# Misfire only in Cyl 5.



## AmIdYfReAk (Nov 8, 2006)

yeah, Another misfire thread. 

the car in question is an Audi A6 2.8 30V, i had the Seemingly common leaking valve cover gasket issue.

About a week after fixing that, The car started getting misfires and only in Cyl 5 according to Vac-com and its been getting progressively worse over the weeks.

Beyond the "normal" things that would cause this ( Oil in with the plug "shorting" out the wire to the head, bad plug, Bad wire ) Would anything Else be causing this?

I'm not looking at the coil pack to be the issue, Due to it being wasted spark I'd think that two cyls would be misfiring/dead if that was the issue, Am i correct in assuming that?

Thanks for any insight into this issue, i should have a vac-com output of the car by tonight.


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## O_o (Nov 12, 2009)

AmIdYfReAk said:


> Due to it being wasted spark I'd think that two cyls would be misfiring/dead if that was the issue, Am i correct in assuming that?


Pretty reasonable assumption. If memory serves, 2 & 5 fire together (and 1 & 6 and 3 & 4).


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## AmIdYfReAk (Nov 8, 2006)

O_o said:


> Pretty reasonable assumption. If memory serves, 2 & 5 fire together (and 1 & 6 and 3 & 4).


Thanks for the reply man!

Its a little hard to get time with the car due to it being someone elses daily driver, but i was able to get it for a few minutes today to be able to scan it, and this is what came up:



> VAG-COM Version: Release 409.1-S
> 
> Control Module Part Number: 3B0 907 551 BA
> Component and/or Version: 2.8L V6/5V G 0050
> ...


The SAI codes i think are due to the Controllers/valves at the top of the engine, I redid the Vacuum lines and i think they are routed incorrectly, but that's another thread/issue. 

Moreover, at one point i hope to have the car at the house, and test the spark and pull the spark plugs.


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## O_o (Nov 12, 2009)

SAI not working would explain the catalyst efficiency codes. Looks like you have a faulty wheel speed sensor or wiring as well though.

I don't remember how to do it, but there is a way you can log misfires with VAG-COM to confirm that it is actually misfiring, and you can drive it around to see under what conditions. My guess would be that the oil accumulation fouled the plug. Random misfire might be because of the SAI problem, causing a vacuum leak.


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## AmIdYfReAk (Nov 8, 2006)

i cant seem to connect to the ECU when the car is running, So logging is basically out of the question.

The SAI Codes are simple enough, When i get a little time and etc I'll check the vac-routing and make sure it was done correctly, that would get rid of those codes. 

yeah, a wheel sensor is gone, the car hit a curb on the front right side enough to bend the two lowers and break the speed sensor while it was at it. 

That is that neither this or that, its an issue for another day or care 

i've redone the vac lines, getting rid of the Cloth style ones with thick walled Rubber ones, i can assure you there is no vacuum leak on the motor, i feel as though i've routed the N112's on the top of the motor incorrectly causing the Combi valve's not to open with the SAI is on, nothing more. 

Thanks for the replies man


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## AmIdYfReAk (Nov 8, 2006)

One of the Hardlines going to the Combi was split in two. 

So i removed the vac source from the T fitting and capped it, Basically all of the Bucking went away but its still detecting misfires on mild acceleration.


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