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cylnder misfire?

E

etaniyani

NAXJA Forum User
Location
Santa Monica
hey all, i just got back from autozone to use their diagnostic computer to see why my engine light was on. also when i drove around and let the engine warm up, then stop and turn the car off, wait couple min and turn it back on the car would start shaking for couple seconds, the engine was running rough. just hooked up the comp. and it gave me 3 codes, P0300, P0301, P0303. it said misfire cylnder 1 and 3, multiple cylnder misfire. oh by the way its a 2001. any thoughts?
 
Pull the plugs on 1 & 3 and take a look at them.
 
the light came on while in mammoth 4 wheeling. for some reason every time we go up to the snow, the light goes on, then we get back down, the light goes away, but this time the light stayed. spark plugs are new, i replaced them when i got back. anything else i should start with. i was thinking it could be the cap that goes over the spark plugs. any other thoughts. thanks.
 
Plug wires, cap and rotor.

Bad vacume line somewhere?

Cleaned out the throttle body reciently?

I would start there since you have already done the spark plugs.

AARON
 
with the engine cold, start it up and have a spray bottle with water and a mist spray handy, when it starts to heat up spray each one of the runners on the exhaust manifold the ones that sizzle right away are firing the 1 that isn't is not firing all the way. this way you at least narowed it down to the exact one or 2 thats missing ( i never trust computers this method at least makes me feel comfortable beause i know for sure) you have to be careful not to let the engine get heated up to much other wise the heat transfer in the manifold will sizzle everywhere. i would then swap wires with 1 that is working and see what happens, if nothing changes pull the plugs and switch them so on and so forth
i just thought of something, i have only done this on v8's with easy access to headers but i think there is enough room between the heat shield to spray them not sure if this will work on an XJ
 
ya i know, i think 2000 they stopped using the distributor method and moved to something else. its a little harder to work on it this way. but i was thinking that the cap that goes over all the spark plugs maybe be bad. what doesn't make sense to me, is that the rough idling only occurs when the engine has already been running for a while and the temp is up, then shut it off. once i start it back up after couple min, this is when it idles rough.
 
oh they have a coil on plug ignition? $$$$$$$$
 
those are lot of dollar signs. does that sound like the problem? do you think i have to replace that whole cap? im going to talk to the cheif mechanic at jeep, see what he thinks about those codes, and possible solutions. keep the info coming, just no more dollar sings. thanks.
 
etaniyani said:
those are lot of dollar signs. does that sound like the problem? do you think i have to replace that whole cap? im going to talk to the cheif mechanic at jeep, see what he thinks about those codes, and possible solutions. keep the info coming, just no more dollar sings. thanks.
Click to expand...


no i actually dont have much experience with coil on plug i've just heard they aren't cheap, considering i'm used to a 40-50 dollar tune up i'm sure those lil majik boxes cost more than that, but lie i said i don't have much personal experiece on them just hear say. they could be cheap
 
"The Problem: With coil on plug systems starting to get older the spark plug boots and connector springs are starting to fail. Contact springs corrode and fall apart because of moisture buildup. Boots are also deteriorating and developing cracks and pinholes which allow arcing and intermittent misfire."

that seems like the problem. ill try that and see what happens. does anyone know if jeeps carries those parts? how about after market stores, 4 wheel parts, etc?
 
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another thing you can try is (assuming your working in a garage) turn off al the lights with the truck running see if you can see any sparks arcing across anywhere, f its dark enough you should be able to see it fairly easy
 
I had a cylinder missfire on piston #1 that was caused by a loose connection to the #1 fuel injector. The shop that ran the diagnostic put a ziptie on there to keep it snug. It has lasted fine for the past 5 years. Every once in a while I will snug it up some. You might check your fuel injector electronic connectors for these cylinders.
 
To you have the recall heatshield installed? If not, that may cure it. (

You could wrap the injectors with a heatshield/tape.

New boots for the coil rail (www.rockauto.com).

One of the above three got rid of my misfire issues, don't know which one though, did them all at once.

Less than $35 to do everything.

HTH
 
etaniyani said:
hey all, i just got back from autozone to use their diagnostic computer to see why my engine light was on. also when i drove around and let the engine warm up, then stop and turn the car off, wait couple min and turn it back on the car would start shaking for couple seconds, the engine was running rough. just hooked up the comp. and it gave me 3 codes, P0300, P0301, P0303. it said misfire cylnder 1 and 3, multiple cylnder misfire. oh by the way its a 2001. any thoughts?
Click to expand...

TSB 18-010-01. Needs a flash update for the cold weather issue, if you are out of warranty expect to pay 1 hr labor to have it done.

TSB 18-031-03 which as mentioned is for the hot soak restart and adding a insulator sleeve to the #3 injector.


Mike R
 
alrighty, got the problem all fixed up. bought a new coil, fixed the problem. i drove it around, to heat up, shut it off, waited couple min, and started again, testing to see if it would run rough but never did. drove it around rest of the day with no problems. wasn't too expensive at $142, i would of had to pay jeep $89 just to diagnose the engine light. so not too bad of a deal in the end thanks all who replied.
 
Oh forgot about another common issue that trips misfire codes on 00-up, the cam sensor/oil pump drive walking out of sync. Some early ones even had them seize up.


Mike R
 
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