2000 Jeep

Hi group, I'm new to this forum, but have been in the automotive service industry for 16 years, mainly with BMW and Mercedes Benz. I've recently purchased a 2000 Jeep Grand Cherokee Limited with the 4.7. I'm experiencing an intermittent stall. This stall comes with NO warning. There is no throttle hesitation or surge. The engine just shuts off like a light switch. Immediately I thought it was the crank shaft sensor, so I've replaced that with an OE part. I've spoken to the local dealer and they say that the camshaft position sensor on this engine is required for continual engine run and not just for initial start to fire and sequence the injectors. This stall has happened to me now 5 times in the past three weeks of initial ownership. Conditions have been at light throttle load or at idle in gear or park. I've removed and cleaned the throttle body and IAC, no improvement at idle. As stated before the stall comes with no warning at all and seems to occur after driving 30+ minutes with one or more ignition cycle. It will restart, but it takes anywhere from 5 minutes or more to restart. Which is NOT fun in stop and go Seattle traffic. I have a camshaft sensor that I'm going to install today just because it is $40 and why not eliminate that. I'm quite certain it's not fuel related because there is no stumble or hesitation. So, it has to be ignition related or some type of heat soak problem. Has anyone experienced this before? I've had it outside my shop running since 0730 this morning with a scanner on it monitoring CPS, Cam signal and MAP and idle, but it has not died yet. ANY thoughts would be greatly appreciated.

sounds like the CPS, did you disconnect the battery befor ereplacing?

Altho most of the time when the CPS fails and causes stalling it will usually start right up (w/o waiting). I would look at the Ignition Coil for that one also Fuel Pump, both of these tend to overheat (Fuel Pump tends to overheat when @/under 1/2 tank of gas) and shutdown. Try to monitor you gas guage when the stalling occurs, if below 1/2 tank then chances are the FP is the problem. Ignition Coil is kinda out of the question since you model has Coil Over Plug design, that would lead me to the CPS again.

When you say CPS are you saying Crank or Cam position sensor? We have many BMW's towed in with the cam sensor failed. Had a Z3 in today for that very same complaint. Intermittent stalling while driving.

Crank.

This is the sensor that I just replaced two days ago with OE part. Yes, battery was disconnected. You have to pull the started to get to it.

humm if the batteryw as disconnected and it was an OE (mopar brand) part, then I would look more toward the Fuel Pump, it could also be the cam sensor, but no so common. have you checked for any stored codes?

yes, continually. No codes stored. I'm replacing the cam sensor right now and we'll see. I don't think it's fuel related by the way it just shuts off with no warning. Fuel starvation problems give warnings by stumble, hesitation etc.

I think you are on the right track.I agree that if it was fuel it would not be a sudden stall,but if it loses cam or crank I would expect a code,especially if you can't get it started right away.Does your scanner tell you how many starts since dtc's were cleared?It sounds like a pcm problem,possibly that it is losing ignition feed or maybe a bad asd relay.That's the auto shutdown relay,which is actually a confusing name since it powers things when on,not shuts them down.I would try the cam sensor,its cheap and easy,but I would also either replace the asd relay or swap it with one of the other relays like the starter or horn relay etc.Or if you swapped it with the fuel pump relay and it causes you to lose fuel,then you would know for sure.

I replaced the camshaft sensor on Friday night and have exhibited this problem since. It went to die once just like before with no warning and immediate shut down, BUT it didn't shut down. It came back as quick as it would die. Makes no sense. I didn't have the scanner hooked up at this time, so I wasn't able to check live data. I hooked it up with the engine still running and there were no fault codes stored. This is usually the case. Do the cam and crank sensors need to sync. up together somehow? I drove it yesterday with no failure, this am no failure either. Where is the ASD relay located? I could take the relay apart with a new one in the other hand and see if there are any shorts or hot spots on it. I had an intermittent problem with the wipers on my BMW that had that same type of complaint. So, a relay could definately be the problem. What is the function of this relay?

Thank you for all your help..it is much appreciated.
Derek

Derek,

It still sounds like a bad CPS. The stalling then restart by the engine is a very common symptom of the CPS. I am sure if you search on the forum for stalling issue you will see some folks had the same thing happen and it was caused by a bad CPS.

I think it's fixed, but another problem has arrisen in the process. Longer cranking when cold. So, I'll run the fuel level down and replace the pump assembly and O-ring. I believe the repair to cure the stalling problem was the vehicle speed sensors. I ran the Jeep in my shop parking lot all day long and it did not stall which proves that it has to speed vehicle speed to stall. Since the VSS's have been installed it hasn't stalled once. Keeping my fingers crossed. Thank you all for your help.