# Mode 6 misfire data



## Bigplanz (Apr 10, 2009)

I think I found the answer to my question. 163 is not a misfire count. It is a raw number used to calculate a percentage of misfires over 1000 engine cycles. Multiply 163 X 0.0015 and you get the percentage of misfires. 0.245% in my case. 1 to 3% set a Type B code (MIL on steady). Over 4% misfire sets a Type A code (MIL, on blinking). Blinking means the Cat will be damaged so get the car fixed NOW.

Since my percentage is below 1%, no code set. Interesting stuff!


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## Brainbucket (Mar 30, 2015)

AND Blinking means the problem is happing now. :vs_cool:


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## Bigplanz (Apr 10, 2009)

More than 30% misfires (dead miss, like if a COP goes bad), computer shuts the fuel injector off to prevent severe Cat/engine damage.


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## Brainbucket (Mar 30, 2015)

Bigplanz said:


> More than 30% misfires (dead miss, like if a COP goes bad), computer shuts the fuel injector off to prevent severe Cat/engine damage.


On that vehicle, but not all of the manufactures do that.:vs_cool:


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## ron45 (Feb 25, 2014)

sensor.?


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## Bigplanz (Apr 10, 2009)

ron45 said:


> sensor.?


My understanding is that there is no specific sensor for this. It is an inferred value from crank rotation. The crank sensor tells the PCM what cylinder it it adjacent to, the time between cylinders should be equal, if they are firing. If one or more isn't, the PCM records the delay. Enough delays, it gets logged as a misfire. Most are cylinder specific, though random misfire will also trigger a light.

Mode 6 is raw data. Multiply the raw number to get misfire percentage per 1000 engine revolutions. Helpful for a slight miss that doesn't trigger a light. V8 engines can run smooth with a tiny miss. I have never noticed mine. 4 banger, different story.


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