What device decides a cylinder is miss firing...

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

Post by 32wildbilly » Thu Jan 10, 2019 6:00 am

Just a curiosity question: What is the circuit/device/sensor that detects and reports that a cylinder is miss firing?

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Dgi 07
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Re: What device decides a cylinder is miss firing...

Post by Dgi 07 » Thu Jan 10, 2019 6:27 am

Ultimately, its the ECM. Its looking at knock sensors, front and rear O2 sensors
Its figuring if the mixture was right, or wrong. If its wrong, it will lean it out or richen it up. If neither works, you get that marvelous little light on the dash that we all hate.
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Re: What device decides a cylinder is miss firing...

Post by b3freak » Thu Jan 10, 2019 6:51 am

32wildbilly wrote:
Thu Jan 10, 2019 6:00 am
Just a curiosity question: What is the circuit/device/sensor that detects and reports that a cylinder is miss firing?
Are you getting the dreaded blinking CEL? Or just curious? :)
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 » Thu Jan 10, 2019 7:21 am

b3freak wrote:
Thu Jan 10, 2019 6:51 am
32wildbilly wrote:
Thu Jan 10, 2019 6:00 am
Just a curiosity question: What is the circuit/device/sensor that detects and reports that a cylinder is miss firing?
Are you getting the dreaded blinking CEL? Or just curious? :)
No blinking just the steady light and the "Drive to Workshop" message. I checked the code and it indicates P0306 #6 misfire so coils and plugs(+ injectors because of all the hysteria about alcohol in fuels)here we come. Plugs are past due anyway as now at 55k miles. I had two transient short-term misfires over a couple of years when after being parked in garage in super rainy weather then driven. Funny thing was they self corrected and didn't leave a code. I should have just taken care of it then, but procrastination is a disease!

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

Post by 32wildbilly » Thu Jan 10, 2019 7:22 am

Dgi 07 wrote:
Thu Jan 10, 2019 6:27 am
Ultimately, its the ECM. Its looking at knock sensors, front and rear O2 sensors
Its figuring if the mixture was right, or wrong. If its wrong, it will lean it out or richen it up. If neither works, you get that marvelous little light on the dash that we all hate.
Thanks Dgi. Was wondering if it was something other than just O2 sensors. You answered my question.

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

Post by b3freak » Thu Jan 10, 2019 7:24 am

32wildbilly wrote:
Thu Jan 10, 2019 7:21 am
b3freak wrote:
Thu Jan 10, 2019 6:51 am


Are you getting the dreaded blinking CEL? Or just curious? :)
No blinking just the steady light and the "Drive to Workshop" message. I checked the code and it indicates P0306 #6 misfire so coils and plugs(+ injectors because of all the hysteria about alcohol in fuels)here we come. Plugs are past due anyway as now at 55k miles. I had two transient short-term misfires over a couple of years when after being parked in garage in super rainy weather then driven. Funny thing was they self corrected and didn't leave a code. I should have just taken care of it then, but procrastination is a disease!
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!
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 » Thu Jan 10, 2019 8:31 am

I do have a little ticking in the area of #6 and minor oil consumption so yeah I am aware of the possibilities. Plan to review plug conditions and drive it if not too alarming. If it gets bad will just toss an RND engine in and drive on...
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!
[/quote]

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

Post by b3freak » Thu Jan 10, 2019 8:38 am

32wildbilly wrote:
Thu Jan 10, 2019 8:31 am
I do have a little ticking in the area of #6 and minor oil consumption so yeah I am aware of the possibilities. Plan to review plug conditions and drive it if not too alarming. If it gets bad will just toss an RND engine in and drive on...

Go to YouTube and look at Jake Raby's video. He's examining a M96 out of a C4S.

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

Post by 32wildbilly » Thu Jan 10, 2019 8:47 am

b3freak wrote:
Thu Jan 10, 2019 8:38 am
32wildbilly wrote:
Thu Jan 10, 2019 8:31 am
I do have a little ticking in the area of #6 and minor oil consumption so yeah I am aware of the possibilities. Plan to review plug conditions and drive it if not too alarming. If it gets bad will just toss an RND engine in and drive on...

Go to YouTube and look at Jake Raby's video. He's examining a M96 out of a C4S.

Yep, saw it from your post on Renntech. Piss poor design if you ask me!

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

Post by b3freak » Thu Jan 10, 2019 8:52 am

32wildbilly wrote:
Thu Jan 10, 2019 8:47 am
b3freak wrote:
Thu Jan 10, 2019 8:38 am



Go to YouTube and look at Jake Raby's video. He's examining a M96 out of a C4S.

Yep, saw it from your post on Renntech. Piss poor design if you ask me!
Yea, unfortunately, Porsche really didn't solve a lot of the water cooled flat 6 problems until the 9A1 engine. But even Raby says it's still too early to know what problems will surface from the newer 9A1 engines. Tony Callas has recently posted several videos on the 996 Mezger turbo engine. You should check it out. Just when you think those engines are bullet proof, an expert like Callas presents another story.
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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