# 01 A4 2.8 Missfires on one bank



## SlickNic (Apr 19, 2011)

Bought an 01 Audi some time ago with a bad head gasket, turned out to not be the head gasket. The threads were not able to hold the torque procedure and were pulling out almost immediately upon torquing (has anyone else heard of this issue?).

Long story short I put in time-serts and reinstalled the head. I am now showing compression of 150+psi on both banks however the entire bank that I did the head job on is misfiring. When the car idles you can feel the misfires occasionally and the car will not rev above about 3k RPM if you hold the throttle to the floor but it does seem to hold the 3k RPM level. I have a code reader and am getting Random multiple misfire and each cylinder (1,2,3) listed as misfiring. I've changed the plugs which were pretty new when I got the car but they were still black one the misfiring side. The other side had the standard slight tan color in the center but looked fine. This leads me to believe that the misfire is being caused by severe over fueling? If not fueling then it should be something that only affects one bank which should eliminate spark on the 2.8 as I have 3 coil packs, and each runs a plug on each side.

Any help or thoughts would be greatly appreciated as I'm a bit stumped a this point.


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## tryin2vw (Dec 30, 2006)

Check the sparkplug wires to see if they are going to the right cylinders. The numbers are written on the coil. Also check for vacuum leaks.


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## SlickNic (Apr 19, 2011)

*update 1*

I thought the same thing and have checked the plug wires to the coils against the Bentley and the numbers on the head and coils. I've also pulled the plugs while the car was running and all verified spark.

Last night we pressurized cylinder three with the air compressor and slowly rotated it past TDC to verify that we didn't have the cam 180 degrees off. Air did come out of the exhaust when it was supposed to and the intake later. There where times when it was coming out of both but I'm sure there is a certain amount of overlap. We did the same test on cylinder 1 with the same results. And both heads show 150+ psi so I think that it's mechanically OK. I also think we've eliminated spark. Leaving only air and fuel as possible issues. 

I have not yet tested for vacuum leaks but will test for those either tonight or Friday night and post the results back. I have considered swapping injectors to see if somehow they were plugged from burning antifreeze and or oil when the head gasket went?

Thanks for the reply and suggestions!


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## O_o (Nov 12, 2009)

Blocked right side exhaust?


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## SlickNic (Apr 19, 2011)

Interesting, I wouldn't have thought of that one. I wouldn't have put a rag in that while it was out... Not sure how it could have been blocked. Is there a simple test other than unbolt the manifold to exhaust connection, running it with that short a pipe should blow anything out and show if there is excessive restriction.

Maybe the CAT is the issue, I'm not sure how far the PO drove the car with a head gasket out. Maybe burning the oil/anti-freeze killed the CAT?


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## SlickNic (Apr 19, 2011)

Maybe just pull the pre-CAT O2 on that side? Think that would provide enough flow for the test, assuming the exhaust were 100% blocked (guessing it wouldn't be quite that bad).


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## Zebers (Apr 26, 2011)

I am currently having the exact same problem on a 2000 Passat. Engine ATQ. Head was done on bank 2, timing set and reset and triple checked. Compression great. Reoccurring codes multi miss cyl 1, 2, 3, and cam sensor allocation bank 1. Rough idle, accelerates fine and smooths out with a bit of gas. Swapped cam sensors to try and isolate, no change. Any suggestions????


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## Zebers (Apr 26, 2011)

If it were restricted exhaust, you would think there'd be an downstream O2 code, or CAT efficiency code at this point


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## O_o (Nov 12, 2009)

If you're using the Bentley, there is a typo. The number of links between bank 1 and 2 on the cam chain is different. I can't remember whether it's bank 1 or 2 that the information is wrong for. I'll try and dig it up.


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