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hawaii50 07-03-2007 09:45 PM

1997 Grand Cherokee 4.0 Random Stalls
I will try to be brief. I have not seen an exact replication of the problem I am having:
2 weeks ago, my 97 4.0 Grand Cherokee starting randomly hesitating every now and then as if either the ignition or fuel was switched off and back on. Then it would stall at idle randomly. The next few days, no problems, ran like a champ.

Suddenly it would not start whether cold or on the second start after running just fine. It cranked fine, but would not fire up. Once started it would stall after a couple seconds.

My neighbor put his scanner on it, and it said it needed ignition coil. We changed that and plug wires (already has new plugs, new cap/rotor, filters, etc.). No change.

Next, we changed the fuel pump. There was some sand in the bottom of the tank somehow, but who knows how long that has been there...we removed/replaced the pump along with screen filter. Then we completely cleansed the tank itself.

It did not run right away, but then randomly ran for over a solid hour driving without problems. Then out of nowhere started stalling out/dieseling again.

Changed the battery and terminals as they looked trashed and maybe the previous owner had jumped many times for some reason. Eliminated this as an issue,but same thing...would run some, stall, etc. Then ran for over an hour both idle and driving.

Have now spend $600 and have no progress. It runs amazing for a while, then cuts out for no reason, then right back. I honestly dont think the sand we cleaned out has anything to do with it...seems electrical to me. But what? Not sure.

Please advise if you have any ideas. It is much appreciated. I cannot keep changing random parts in hopes of a fix. No code shows up at all and the check engine light is not on (never has been either).

Thank you.

a70eliminator 07-03-2007 10:37 PM

crank position sensor
The crank position sensor will randomly kill you engine and cut in and out just like you describe and when it does start it will run for a couple seconds and quit again. It's located in the bell housing on the driver side at about 10:00. just 1 bolt to remove it unplugs and pulls right out but it can be a little difficult to reach unless you have little girly hands like I do. A new one costs about 50 bucks at autozone.

hawaii50 07-04-2007 04:10 AM

Thank you much, I think it is worth a try for $50. I will install and let everyone know how it turns out.


hawaii50 07-06-2007 08:11 PM

Well, after replacing the Crankshaft Positioning Sensor, nothing...ran great for a while in various driving conditions, now it will not start again. My research on this forum and Google show maybe the camshaft positioning sensor or ECM...I am at a loss. Been happy with this vehicle now the first thing that gives me trouble seems to be never ending. Going on 2 weeks now and cannot seem to fix it.

zjkid 07-06-2007 11:29 PM

Does it only happen at idle or all the time?

Ewout_vB 07-06-2007 11:35 PM

If it is only @ idle then it could be the IAC.

hawaii50 07-07-2007 03:55 AM

It happens while driving or at idle.
Another mechanic came over today and said he is 99% sure it is the pickup (under distributor cap) - his theory is that as that piece gets warm, which it isn't supposed to, it cuts out and is trying to spark...the cutout and stalling is like instant off and on, but hesitates before a stall...diesels at near 0 RMP...I will post tomorrow evening (your time as I am in Hawaii) and let you know what happens. I will research IAC, as I am not sure what that is. One of my other friends who is a great general mechanic suggested the pickup be changed anytime a coil is done, which is the first fix I tried from the code on the scanner...but did not realize it was easy to get as some are integrated with the distributor.

Thank you all for adding input, I am $900 into this string of repairs and hopefully almost done. Intermittent issues are the absolute worst. I wish I would have researched this BEFORE I started throwing money at probability.

Ewout_vB 07-07-2007 08:47 AM

The IAC is a little piston that controls the amount of air that goes through the bypass channel in the throttle body. So when you're not giving throttle this essentially controls the airflow and thus RPM of your motor when the main butterfly valve is shut.

Mine was clogged up and dirty and this caused the engine to randomly idle high and low sometimes staying at 0 RPM for more than a few seconds. Of course this wasn't actually 0 RPM but the gauge displayed it.

The IAC is the thing on the side of the TB where you have the slit above the butterfly valve. It's pretty cheap to replace or you could just clean it. It's held in place by 2 torx screws.

This though is only when it's doing it @ idle, whether standing still or while driving. Whenever you 're NOT giving throttle, or opening the butterfly valve in the TB.

hawaii50 07-07-2007 11:26 PM

idle and rev
Unfortunately for me, it happens on rev sometimes or steady driving too.
Funny thing is, every time I have replaced a new component, it drives amazing for the first it is fixed...cannot make it hesitate, stall, nothing. Then by the time it sits for a while, when you start it, it may idle fine for a while, then just die out of nowhere...Restarts sometimes, sometimes not. Then when it does start, it will run for a little bit and die, whether at rev or at idle.


I am just about to drive this thing off a cliff. I am already in for $900 + and cannot just take it to the stealerhip at this point...they will charge 30 hours to find out what is wrong because it is intermittent.


sailor77 07-08-2007 10:01 PM

Dont feel too bad. I have a 96 that is doing the same thing. It is my moms and it will randomly stall at idle with in gear. Esspecially after sitting over night. It also feels, at random, like the cat converter is clogged and has no power.
Keep me posted and I will do the same for you

djdoug99 07-08-2007 11:01 PM


Originally Posted by sailor77
Dont feel too bad. I have a 96 that is doing the same thing. It is my moms and it will randomly stall at idle with in gear. Esspecially after sitting over night. It also feels, at random, like the cat converter is clogged and has no power.
Keep me posted and I will do the same for you

I just got a recall for 96 Jeep Grand Cherokee for the cat.


It says the PCM contains software that may not be capable of detecting a deteriorating catalyst.

If you have the 4.0 you might want to call your jeep dealer to see if you are eligible for this. If the cat is bad they give you a new one for FREE!

hawaii50 07-09-2007 05:45 PM

ECM / ECU issues
Great mechanic friend says he is certain it is the ECM (ECU) given the symptoms and that this item has sucked in Jeeps for years. I have seen $350 - $400 for the part. However, can anyone tell me if the part supplier pre-programs the VIN and odometer, does the dealer have to "unlock" any security stuff on the Jeep? I am told by the parts dealer that some cars require this.

Thanks again for input.

sailor77 07-09-2007 08:39 PM

I check with the dealer today and they had already done the ecm upgrade last OCT.
I am going to try a CPS tomorrow and let you know how it turns out

greasefingers 07-09-2007 08:46 PM

The PCM/ECU will have a bar code on it. Write down that number a get a direct replacement for that type. The number will identify all of the PCM inputs, and this is very important as a vehicle with a security system cannot be corrected for it if the PCM is not set up for one. In other words, a if your vehicle does not have a security system than you cannot use a PCM that is designed for one.

cher96 07-10-2007 01:22 PM

Runs then cuts out or diesels ?? ignition ?? help
I am having a simular problem with my 96 Cherokee. It either diesels or the ingition cuts off. It back fired twice. I only get 10 miles per gallon. I have replaced distributer cap, wires, coil, new plugs. Had 2 different shops put it on a cumputer. They both said it is running perfectly. After the second mechanic, I left and drove 2 miles down the road and it cut off. Walk back, ride with the mechanic to the Jeep and it is running fine. This has been happening for two months. It cut off 7 times coming back from town. This is my only vehicle and I have three children. Anyone who knows what could be wrong???????? Thanks.

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