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MotorGround >> Diagnosis...


11/14/08 8:34 PM
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Moke
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I have a '94 Jeep Grand Cherokee Laredo, straight 6.

It has always run perfectly and smoothly. Suddenly out of the blue last night while pulling away from a light, I noticed hesitation. I turned down the radio and heard the engine hesitating, sputtering, missing, and even pre-igniting. I was barely able to continue with forward motion, so I put it in neutral to see if it would idle, and it idled fine. I revved it up while in neutral and it revs fine and smooth.

As soon as I put it back into drive and put the engine under load (like accelerating or going up a hill) it started to sputter and ping again. I put on my flashers and was able to barely limp it home this way. Down hills or otherwise under little load, the engine ran smooth. As soon as I had to go up an incline or otherwise load the motor, it would sputter and ping again, barely netting me forward progress.

This morning everything works fine, but I don't want to chance it failing again on open road far from home. The first things that came to mind were fuel filter, fuel pump, or coil failing under load. My distributor is tight and clean as is all of my wires.

What the hell? What say you?
11/14/08 10:13 PM
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LetsTalkItOut
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So would you say your problem occurs when going up hills? Have you ran it up a bit in straight line?
11/14/08 10:21 PM
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Moke
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It's not so much the hill or angle, but the motor being under load, like pulling away from a dead stop on an even surface.

I barely made it up the slight inclines last night, but as I got momentum going downhill (where there was no load and the engine ran fine), I sped up as much as possible to build momentum to make it up the next incline.

I dove it up a steep hill slowly this morning making the engine work hard and it ran fine...I hate intermittent problems.
11/17/08 5:59 PM
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Ponyboy
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Put the key in the ignition and turn it on three times quickly leaving the key in the on position.

so it goes key in.........on.........off......on....off.....on.

Count the flashes of the check engine light.

It will throw two digit flashes.

So two quick flashes followed by a single flash is code 21.....etc.
11/19/08 3:40 AM
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Moke
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Edited: 11/19/08 3:42 AM
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Oh man, that's cool. I'm going to try that, however, a friend came by and dropped off an OBD2 car reader. I can check and see if the reader's code matches the code when using the ignition method.

Also since then, I opened my distributor and found lots of little aluminum powdered shavings at the bottom inside. It looks like for whatever reason, the aluminum contacts had corroded and got powderized by the rotor. The rotor itself looks like it should be replaced, so I will get a new cap an rotor and hope that's all it was...I'll be doing the code reader tomorrow.
11/19/08 11:05 AM
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Ponyboy
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Your car is not obd2 and the connector is on the firewall on the passenger side rather than inside the car.
11/19/08 11:07 AM
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Moke
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Shitballs. Ignition it is...
11/19/08 10:58 PM
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Moke
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Code 5-5...
11/20/08 12:25 PM
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Ponyboy
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5-5 means everything ok......or the computer is not sophisticated to enough to find the trouble.

I would pull the crank angle sensor out of the block near the bellhousing and see if the end is covered in oil and metal shavings.

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