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Old 02-16-2022, 09:21 AM
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Cylinder order: scanner numbering vs diagram in the manual. Different?

I've read that the cylinder number that a scanner displays may not follow the diagram posted. Something about how a scanner numbers the cylinders in firing order rather than the way the manual does. This may be completely wrong...it maybe be a fault of the scanner's compatibility with BMW. Not sure...just asking...

I haven't had this issue before with other vehicles, but I am having an issue diagnosing a cylinder misfire and thought that this may be the cause (maybe I replaced the wrong plug/coil)

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Old 02-25-2022, 01:18 PM
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what scanner...what manual...



dont assume a 'misfire' means 'that cylinder is the one misfiring'...also do not assume "misfire on X means 'repleace coil and plug on X'"... nor does it mean "if the coil and plug dont fix it, it must be the injector'
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Old 02-25-2022, 02:31 PM
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It was more of a question in general.

Do scanners all "map" the cylinders with the same numbers system? I suppose that would make sense because they are just reading the computer signals.
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Old 02-27-2022, 09:03 PM
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Im going to say all scanners call cylinder 1, cylinder 1. They may not present data in terms of "firing order". But a misfire on cylinder one is, say, "P0301"...hence whatever the hex/binary string the DME has output should be interpreted by ALL scanners as 'cylinder 1'. It is the DME in the car that detects a misfire, decides which cylinder was the culprit and then formats the error output....
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Old 02-28-2022, 12:06 AM
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Quote:
Originally Posted by Dante2004 View Post
I've read that the cylinder number that a scanner displays may not follow the diagram posted.
Possible. I was reading that in the INPA rough running values, sometimes the cylinder 'numbers' are actually representative of a firing order. But, when viewing the stored misfire code, the rough cylinder displayed was representative of the stored misfire code.

The N62 is a very complex engine with variable valve timing and valve lift. There's a few quagmires in that engine that usually leave techs spinning their heads.
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Old 02-28-2022, 02:50 PM
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Recognize that a 'misfire' is a guesstimate by the DME...


As the engine is spinning, the DME is reading the rotational acceleration of the crankshaft... (this is how you get the 'rough running' display from INPA, etc)


When one cylinder seems to 'lag' the expected motion, the DME says 'misfire on X'


On an engine with problems, that misfire can sometimes be attributed to the wrong cylinder. All these signals are coming into the DME to be decoded- crank position sensors, cam sensors, etc.



But this isnt what OP asked... A misfire on cylinder 1- so this is the cylinder the engineers are BMWAG decided will be 'cylinder 1 forever and ever' will ALWAYS be coded with a hex error code that attributes this to cylinder one. Different code readers CANNOT 'remap' this and say it is a different cylinder.


In terms of diagrams? Who knows...thats just a graphics exercise. Grab the BMW firing order from ISTA. Nothing else matters
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