Issue with engine shutting down while driving.

[dani9678]

I'm working on a 1998 Jeep Grand Cherokee Laredo 4.0L that belongs to my uncle. What happens is it wants to shut off while driving. It starts around 15 minutes after started. I found that the bushing in the distributor was worn out to the point that the rotor would bounce around inside. He had already replaced the ignition coil prior to this. I figured that this was the main issue so it was swapped out. It didn't help with the engine shutting off. It does run much smoother now of course and seems to have more power. Anyways, I noticed that the replacement coil seemed to be getting hotter then I figured it should so he swapped it out again. I have a Matco Determinator Analyzer that I connect to it. There were two codes that were stored. One was P0108 I believe and the other was P0351. I think the first has to do with MAP pressure being to high and the second was the coil. After clearing the codes, he took it for a drive again and when it shut off, there was another code thrown. I found that it was P0108 again. I believe the reason the code was thrown was because the ignition was still on when the engine shut off so it sensed the sudden change in the vacuum and threw the code. I have since cleaned all connections to the ECU, harness, and connections to the CKP sensor, Distributor connection, and ground points. I noticed there was another person having the same issues and somebody asked if his reverse lights were working. The ones on my uncle's Jeep aren't. He said that it could cause problems with the engine shutting off. Is this true? The guy ended up replacing his crank sensor and had no more problems. I don't want to have my uncle go out and buy a sensor just to find that it didn't take care of the problem. He also stated that when the engine shuts off, you can smell raw gas. This leads me to believe that the fuel pump is still running when the engine shuts off. Any help would be greatly appreciated. He is relying on me to get this right and I don't want to keep throwing parts at it. I have also jiggled all connections while it is running to make it shut off but it doesn't happen.

Thanks,

Matt

 

[RCJP]

I'm working on a 1998 Jeep Grand Cherokee Laredo 4.0L that belongs to my uncle. What happens is it wants to shut off while driving. It starts around 15 minutes after started. I found that the bushing in the distributor was worn out to the point that the rotor would bounce around inside. He had already replaced the ignition coil prior to this. I figured that this was the main issue so it was swapped out. It didn't help with the engine shutting off. It does run much smoother now of course and seems to have more power. Anyways, I noticed that the replacement coil seemed to be getting hotter then I figured it should so he swapped it out again. I have a Matco Determinator Analyzer that I connect to it. There were two codes that were stored. One was P0108 I believe and the other was P0351. I think the first has to do with MAP pressure being to high and the second was the coil. After clearing the codes, he took it for a drive again and when it shut off, there was another code thrown. I found that it was P0108 again. I believe the reason the code was thrown was because the ignition was still on when the engine shut off so it sensed the sudden change in the vacuum and threw the code. I have since cleaned all connections to the ECU, harness, and connections to the CKP sensor, Distributor connection, and ground points. I noticed there was another person having the same issues and somebody asked if his reverse lights were working. The ones on my uncle's Jeep aren't. He said that it could cause problems with the engine shutting off. Is this true? The guy ended up replacing his crank sensor and had no more problems. I don't want to have my uncle go out and buy a sensor just to find that it didn't take care of the problem. He also stated that when the engine shuts off, you can smell raw gas. This leads me to believe that the fuel pump is still running when the engine shuts off. Any help would be greatly appreciated. He is relying on me to get this right and I don't want to keep throwing parts at it. I have also jiggled all connections while it is running to make it shut off but it doesn't happen.

Thanks,

Matt

Hi,, I 've been havinf the same issue for aLOOONG time now let me tell you What I have replaced and still have the same problem...
CPS
TPS
MAP
IAC

Even took the CAT converter out thinkg it was clog issue because of the smell of gasoline .. have not replaced it, right now I had a straight pipe installed.

mine also shuts off around 15min of driving and some times after 15 min of just idling in my driveway..One thing with mine the ECM got fried A couple of years ago and had to get a new one from the dealer after a year or so all my issues started by the time i tough about claiming warranty on it it was expired.

the stalling issue on myne has gone down to the ECM having loose connections between the its cover and the inside connectors.

but all of this has evolded into not beeing able to rev the motor with out getting backfir ont hte INTAKE ...

any I like you am still looking ,,,
good Luck

 

[RCJP]

Hi,, I 've been havinf the same issue for aLOOONG time now let me tell you What I have replaced and still have the same problem...
CPS
TPS
MAP
IAC

Even took the CAT converter out thinkg it was clog issue because of the smell of gasoline .. have not replaced it, right now I had a straight pipe installed.

mine also shuts off around 15min of driving and some times after 15 min of just idling in my driveway..One thing with mine the ECM got fried A couple of years ago and had to get a new one from the dealer after a year or so all my issues started by the time i tough about claiming warranty on it it was expired.

the stalling issue on myne has gone down to the ECM having loose connections between the its cover and the inside connectors.

but all of this has evolded into not beeing able to rev the motor with out getting backfir ont hte INTAKE ...

any I like you am still looking ,,,
good Luck

OO yeah I also get the 351 error dwell time... changed the ignition coil twice...no LUCK ..mine is also a a 98 GCL 4.0L

 

[dani9678]

well ain't that somethin. I ended upcleaning all connections, removing the ECU and cleaningit's connections, cleaning and sanding the grounds, and battery terminals. Did you say that you replaced your crank position sensor also?

My uncle wants to give it to his daughter but doesn't want it to be doing this when she gets it.

I noticed that someone said that if the reverse switch is bad then that could cause it to shut off but I don't see how unless it tells the ECU to kill the engine if it thinks that you have accidently put it in reverse while driving to prevent damage. I disconnected the connector to the switch and jumpered the two outer terminals to get the reverse lights to work. When I connect my analyzer up and read the datastream, it doesn't see the selector move until I plug the switch back in so apparently there are two switches integrated into the housing.

Do your reverse lights work?

Oh and He drove it the following day after I cleaned all connections and it ran great he said. Until this morning when it shut off 3 times on him. I pulled another P0351 code again. It showed 3 starts since set.

 

[RCJP]

well ain't that somethin. I ended upcleaning all connections, removing the ECU and cleaningit's connections, cleaning and sanding the grounds, and battery terminals. Did you say that you replaced your crank position sensor also?

My uncle wants to give it to his daughter but doesn't want it to be doing this when she gets it.

I noticed that someone said that if the reverse switch is bad then that could cause it to shut off but I don't see how unless it tells the ECU to kill the engine if it thinks that you have accidently put it in reverse while driving to prevent damage. I disconnected the connector to the switch and jumpered the two outer terminals to get the reverse lights to work. When I connect my analyzer up and read the datastream, it doesn't see the selector move until I plug the switch back in so apparently there are two switches integrated into the housing.

Do your reverse lights work?

Oh and He drove it the following day after I cleaned all connections and it ran great he said. Until this morning when it shut off 3 times on him. I pulled another P0351 code again. It showed 3 starts since set.

Yes i did change that sensor but I should mention that it was a USED sensor it turned out to be worst were it would never start so the put mine back on and it started fine .....I also have done a lot of stuff to it that makes it run a lot better but the stalling come back after a day or two...I have not checked that part yet. and since I broke my battery terminals while cleaning the corrosion this morning I wont be able to check that until later. first time i have hear of this. I will look into service manual for any electrical reference.

have you tried the thing with the screws since you have the original ECM It might work ....you are supposed to take the two torque screws that are just bellow the 3 connectors onthe ECM and give it a try if it does not stall try putting screws that 1/2 the size of the original.

 

[billyray40]

Im having a problem with my 98 jeep gc.It stalls when I put it in reverse or drive occasionally,but only does it when its cold.It was doing it before even at operating temp battery bracket was loose tightened it and put new crankshaft sensor on.But like I said still stalls when put into gear cold.I've narrowed it down to O2 sensors or bad battery temp sensor(atleast I hope)I just hate it when something piddly like this kicks my butt.Any help would be appreciated.

 

[nelson46]

have you checked the automatic shut off fuse? i had the same problem replaced it and never had a problem since.

 

[dani9678]

Well, I added spacers to the two screws that go into the ECU and noticed that the ECU went from almost fire hot to just warm and my uncle drove the Jeep for 3 days and then it finally died and would not start again. I have since noticed that the fuel gauge doesn't work, the check engine light doesn't come on when the key is turned to the on position and the mpg gauge just shows a couple of dashes. Also noticed that the fuel pump runs constantly once the key is turned to the on position and will not cycle off. Does this sound like a faulty ECU?

 

[jimbob2001]

Yes it does. Sounds like a Faulty PCM (ECU) There should be Some Engine Codes here --- with all the problems you describe. The Fuel Pump --- Should only Cycle ON for a FEW Seconds--- with the Key ON. Fuel Pump will NOT stay on until PCM sees a CPS signal. CHECK. For Engine Codes --- JB

 

[dani9678]

I'm unable to pull codes because my analyzer cannot communicate with the ECU. It tells me to turn the ignition to the run position when it is. It would link up fine with the ECU before this happened. Do you know which pins feeding the ECU with power that I can check so that I can determine if it is getting power to it like it should? Also which ground pins to check for resistance. I read somewhere that any of the sensors like the CKP, CPS, VSS, and even the o2 sensors can short out causing the ECU to shutdown. If I leave all of those sensors disconnected, will the ECU power up?

Matt

 

[billyray40]

have you checked the automatic shut off fuse? i had the same problem replaced it and never had a problem since.

No how do you check it?With a voltmeter Im guessing.And if so what should the voltage be?

 

[RCJP]

Well, I added spacers to the two screws that go into the ECU and noticed that the ECU went from almost fire hot to just warm and my uncle drove the Jeep for 3 days and then it finally died and would not start again. I have since noticed that the fuel gauge doesn't work, the check engine light doesn't come on when the key is turned to the on position and the mpg gauge just shows a couple of dashes. Also noticed that the fuel pump runs constantly once the key is turned to the on position and will not cycle off. Does this sound like a faulty ECU?

Well if you never see the CHECK ENGINE Light come on when you turn the key, the YES it is and ECu problem but before you get a new, take the screw all the way out disconnect all the connectors that go the ECU, and wait a couple of minutes About 10min. reconnect BUT LEAVE the screws OUT. and turn the key if you never see the CHECK ENGINE light come ON then you may need a new ECU. :shock:

 

[dani9678]

Are you referring to the two screws under the 3 connectors on the front of the ECU?

I mentioned that the fuel pump runs non-stop until the key is turned back off. Will a faulty Auto Shut Down relay or fuse cause the fuel pump to do this?

I had swapped the ASD relay for another identical relay with the same markings printed on top and it didn't make a difference. I also noticed that it would click when I removed and re-seated the ASD relay.

Matt

 

[dani9678]

I found the following site and tried what this person did but it didn't work. This person wasn't getting any voltage on the TPS connector until they unplugged the crank position sensor, then the voltage came back. So, the CKP sensor was bad.

Here is the link.

Troubleshooting: 1998 Jeep Grand Cherokee (ZJ) Doesn’t Start – Cranks, No Fuel, No Spark | tim laqua dot com

Matt

 

[dani9678]

The replacement ECU arrived today. I'm going to be installing it tomorrow. I made sure to match everything between the old ECU and the replacement when ordering. Everything matched except for the serial number of course. Is there anything that I need to know when installing the replacement? Is there any ECU re-learn procedure that I need to know or can I just plug it in and connect the battery? I remember reading somewhere that you had to take it to the dealer to have it programmed to the vehicle.

Thanks,
Matt

 

[dani9678]

I just finished installing the ECU with the same results. No voltage to coil, no start, fuel pump runs continually. Any ideas. This thing is a sitting duck. I can only do so much testing with the engine off. All of the sensors are getting 5 volts. I was told that if I unplug the CKP sensor the voltage would return to the coil if the CKP sensor is bad. That didn't work so apparently the sensor is still good. I am trying to repair this for my uncle and I believe he is beginning to think I'm a dumbass because I have yet to find the cause and he has been paying me as I go.

 

[dani9678]

Do I need to get the VIN flashed onto this replacement ECU to get it to work?
It is a 1998 Grand Cherokee Laredo 4x4 4.0l auto.

 

[SteelHeadz]

The ECU needs to be programmed with the current Vin of the vehicle as well as the odometer. If the vehicle is equipped with a skim system, the security code also has to be programmed to the new ECU.

Do I need to get the VIN flashed onto this replacement ECU to get it to work?
It is a 1998 Grand Cherokee Laredo 4x4 4.0l auto.

 

[jimbob2001]

That sounds right to me. --- How about a little RECAP of what PARTS --- Have Been replaced on this JEEP-- To address this Problem? Also, with the NEW ECU -- Can You pull up any OBD. Codes? The ORIGINAL problem -- Shutting down while Driveing -- SOUNDS LIKE an Electrical ISSUE! Perhaps, a. POOR Electical Connection--- ( ECU or ASD Relay). Has the Fuel Pressure been OK? If so -- it is most Likely An Electrical Issue. Do You HAVE a DMM. (Multimeter?). Very Handy! -- JB

 

[dani9678]

The replacement ECU works fine now. It turns out that a fuse had blown. Apparently when the other ECU finally went bad, it pulled additional amps taking the fuse out with it. It reminded me of a light bulb that's at it's brightest just before burning out. Anyway, it's running good now. I just finished swapping in another exhaust manifold (looks more like a header) due to fractures at the weld points. I still need to swap in the new o2 sensors. I figured with almost 200k on the clock that a fresh set of o2 sensors wouldn't hurt. Oh, and the analyzer now reads the ECU fine along with the fuel gauge working and the check engine light now cycles on and off right after the ignition is turned on.

I have attached some pics of the old and new exhaust manifold.


Matt