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2003 Jeep Grand Cherokee Bucking at interstate speeds

I have a 2003 Jeep Grand Cherokee that misfires really bad when certain conditions exsist. I know that if I accelerate going up a steep hill - the motor misfires so bad that it is like a bucking horse.

The dealer called my 1st Jeep a lemon and replaced it, after numerous attempts to fix the problem, and now the 2nd Jeep does the SAME EXACT THING.

My dealership tells me that Jeep Hot Line doesn't have any reports about this problem from anyone else. My dealership is going to put a co-pilot on my Jeep to get better computer codes. All they know is that there is a misfire.

The 1st Jeep did this 3 times beginning at 3,000 miles until 10,000 miles when I got swapped it out for a different Jeep. This 2nd Jeep was brand new as well and at 23,000 miles at the same exact location as one of the previous misfires, it started misfiring. Most recently I was going 55 mph about 100 miles from home on my way to a relative's house. The first Jeep did the exact same thing at the same place. The car had different types of gas in it at various misfires so I don't think the problem is fuel related.

I was going up a hill on the interstate trying to pass a semi and when it kicked into passing gear -bingo, it started misfiring so bad I had to pull over.

After turning off the Jeep for about 15 minutes, the Jeep started and ran smoothly but the check engine light was on.

It does not matter if it is cold or warm out. It does not matter if I have gone 1 mile or 100 miles - the only consistent thing that I can find is that both vehicles are 2003 Jeep Grand Cherokees and that I was either accelerating or on a highway at highway speeds.

Thanks so much for advise and help.

Pat

Reply to
Pat
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Fairly sure the lemon laws don't have exlusions for getting a second one.

Sounds like a good idea.

Is this the 4.7 HO engine, or some other one?

? If you take your foot off, does it recover as soon as RPM drops?

Would think that would either be ignition timing or not enough fuel. Or crappy gas, but will make the possibly mistaken assumption that you've already tested this by filling up with premium from a different brand or two.

Reply to
L0nD0t.$t0we11

Hi Pat, I had the same problem with my 93GC and when the fule pump was changed the problem went away. My Jeep dealer had a bulletin on bad fule pumps that checked out OK but when they run for a short time there pressure dropped off and the bucking started. Ask your dealer to check his papers on fule pump problems. Mine had a bunch. George-NY

Reply to
George-NY

Lack of fuel would be high on my list of suspects as well. May want to post your problem over on the rec.autos.makers.jeep+willys where the Jeep mechanics hang out. Someone will likely have the TSB number if there is one.

Reply to
L0nD0t.$t0we11

WOW - what great suggestions. My Jeep has a 6 cyclinder engine. With the 1st Jeep that was called a lemon for the same problems, the dealership had reset the magentic pickup and later replaced it. I have used various gasolines and I don't think it is the quality of fuel. I usually buy from places that do a lot of business so that gas isn't setting around in tank. On the 2nd Jeep they cleaned the combusion chamber. I'm meeting with the dealership today. I want to review everything that has happened. While they can't figure it out - I have found at least one other person that had the same exact situation. (Their dealer couldn't find the problem either.)

This problem only seems to occur at about 55 mph and at least 2 times (1 time with each Jeep) have been as I was accelerating going up a hill. Once the Jeep kicks into the "bucking" mode - it will quit bucking if you let up on the gas but as soon as you need to acclerate, the bucking starts again. If I pull over, turn off the Jeep, wait about 15 minutes, it runs fine but the check engine light is on.

Reply to
Pat

Roughly 1/30/04 06:03, Pat's monkeys randomly typed: Someone will likely have the TSB number if there is one.

Make *sure* you mention your engine when you ask for help.

The I-6 Jeep tends to be extremely reliable and free from tick-you-offisms. Got one myself. The crank position sensor seems to be about the only thing that bothers them much.

Could swear that someone on the jeep group mentioned a fuel pump quality issue for the newer WJ's... which would make sense as the fuel pump contains the pressure regulator and check valve. And your symptoms sound pretty much exactly like something is having difficulty maintaining fuel pressure.

Ya may want to see if a different dealer is aware of the problem instead of waiting until it sets a trouble code. Had a different vehicle get a fussy fuel pump and it cooked the catalyst on a long trip.

Reply to
L0nD0t.$t0we11

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