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Unread 04-07-2009, 07:30 PM   #1
timofthejeep
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03 Liberty 3.7L random misfire FIXED!

Well, here is my story. It all started 4 months ago. engine light and misfire. I did all the obvious, coils, plugs, computer, cleaned injectors, no help. I fought the thing all winter. Problem would come and go. Random misfires (p0300, P030x, P035x), the codes listed at times 12 different codes. They would come and go. The problem would move around. I started getting desperate. The battery was weak, so I changed it thinking it would cause a weak spark. Checked fuel pressure. It was OK. Vacuum leaks. Fixed them all. Nothing helped. Then the other night I was reading the Haynes manual in a completely different section... It mentioned the one thing that I had missed. (read on...)

It was late, so I called it quits for the night. I went to the shower smelling like I has spilled the gas can on myself. I was so frusterated. I know I am not that smart, but I AM smarter than a danged car... I thought to myself. So I started thinking about it. What could cause a random problem that comes and goes? It has to be something COMMON to all the COILS. I started thinking about how the voltage gets to the coils to cause the spark. Battery positive to fuse to ASD relay to coil positive to PMC to ground... what??? ASD RELAY?!?!? Here is the ONE THING that is common to all coils, and if it is weak or the contact is worn can cause a weak spark by not supplying enough power to the coils... It is not mentioned as an integral part of the ignition circuit. It is not out in the open where it tcan be easily seen. Out of sight out of mind. So I changed it. The misfire immediately went away. Within 2 hours the light went out. It has more power than it had in ages. Mileage better, too (thanks to the fixed vaccuum leaks no doubt.). CHEAP FIX that costed me a small fortune!!! ASD relay in the engine compartment fuse box. Tell all your friends!!! ASD RELAY!!!!


Last edited by timofthejeep; 04-07-2009 at 07:47 PM.. Reason: accidentally deleted needed information in orig post
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Unread 04-07-2009, 09:35 PM   #2
DaveJKJ
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Thanks for posting that info. There has been a couple of threads about that problem.
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Unread 04-08-2009, 08:42 AM   #3
asax08037
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The same thing happened to me. The bad ASD also caused 3 of my coils to go bad.
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Unread 04-08-2009, 11:51 AM   #4
richd
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Good Job,great information.
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Unread 04-25-2009, 07:43 PM   #5
timofthejeep
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Something else about this- When you work the coils over, put a dab of silicone dielectric grease on each connector and on the spark plug end of the coil. Do all six at the same time. Takes about 30 minutes. You can get the grease at most parts stores. Zone gives it away in little pouches they keep under the counter. Clean all corrosion from the connectors and pins before you put the grease on.
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Unread 04-27-2009, 07:13 PM   #6
timofthejeep
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Follow up-
Problem came back. There is a Chrysler Technote on this. It says to disconnect the AC compressor plug. If the problem goes away replace the AC compressor. I'm not sure what the AC has to do with the ignition, but who am I to say? My problem was where I broke the wire in the #1 cyl coil plug from pulling on it so much and it was intermittent. I replaced the connector by splicing a new one onto the old harness. I got the plug from a salvage yard where they cut it off with a little pigtail but a dealer can order a harness repair kit that has the plug, pigtails, and heatshrink tube in the kit about 30 bucks each Mopar Part Number 05019952AA. You need six kits for all 6 cyls. Once again, use the tune up grease. Good luck!
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Unread 04-28-2009, 10:36 AM   #7
N8FIS
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"replace the AC compressor" Bull crap! Maybe just maybe the AC clutch
coil but NOT the compressor!
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Unread 04-28-2009, 04:52 PM   #8
timofthejeep
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Well I know that. My guess is the coil has a ground fault or partial short that might cause the misfire. It's a sanden compressor, so a clutch should be readily available. Just takes a few special tools to get it off. Besides, replacing the whole compressor means breaking the system open, new filter drier, vac the system, new freon and oil, and a complete pain in the ... So no, I would not change the compressor, just the clutch. The tech note is just what the dealer told me. I've seen weirder problems. Anyway, jeep ran like a dream today. No CEL, no misses, smooth idle, lots of power, runs like new.
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Unread 04-28-2009, 04:56 PM   #9
DaveJKJ
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Quote:
Originally Posted by timofthejeep View Post
Follow up-
Problem came back. There is a Chrysler Technote on this. It says to disconnect the AC compressor plug. If the problem goes away replace the AC compressor. I'm not sure what the AC has to do with the ignition, but who am I to say? My problem was where I broke the wire in the #1 cyl coil plug from pulling on it so much and it was intermittent. I replaced the connector by splicing a new one onto the old harness. I got the plug from a salvage yard where they cut it off with a little pigtail but a dealer can order a harness repair kit that has the plug, pigtails, and heatshrink tube in the kit about 30 bucks each Mopar Part Number 05019952AA. You need six kits for all 6 cyls. Once again, use the tune up grease. Good luck!
Can you explain in more detail. Had a 03 KJ with the a/c compressor break and he had misfire codes P0305 and P0306 afterward ........replaced the condensor and changed plugs #5 and 6 and so far so good. The codes have not come back yet. This was 2 weeks ago.

I am real curious.
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Unread 04-28-2009, 05:21 PM   #10
timofthejeep
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I really don't know WHY the AC compressor could cause a misfire code. On mine the compressor plug is mounted on top of the compressor on a bracket. Just unplug it and secure it so it doesnt get into the belt. It befuddles me that the compressor clutch would cause a misfire. Just guessing that if it is shorted and grounding or if there is a damper diode built into the clutch goes bad or something like that it might cause a surge or spike in the wiring harness get back to the PCM. The dealer guy didn't explain the idea behind the note, he just read it to me off the computer screen. If my problem comes back I will check the AC idea, but I am inclined to think my problem was all the stuff I mentioned earlier. Believe it or not, the silicone tune up grease cleared 2 of the 3 codes I had toward the end of my fight with the thing.
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Unread 12-07-2012, 06:00 PM   #11
Redleg1seven
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thanks

I recently bought my 2004 Liberty from a dealer in Ohio and took it home to Rhode Island, well I had to register it and get it inspected (ohio doesn't inspect), so I get all good to go right and bam there's a major issue, the engine light is on, guy won't pass it with it on. So he gives me the run down of the computer stuff, longer story shorter, I'm trying this ASD relay, if this works you just saved this broke mofo a ton of money I can't and don't have to spend. THANK YOU so very much!!!! I can see this site is gonna be very helpful as I grow into my Liberty.
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Unread 12-08-2012, 04:44 AM   #12
Billwill
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Quote:
Originally Posted by Redleg1seven View Post
I recently bought my 2004 Liberty from a dealer in Ohio and took it home to Rhode Island, well I had to register it and get it inspected (ohio doesn't inspect), so I get all good to go right and bam there's a major issue, the engine light is on, guy won't pass it with it on. So he gives me the run down of the computer stuff, longer story shorter, I'm trying this ASD relay, if this works you just saved this broke mofo a ton of money I can't and don't have to spend. THANK YOU so very much!!!! I can see this site is gonna be very helpful as I grow into my Liberty.
You need to get the codes read out to see what is causing the engine light to be on......replacing the ASD relay is really a wild stab in the dark!

Please start a new post regarding your problem and let us know how things are progressing
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Unread 06-04-2013, 08:43 AM   #13
Rwms411
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I want to throw in my two cents...

After a complete engine rebuild 700 miles ago (due to the dreaded #2 intake valve seat drop) I decided to run some injector cleaner thru the fuel system. I had been planning to do it since the rebuild, but just never got around to it. Anyway, after putting in the cleaner and running 10 miles, the engine started missing and threw a P0306 code.

I swapped number 6 coil pack with number 1 just to see if it would throw one for the number 1 cylinder.

Once warmed up again, it ran just as bad, misfiring again and threw another #6. After about 25 miles, it began to smooth out and has been fine since.

My guess is that the misfire was due to some dislodged trash in the injector from the cleaner...
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