hesermon

I'm new here and did not realize I had posted this in Cherokee section instead of here, please offer up any help you may have, thanks!
1997 Gr. Cherokee 4.0 - all the classic symptoms. Random stalling, sometimes will start right back up, sometimes has to sit for 5 to 15 minutes. Once it starts it may run perfectly for 2 days or start backfiring, bucking, and dying within 2 minutes. Vehicle has has an engine transplant from a 2000 Gr. Cherokee (had same exact symptoms with old engine) ALSO, sometime alternator will charge at 14 volts then drop to 0, turn the key off then right back on, it starts charging again. Sometimes for hours, sometimes for seconds. Only code is P0351-Ignition Coil #1 primary circuit.
Tried so far, wiggling the PCM connectors (actually works sometimes), used PCM from junkyard (found one that had a rebuild date on it from 8/2011), new tps, new cps, new coil. Tried removing the screws from the PCM cover (read on a forum somewhere). Based on the size of the fireball that blew out the muffler, I don't think fuel is the issue, it has to be ignition.
The symptoms are exactly the same before and after the engine swap and with a second PCM. The engine is from a 2000 GrCherokee, the only sensor that did not match up was the oil sender was in a different location. I used my intake w/ throttle body. Since none of the sensors were swapped from one engine to the other (and I've replaced the TPS & CPS) I can't see it being anything but the harness or wiring. Is there a known failure or trouble prone area (I.e along the frame or near exhaust) that I can more likely find a problem? The connectors at the PCM have been cleaned, re-cleaned and cleaned again! All pins appear clean and straight. I'm puzzled???????

Has anyone found the magic cure for the random stalling that seems to be so common with these vehicles?

Bustedback

Sounds like a cam sensor issue to me.

KD3NE

Not sure which CPS you replaced ......

Cam Position Sensor
Crank Position Sensor

When I had random stalls, I changed the CPS that is behind the motor, on the bell housing, driver side.

They say it is a biotch to change, however I found that with an air powered 3/8" drive ratchet and extensions it was a 5 minute job.

After that no more random stalling!

CrazyMacaw

You seem to have answered your own question, if wiggling the connectors at the PCM sometimes cures it temporarily then that's a good indication either the connectors on the harness of the PCM or the PCM itself is having issues. The connector closest to the engine on the PCM carries the coil driver signal on cav07 and the CPS(crank) signal on cav08. The harness side female pins can get distorted and make poor contact. You could try the old wire-ties around the connector bit, I got about 4 months of trouble free driving using it, but the problem eventually came back. I eventually replaced the connector and haven't had a problem since.

hesermon

Not saying you're wrong, BUT today I took the connectors back off, cleaned with brake cleaner, double checked the pins again, reconnected the harness. Started right up, let it run for about 15 mins. Shut if off and went into the house for about 30 mins. Came back out, cranked about 15 seconds before it started, drove 1 mile, dead on the side of the road. Went out wiggled connectors, nothing. Towed home, swapped other computer back in (again), started right up and running perfectly. I cannot get the engine to die or even shudder by wiggling the connectors while it's running. I tried zip ties but had to cut them off to swap computers when it died and would not start. The two PCMs I have are the one that came with the Jeep and one from the junk yard. The one from the yard is a recent reman. I guess they both could be bad but both of them work from time to time and I hate to spend a couple hundred bucks to find out that another PCM is not the answer. When it's dead there is no spark from the coil, when it runs, it runs perfectly. Almost never anything but "all or nothing". I think my next step is to replace that part of the harness, maybe a broken connection inside the plastic connector????
Thanks for the input, much appreciated!
Hugh

hesermon

I changed the crank sensor in the bell housing. IS there a cam sensor, if so where? I thought with a distributor there was no cam sensor or am I just thinking like a GM guy?
Hugh

hesermon

CrazyMacaw, how did you replace the connector? The whole harness with new or junk yard (can't imagine I'd find a good one), or does Jeep sell a replacement connector? That is my next step, thanks!

Bustedback

The cam sensor is IN the distributor, it's also known as the pickup coil.

hesermon

I have never heard a pickup coil referred to as a cam sensor. I have not changed it because the problem happened both pre and post engine swap, it would have to been bad in both distributors.

CrazyMacaw

I found a replacement connector at my local dealer.
Apparently it had been sitting on the shelf a while and they were glad to be rid of it.
It retailed for $70 but I got it for about half that. The part number is 05014013AA



Another option is to buy new pins and replace the existing ones in the connector.
You'd need a small pin extractor tool to remove the old ones.

Pins - http://www.mouser.com/ProductDetail/...jBOZcRbVlrYA==
Extractor tools - http://www.summitracing.com/search/P...raction-Tools/

hesermon

CrazyMacaw.......Perfect! I will call the local dealer tomorrow, if I can't find one I'll get the pins and tool ordered. I am way more optimistic about this than any other idea that's been floated my way so far! I do appreciate all the ideas and advice given by everyone so far. I'll post my results.
Hugh

hesermon

I'm back, still no resolution. Changed the connector nearest the engine using the Jeep replacement connector, did not fix any of the symptoms. I'm completely out of ideas. It would already be at the crusher if not for the fact that I'm so hard-headed I can't stand being beaten. I may swallow my pride and drag it to the JY.....

96XJSE2DR

Were you able to get this fixed? Wife has 97 with same scenario and everything has been changed as discussed here and in many forums on the internet in regard to the 96 and 97 Grands except the PCM. (Saved it for last) Tommorow I am purchasing a reman PCM from Cardone via Oreillys. Not sure if its true or not but Cardone claims the Potting material used in the original PCM causes the chips to lift from the board causing the sporadic issues. Guess I will know in a couple days. Tired of big booms out exhaust and shut offs in the middle of intersections. Wife wont even drive it.

96XJSE2DR

97 Grand Cardone PCM Info:
"
Cardone Remanufactured - Engine Control Computer

Part Number: 79-4406

Line: A1

• 1 year limited warranty
• UPC: 82617457866

Detailed Description

• 100% resolder of critical components ensures superior electrical connections, no intermittent failures and longer product life.
• All modules are 100% computer tested to ensure reliable operation.
• On-car vehicle validation testing ensures that modules meet all fit, finish, functionality and durability requirements.

Brand Information



Features & Benefits:

• Defective OE conformal coating is removed from the entire ECM board, including underneath the chips, and is replaced with upgraded conformal coating. - Corrects an O.E. design flaw and ensures chips will not lift from the board, causing the unit to fail."

96XJSE2DR

Has been several weeks with Cardone Reman PCM from Orelllys and jeep is running great.
Did have to replace the IAC yesterday due to a low/rough idle issue as well as clean TB.