OBDII codes on my 96 XJ, 6 of them... great!

I hooked up a scan tool to the XJ and got 7 codes. Starts from P0300, P0301, P0302, P0303, P0304, P0305, P0306.

I believe its engine misfire but what causes them in all the cylinders? Feedback greatly appreciated.

Its a 96 2wd sport.

boostamante said:

I believe its engine misfire but what causes them in all the cylinders? Feedback greatly appreciated.

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OK, backing up here for a moment: what symptoms led you to connect the code reader in the first place?

Miss fires on all cylinders= time for a new distributor. Old one has probably worn shaft/housing.

Wayne

casm said:

OK, backing up here for a moment: what symptoms led you to connect the code reader in the first place?

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Yes, need to know if symptoms (felt misfires) actually accompany the codes. If so, look for one "common" source.

If no symptoms, it could be that this is not real, but faulty signals somewhere (computer?) setting the OBD codes.

Well I'm not sure about symptoms per say, it just idles rough and has poor gas milage. I just recently purchased it so that's all I know. Other than that it runs fine.

plugs, wires, cap, and rotor-- clear codes and see if they return. Unless you know the condition of the routine maintainence items, you're just guessing.

boostamante said:

Well I'm not sure about symptoms per say, it just idles rough and has poor gas milage.

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Those would be symptoms.

I just recently purchased it so that's all I know. Other than that it runs fine.

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OK. As suggested, replace the spark plugs, distributor cap, rotor, and plug wires. While I agree that you may have a worn distributor shaft or bushing, start with the basics because even if you have to replace the distributor you'll still need to replace those items as well. If it's not the distributor itself, great - problem solved.

Also, just as a general statement: don't put too much faith in the code reader. Nine times out of ten they'll tell you what the symptom is, but not the root cause of the problem.

Ok how about P0300, P0303, P0306
Seems to run rough above 3k

Souske, same advice applies to your XJ.

P0300-random misfire
P0303-cylinder 3 misfire
P0306-cylinder 6 misfire

1. Gotta do that tuneup first. Plugs, wires, cap, rotor. Failing to do this might result in you chasing your tail.

2. If after that, you're still symptomatic/coding, test your fuel pressure (with a gauge) and compare your numbers to factory spec. Weak fuel pressure/volume can contribute to random misfires.

3. Fuel injectors a possibility although less likely. Good quality fuel injector cleaner (BG44K, Lucas, Techron) etc. never a bad idea to help optimize fuel injector spray pattern. Stay away from the el-cheapo fuel injector cleaner that lines the shelves of the stores; it's virtually worthless. Injectors can be swapped and see if the misfire follows to their new location.

Dammit Julio! your jeep gave my jeep a OBDVD!

souske said:

Dammit Julio! your jeep gave my jeep a OBDVD!

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I do not want any details on how that happened! :roflmao:

when there are big batches of error codes, they are usually chained off the first one