04 grand cherokee laredo misfire

mossyoaktj · 11-16-2010, 05:49 PM

mom 04 laredo. has the v8 and now cylinders 1,3,5,7 are misfiring. when this started happening she said the oil pressure dropped and the fuel gauge dropped. any ideas as to what would have the entire side misfiring

mossyoaktj · 11-16-2010, 05:54 PM

just got this message about the jeep

it was running, then gauge dropped to 0 then died, rattled like sumpwas pluged up, drained oil, put new plugs in now wont start just back fires, i think the lifters might be collapsed and not pumping back up, and exhaust is closed, it blows carbon out the exhust bad

flatlander757 · 11-16-2010, 08:15 PM

Have you inspected the wiring for the fuel injectors and the coil packs for the side with the misfires? Sounds like something happened to the wiring to cause only one whole side of the engine to run like crap. There's no way that every one of the lifters failed to pump up at once unless the whole head is just caked with sludge. They are VERY easy to pull the valve covers... I think the gaskets are even reusable.

It has a 4.7L right?

Tool Man · 11-16-2010, 09:09 PM

check the o2 wire is it touching the hedder? look real close i had this happen took a long time to find out what it was when it happened to me

My 2 Cents Good Luck

mossyoaktj · 11-16-2010, 10:41 PM

yes its the 4.7.

ill pass the info along i wont be home from japan for another 2 weeks.

thanks

keep em coming

blazerbrad · 11-17-2010, 09:28 AM

The "carbon" out of the exhaust is just black exhaust from running extremely rich from the one bank (cylinders 1, 3, 5, 7...these should be the driver's side bank). Really sounds like you have the fuel system working with the injectors putting gas in the cylinders but no ignition on that side. I looked through the wiring diagrams and I don't see a condition where broken wire would disable 1, 3, 5, 7 ignition coils only without affecting the other bank.

There is a chance the problem is not isolated to just the one side. The camshaft position sensor is kind of the nerve center of the fuel and ignition (acts like a distributor). I would check it (think it's on the passenger side front head). Always trace the wires for breaks and check the connectors first, then maybe try replacing it (they are only around $25.......and if it doesn't work take it back).

11-16-2010, 05:49 PM	#1
mossyoaktj Join Date: Apr 2008 Location: moscow,ohio Posts: 245	04 grand cherokee laredo misfire mom 04 laredo. has the v8 and now cylinders 1,3,5,7 are misfiring. when this started happening she said the oil pressure dropped and the fuel gauge dropped. any ideas as to what would have the entire side misfiring __________________ UNITED STATES MARINE 99 TJ, locked, long armed, creepy's

11-16-2010, 05:54 PM	#2
mossyoaktj Join Date: Apr 2008 Location: moscow,ohio Posts: 245	just got this message about the jeep it was running, then gauge dropped to 0 then died, rattled like sumpwas pluged up, drained oil, put new plugs in now wont start just back fires, i think the lifters might be collapsed and not pumping back up, and exhaust is closed, it blows carbon out the exhust bad __________________ UNITED STATES MARINE 99 TJ, locked, long armed, creepy's

11-16-2010, 10:41 PM	#5
mossyoaktj Join Date: Apr 2008 Location: moscow,ohio Posts: 245	yes its the 4.7. ill pass the info along i wont be home from japan for another 2 weeks. thanks keep em coming __________________ UNITED STATES MARINE 99 TJ, locked, long armed, creepy's

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11-16-2010, 08:15 PM	#3
flatlander757 Fartface extrordinair Join Date: Aug 2010 Location: West Carrollton Posts: 127	Have you inspected the wiring for the fuel injectors and the coil packs for the side with the misfires? Sounds like something happened to the wiring to cause only one whole side of the engine to run like crap. There's no way that every one of the lifters failed to pump up at once unless the whole head is just caked with sludge. They are VERY easy to pull the valve covers... I think the gaskets are even reusable. It has a 4.7L right?

11-16-2010, 09:09 PM	#4
Tool Man - CORE Member - Join Date: Oct 2010 Location: Ross Ohio Posts: 61	check the o2 wire is it touching the hedder? look real close i had this happen took a long time to find out what it was when it happened to me My 2 Cents Good Luck

11-17-2010, 09:28 AM	#6
blazerbrad - CORE Member - Join Date: Feb 2007 Posts: 831 Images: 6	The "carbon" out of the exhaust is just black exhaust from running extremely rich from the one bank (cylinders 1, 3, 5, 7...these should be the driver's side bank). Really sounds like you have the fuel system working with the injectors putting gas in the cylinders but no ignition on that side. I looked through the wiring diagrams and I don't see a condition where broken wire would disable 1, 3, 5, 7 ignition coils only without affecting the other bank. There is a chance the problem is not isolated to just the one side. The camshaft position sensor is kind of the nerve center of the fuel and ignition (acts like a distributor). I would check it (think it's on the passenger side front head). Always trace the wires for breaks and check the connectors first, then maybe try replacing it (they are only around $25.......and if it doesn't work take it back).