What device decides a cylinder is miss firing...

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b3freak
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Re: What device decides a cylinder is miss firing...

Post by b3freak » Sat Jan 12, 2019 7:05 am

Dr_Strangelove wrote:
Fri Jan 11, 2019 12:13 pm
Timely and Topical - a nice combination.

https://jalopnik.com/mugen-has-made-the ... 1831677108
I bet the same guy designed Shogun Warriors! :D
2002 Porsche 996 Carrera - bare bones basic, but still a blast to drive! Heck, I don't even have PSM on it. Ha!

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32wildbilly
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Re: What device decides a cylinder is miss firing...

Post by 32wildbilly » Tue Jan 15, 2019 7:03 am

b3freak wrote:
Thu Jan 10, 2019 7:24 am
Cracked coil packs. I'm in the same boat. My car has the original coil packs and with all the wet weather, I'm getting random misfires too. Not trying to push the hysteria, but you may want to bore scope cylinder #6. Just to see the health of the motor. Cylinder #6 is the devil!
Why is the worse culprit usually #6?

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b3freak
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Re: What device decides a cylinder is miss firing...

Post by b3freak » Tue Jan 15, 2019 8:55 am

32wildbilly wrote:
Tue Jan 15, 2019 7:03 am
b3freak wrote:
Thu Jan 10, 2019 7:24 am
Cracked coil packs. I'm in the same boat. My car has the original coil packs and with all the wet weather, I'm getting random misfires too. Not trying to push the hysteria, but you may want to bore scope cylinder #6. Just to see the health of the motor. Cylinder #6 is the devil!
Why is the worse culprit usually #6?
I'm just basing it on the many reports from owners on the forums that describe that the problem(s) (e.g. scoring) usually reside within Cylinder #6. I believe Jake Raby said on (the other forum) that he is planning to do a new video on the topic of bore scoring for his YouTube "Rennvision" channel. Apparently, problems associated with scoring on M96/M97 engines have increased as our motors age. If it ain't one thing it's another! :(
2002 Porsche 996 Carrera - bare bones basic, but still a blast to drive! Heck, I don't even have PSM on it. Ha!

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gnat
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Re: What device decides a cylinder is miss firing...

Post by gnat » Tue Jan 15, 2019 9:01 am

32wildbilly wrote:
Tue Jan 15, 2019 7:03 am
b3freak wrote:
Thu Jan 10, 2019 7:24 am
Cracked coil packs. I'm in the same boat. My car has the original coil packs and with all the wet weather, I'm getting random misfires too. Not trying to push the hysteria, but you may want to bore scope cylinder #6. Just to see the health of the motor. Cylinder #6 is the devil!
Why is the worse culprit usually #6?
I don't recall the specifics, but I remember Jake wrote up a detailed explanation of it. Something about the side it is on, it's position, and how oiling works as I recall.

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b3freak
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Re: What device decides a cylinder is miss firing...

Post by b3freak » Tue Jan 15, 2019 9:09 am

gnat wrote:
Tue Jan 15, 2019 9:01 am
32wildbilly wrote:
Tue Jan 15, 2019 7:03 am


Why is the worse culprit usually #6?
I don't recall the specifics, but I remember Jake wrote up a detailed explanation of it. Something about the side it is on, it's position, and how oiling works as I recall.
Don't quote me, but I also think the heat/cold cycles play a factor. In other words, the pistons expand faster than the cylinder bore. You add extremely tight clearances and then you have scrubbing. After the piston begins to scrub on the cylinder wall, the iron skirt coating begins to flake off making the piston even more abrasive to the bore thus causing the deep scores. Tick Tick Tick BOOOOOOOOOM!
2002 Porsche 996 Carrera - bare bones basic, but still a blast to drive! Heck, I don't even have PSM on it. Ha!

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gnat
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Re: What device decides a cylinder is miss firing...

Post by gnat » Tue Jan 15, 2019 9:22 am

b3freak wrote:
Tue Jan 15, 2019 9:09 am
gnat wrote:
Tue Jan 15, 2019 9:01 am

I don't recall the specifics, but I remember Jake wrote up a detailed explanation of it. Something about the side it is on, it's position, and how oiling works as I recall.
Don't quote me, but I also think the heat/cold cycles play a factor. In other words, the pistons expand faster than the cylinder bore. You add extremely tight clearances and then you have scrubbing. After the piston begins to scrub on the cylinder wall, the iron skirt coating begins to flake off making the piston even more abrasive to the bore thus causing the deep scores. Tick Tick Tick BOOOOOOOOOM!
Yeah that's the gist of the scoring itself, but Jake had details about why #6 is the worst of the bunch.

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Re: What device decides a cylinder is miss firing...

Post by b3freak » Tue Jan 15, 2019 9:30 am

gnat wrote:
Tue Jan 15, 2019 9:22 am
b3freak wrote:
Tue Jan 15, 2019 9:09 am


Don't quote me, but I also think the heat/cold cycles play a factor. In other words, the pistons expand faster than the cylinder bore. You add extremely tight clearances and then you have scrubbing. After the piston begins to scrub on the cylinder wall, the iron skirt coating begins to flake off making the piston even more abrasive to the bore thus causing the deep scores. Tick Tick Tick BOOOOOOOOOM!
Yeah that's the gist of the scoring itself, but Jake had details about why #6 is the worst of the bunch.
yea, guess we'll have to wait for his new videos on the subject unless you know of the link that you're referring to. Thanks!
2002 Porsche 996 Carrera - bare bones basic, but still a blast to drive! Heck, I don't even have PSM on it. Ha!

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gnat
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Re: What device decides a cylinder is miss firing...

Post by gnat » Tue Jan 15, 2019 9:39 am

Hmmm.. A curated l lists of all his posts where he shared gory details of the m96 could be a very nice thing...

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Re: What device decides a cylinder is miss firing...

Post by MattBurns » Sat Jan 19, 2019 7:38 pm

To answer the original question of what device decides a cylinder is misfiring, the answer is the crankshaft position sensor. A misfire will slow down the pulses the crank sensor looks at. Since there is a missing tooth on cylinder 1 to tell the CKP where TDC is for cylinder one, it can determine from where the pulse is slowed down which cylinder is misfiring, unless there is more than one cylinder misfiring in which case the ECM will throw a P0300 random misfire code.

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