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  #1  
Old November 30th, 2017, 10:25
anthrax323 anthrax323 is offline
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Disabling individual cylinders on a 2001?

Hey guys,

Does the PCM on the 2001 XJ support any OBD2 mode 8 functions? I'm trying to pin down which cylinder is noisy (it's a bad rod bearing, wrist pin, or broken skirt... not sure which yet) and can't just pull a single plug wire since it has the coil rail.

Would disconnecting the injector accomplish the same task, more or less?
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  #2  
Old November 30th, 2017, 16:29
blakews2217 blakews2217 is offline
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Disabling individual cylinders on a 2001?

Quote:
Originally Posted by anthrax323 View Post
Hey guys,

Does the PCM on the 2001 XJ support any OBD2 mode 8 functions? I'm trying to pin down which cylinder is noisy (it's a bad rod bearing, wrist pin, or broken skirt... not sure which yet) and can't just pull a single plug wire since it has the coil rail.

Would disconnecting the injector accomplish the same task, more or less?


It would. Your taking one of the things away that it needs. ( fuel, spark and air. Your taking fuel). But it will throw a code for open injector circuit.


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  #3  
Old November 30th, 2017, 22:16
lawsoncl lawsoncl is offline
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Re: Disabling individual cylinders on a 2001?

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Originally Posted by blakews2217 View Post
It would. Your taking one of the things away that it needs. ( fuel, spark and air. Your taking fuel). But it will throw a code for open injector circuit.


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Instead of pumping unburnt fuel into the exhaust, you'll be pumping fresh air, so may see different associated lean/rich codes get set.
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  #4  
Old December 2nd, 2017, 10:43
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Saudade Saudade is offline
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Re: Disabling individual cylinders on a 2001?

Yes it will.

Or you can use a long blade screwdriver. Press the tip against the engine and your ear to the handle. This will magnify the noise. Move the screwdriver around until the noise is the loudest.

You will also hear all sorts of other noise so don't be too alarmed.
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  #5  
Old December 3rd, 2017, 10:29
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Greenz Greenz is offline
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Re: Disabling individual cylinders on a 2001?

Quote:
Originally Posted by anthrax323 View Post
Hey guys,

Does the PCM on the 2001 XJ support any OBD2 mode 8 functions? I'm trying to pin down which cylinder is noisy (it's a bad rod bearing, wrist pin, or broken skirt... not sure which yet) and can't just pull a single plug wire since it has the coil rail.

Would disconnecting the injector accomplish the same task, more or less?
Why not just drop the oil pan and look? Knowing the offending cylinder number doesn't fix the noise until the engine is opened anyways.

I'm asking out of curiosity for my lack of wisdom on this one.
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  #6  
Old December 3rd, 2017, 13:44
anthrax323 anthrax323 is offline
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Re: Disabling individual cylinders on a 2001?

Yeah... I was just beating around the bush.

Dropped the oil pan...



Hello there, piston skirt. A little pissed off now. Looks like I'm building a stroker.
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  #7  
Old December 3rd, 2017, 18:55
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Greenz Greenz is offline
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Re: Disabling individual cylinders on a 2001?

Glad you found it. One of my fears as well.

Once repaired, that stroker should be lots of fun.
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  #8  
Old December 3rd, 2017, 19:10
anthrax323 anthrax323 is offline
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Re: Disabling individual cylinders on a 2001?

It's an unmistakable sound. A lot like rod bearing noise, but way louder and more clacky.
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Old December 4th, 2017, 11:00
blakews2217 blakews2217 is offline
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Disabling individual cylinders on a 2001?

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Originally Posted by anthrax323 View Post
It's an unmistakable sound. A lot like rod bearing noise, but way louder and more clacky.


I can tell you what it sounds like when a 0331 head really does damage. I bought a 2000 xj with really bad rod knock. Pulled it and opened it and found a missing piston in a million pices in the pan and the rod just hammering away in the cylinder. My best guess is this

Ran hot, cracked the head

The crack opened far enough to allow water in from the coolant passage during the downstroke of the piston and filled the cylinder with coolant.

Piston starts to move up but water can’t go back fast enough through the crack. Piston hits it max pressure it can withstand and breaks around the rod and falls.

Piston pices and lots of water hit the hot oil pan

Gets sold for 800 bucks to me


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Old December 4th, 2017, 11:39
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Greenz Greenz is offline
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Re: Disabling individual cylinders on a 2001?

My sons Prism just broke a piston rod and then pushed it through the bottom of the oil pan puking oil and metal bits. That was cyl #4, Cyl #1 was full of oil fouling the plug. The darned car still runs on two cylinders but makes a whale of a noise. We laughed so hard over that poor little car trying to live. LOL!
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  #11  
Old December 4th, 2017, 14:07
blakews2217 blakews2217 is offline
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Disabling individual cylinders on a 2001?

My buddy bought a 94 v6 dakota to learn stick in. We were going to his moms ( we’re 18/19 years old) and right as I turned the corner it threw a rod through the pan. We drove it back across town to my house and proceeded to try to kill it. It ran for a few more days till it ate a big handful of floor dry. Fun times.


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  #12  
Old December 5th, 2017, 22:30
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BCKNBLK BCKNBLK is offline
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Re: Disabling individual cylinders on a 2001?

Hey Anthrax, just went through your situation myself, mine was the number 6 piston skirt. Rebuilt the entire engine (but not stroked) and went with a hotter cam. All quality parts this time, not like the original junk. It should outlast the vehicle now, runs really great. If you need any advice, help, hints, pointers, etc, let me know while this is all still fresh in my grey matter.
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  #13  
Old December 6th, 2017, 17:25
anthrax323 anthrax323 is offline
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Re: Disabling individual cylinders on a 2001?

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Originally Posted by BCKNBLK View Post
Hey Anthrax, just went through your situation myself, mine was the number 6 piston skirt. Rebuilt the entire engine (but not stroked) and went with a hotter cam. All quality parts this time, not like the original junk. It should outlast the vehicle now, runs really great. If you need any advice, help, hints, pointers, etc, let me know while this is all still fresh in my grey matter.
Thanks man, much appreciated! I'm tearing it down now and getting ready to figure out my plan of attack. I'm documenting it here since I'm already running into some weirdness:

http://naxja.org/forum/showthread.php?t=1145305
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