so ive got two grand cherokees a 99 and 02.. i just bought the 02 this weekend. it wasnt running when i bought it. threw a code 1391 along with 0358 which are asd and #8 coil. the asd relay was bad so i stuck a new one in it and it started and ran well enough to get it home. no problems from the asd in a 30 mile drive. still get 0358 and it runs a little rough on acceleration. swapped out a coil from my other jeep and put a new plug in the #8, cleared the code, no change... still rough, code returned. took a quick look at the connectors on the coil and pcm but didnt notice damage. could a crank sensor cause #8 only to misfire or is it the pcm? i removed the pcm to attempt to find a problem within because i got a strong whiff of fried electronics. (gel incased, not attempting pcm repairs) i noticed the coil i took out stunk as well as the pcm. the coil was for sure bad because i put it in my other jeep and caused it to misfire also. so.... the coil was bad but a new one didnt fix it. the coil and pcm wreaked of burnt electronics or ruptured capacitor or something... so is a crank sensor possible or do i need to look into bad wiring or toasted pcm?? i want to think the pcm driver fried which fried the coil but the asd relay fuse being blown gives me mixed thoughts.. help

 

JC, blown caps have somewhat of a fishy odor. Doesn't seem likely to me that a bad PCM would cause only #8 to misfire. Scour the wiring for an open ground or a bad wire. Also check the wiring on the injectors. A bad injector would give you a #8 only misfire. By the things you are finding it does seem to be electrical in nature..........unfortunately they can be some of the toughest problems to rectify.

Also are you certain with the other coil, that it is actually a misfire condition? Are you smelling unburned/partially burned fuel entering the cats? Could this also be what your smelling and not electronics burning up?

 

thanks for the reply.. im almost certain its not fuel im smelling.. pretty certain its hot electrical and there is definately a misfire you can feel at idle and stronger during acceleration. i noticed either fuel or heavy condensation dripping from the exhaust that doesnt happen with my healthy jeep. i dont get a fuel smell under the hood tho. i researched the problem and found ONE case where someone had a similar problem and ended up being the pcm. of course its the only thing i cant swap from my other jeep to know for sure... wiring? ugh.. all the exposed wires look ok around number 8 and pcm everything inbetween looks ok as far as the protective covers not being melted or damaged.. id rather rebuild the motor than trace down bad wires.. not any sure signs of damage tho. im gonna swap the crank sensor tomorrow just for fun i guess.. i may swap number 8 and 6 injectors n see what that does. i thought a bad injector would throw a different code... ?

 

i also noticed when i replaced the coil, erased the codes, then started it up, i noticed right away it didnt fix anything so i shut it off and a few minutes later took the coil back out to check and replace the plug and the coil was to hot to hold after probably less than a minute of the engine running. didnt have the burnt electrics smell but didnt seem normal to me...

 

JC, after checking some tech data, and keep in mind i am not really a Mopar expert but indeed the PCM could be bad and cause just the #8 misfire. Keep this in mind though, the PCM doesn't fry other components when it goes bad, bad wiring fries components and bad wiring can fry PCM's. I only say that because of the burning electric/electronics you are smelling and the excessively hot coil. If it came down to it and you replaced the pcm, you wouldn't want the same condition to come back because of bad wiring so check everything out good and pcm should be last resort.

The P0358 code doesn't necessarily point to the coil itself, it merely points to circuitry involving the #8 coil. Just guessing by the excessively hot coil, I would say that you are getting power to the coil at times when you're not supposed to have power or it's likely being powered all the time. In this case it causes almost an advanced timing issue with maybe some knocking or pinging on acceleration. And because you don't have the P0308 code (misfire), I would guess that a true misfire condition does not exist. Again, leading me to believe (and its only my humble opinion) there is a wiring issue.

Also, I am confused as I read through your original post. You mentioned that you replaced the asd because of a 1391 code. The 1391 code is the crank sensor code. Blown asd relay would also make me suspicious of wiring issues.

 

it was a 1389 not 1391 for the asd.. sorry.. and it does throw a 0308 but it takes more than just a start up for that one to show up. the drive home did reveal that code. i guess im going to throw a crank sensor in just in case since i have a spare one. then strip the wire covers off everything between the coil and pcm and have a better look.. i understand the concept of a pcm not being able to damage a coil but couldnt a damaged coil effect the pcm? maybe the coil went bad and the previous owner ignored it, pcm got hot and took out the asd.. hopefullly didnt melt any wires in the process. i did noticed the smell wasnt as bad once i got the bad coil out of there. but it was stong again coming from the pcm harness when i unplugged it. thanks for your help. guess ill give the wiring a closer look.. ill keep you posted what i find today.

 

well, thought i was going to change the cps just for good measure. got the bolt out, wires disconnected, i fought it for two hours trying just to pull it out of the block.. still didnt get it out before i had to get ready for some family stuff.. try again tomorrow. as much prying and pulling as ive done im sure it needs replaced now. its loose and turns but will not come out.

 

well, spent 4 hours attempting to remove the cps without breaking it. well... it broke off.. out with the motor

may be a few months before i get back to this topic.. i dont have the time to mess with that big of a project right now.

 

did some research and apparently this happens a lot. you can raise the motor and access it thru the oil pan or drill a hole in the fender well and use a drill extension to drill a hole in the sensor, put a screw in it and wrap bail wire around the screw and jerk it out which sounds the easiest.. ill try that next weekend.

 

thanks for your input fish.. and for the next guy with a problem like this...

my trick worked for getting the cps out, had to use a grinding stone afterward to carve the rust out and change the oil but.. got a new one back in.. didnt fix it. didnt figure it would. got the pcm today after work and had it running perfect in 15 mins.. no codes.. wheeew. pcm $241 at autozone comes preprogramed ready for plug and play. my guess is the coil went bad and burnt out the #8 coil driver, blowing the asd relay in the process... all good now

 

Glad to hear you got the sensor out JC. I have never heard of a COP burning up a PCM. These Chrysler built Jeeps are truly unique beasts. I hope everything you did solved your problems.