Determination of misfiring

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metronet

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	Determination of misfiring « on: September 21, 2014, 10:41:10 AM »

I can't seem to find the answer by searching and so I decided to start my first topic here. Hope that is ok.

According to the system strategy doc misfire monitoring has two paths, within an interval of 1,000 or 200 crankshaft revolutions.

My questions are:

A. Is it normal to have single digit misfires in Misfire monitoring that are reset after each interval. Since it did not reach the threshold there are no DTC stored (or no MIL light flashing for Catalyst damage).

B. Can the sensitivity be adjusted/tuned and do these single digit (less than 10, not out of the blue moon but consistent) Misfires I have been having really impact the overall engine performance?

Engine is a ME7.1.1 3.0 AVK.

Thanks for reading.


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zillarob

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	Re: Determination of misfiring « Reply #1 on: September 21, 2014, 10:11:37 PM »

Unfortunately, sounds like par for the course on an avk.

Buddy had one that liked to misfire too.
Change the oil and it would run fine. I still dont know wtf was up with that.
He finally killed it (blew coolant hose and kept driving) so I put a 2.7 in. Problem solved Grin


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metronet

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	Re: Determination of misfiring « Reply #2 on: September 22, 2014, 01:56:04 PM »

Quote from: zillarob on September 21, 2014, 10:11:37 PM

so I put a 2.7 in. Problem solved Grin

lol... a 2.7 in a B6 that's awesome!

I am not giving up yet, the car drives great and no DTC codes so far (knock on wood). I will try to do some loggings and provide more information.

Thanks for the reply!


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Vdub-dub

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	Re: Determination of misfiring « Reply #3 on: October 03, 2014, 11:50:11 AM »

no misfire detection and no dtc's. have you tried logging lambda see if it lean issues when misfire happens?


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metronet

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	Re: Determination of misfiring « Reply #4 on: October 05, 2014, 12:39:29 PM »

Quote from: Vdub-dub on October 03, 2014, 11:50:11 AM

no misfire detection and no dtc's. have you tried logging lambda see if it lean issues when misfire happens?

Thanks Vdub-dub, I am attaching some log files that I logged today.

It seems like the misfires shown in VCDS are not showing up in ME7Logger...?

Are these correct values for logging ME7.1.1 misfires?

Code:


fzabgs_w
fzabg_w_0
fzabg_w_1
fzabg_w_2
fzabg_w_3
fzabg_w_4
fzabg_w_5


ECU identified with following data:
HWNumber    = 0261207794       (requested was 0261207794)
SWNumber    = 1037367215       (requested was 1037367215)
PartNumber  = 8E0909559E       (requested was 8E0909559E)
SWVersion   = 0004             (requested was 0004)
EngineId    = 3.0L V6/5V       (requested was 3.0L V6/5V)
VAGHWNumber = 8E0909059
ModelId     = G


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metronet

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	Re: Determination of misfiring « Reply #5 on: October 06, 2014, 08:44:53 PM »

Here is a graph shows single misfire from cylinder 6 at highway cruising speed.

It seems like it happened right after decelerating (see throttle plate angle).

Are these normal? Any suggestions on other values I should be looking at? Thanks!


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