 hr she drove back to work and had no problems. When she drove home later…no problems.


#6

No dash indicators. No codes. Fuel pump and relay are in tank…both are new. I have not changed plug wires yet. Have not pulled injectors yet but they are all clicking the same when I listen with stethoscope.
All relays have been checked and or changed. Have not changed MAP sensor but VoltOhm showes it is perfect in range specified.


#7

Okay. So the engine appears to be happy when this trouble occurs. From what you say it looks to me that there may be a problem with the PCM module or there may be a bad signal coming from the transmission control unit causing the engine to not respond to the throttle changes. I am assuming that since there isn’t a TPS error code that there isn’t a problem with the circuit to it.

One thing you might try is just disconnecting and reconnect the connectors to those modules to see if that may help stop this trouble. Faulty connections can cause all kinds of strange things to happen, depending where they are at.


#8

I have not checked the Transmission related issues…but this thing does have the cold weather 1st gear transmission slip that is inherant in many Jeeps. I’ll check that. Then we are down to some fault in the PCM. Sheesh this has been one tough one to crack. Thanks for the help though…I will keep at it.


#9

Those are my best thoughts on where I think the problem may be at. I could be wrong. There may be other areas I didn’t think about.


#10

Looks like the problem has been discovered. Bad connection at the PCM. A couple of the wires in the harness had become worn internally. Thanks to everyone and the numerous suggestions. Took it to the dealer to put it on main computer diag. machine…took two days to finally get it to act up. Old salt of a mechanic figured it out.