2013 Audi a6 V6 Supercharged misfire one whole bank 456

Daniel Owner New Jersey Posted   Latest  
Unsolved
Driveability
Runs Strong But Shakey Idle

Codes for misfire on one bank , short term and long term pid normal for one bank (close to zero) but neg 10-15 on other bank at idle) performed valve cleaning (pulled intake walnut blast) also replace breather box (had way too much vacuum in crankcase ) any thoughts out there everything seems to be in order and responsive o2 move as should, plenty of power customer states dealer replaced all 6 injectors less then a year ago.

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Albin Diagnostician
Washington
Albin
 

Have you tested for proper airflow through both cylinder banks? Your fuel trims sure look like one bank is constipated.

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Darren Mechanic
Wisconsin
Darren
 

What’s the best way to check airflow bank to bank?

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Glenn Owner/Technician
Texas
Glenn
 

I would venture to say a exhaust pressure transducer and a scope setup. autoditex​.​com/page/pressure….

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Glenn Owner/Technician
Texas
Glenn
 

A vacuum transducer could be used the same way. It just takes knowing how to apply the cursors on your scope. Air flow into and out of engine produces pulses that can be measured. A common hand held vacuum gauge is a basic reference tool and cannot record date in millisecond of time like a scope and transducer.

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Albin Diagnostician
Washington
Albin
 

Start with the fuel trims, then move on to a relative compression test, with a FLS hooked to the intake, then crank it for 20 seconds or so, Be sure to sync your scope to the ignition of cylinder #1

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John Diagnostician
Texas
John
 

I would be weary of that long of a crank. I recommend no more than 15 seconds to protect the starter but I feel safe with 10 seconds and wait to let the starter rest. if it’s timing itll Definitely show. intermittent sealing issue, its possible it might need a couple tried to reveal itself.

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Charles Technician
California
Charles
 

How many miles are on this? Did you do a compression test on all cylinder yet? Have you sprayed some brake clean around the lower intake area to see if you can find any vacuum leak? Compare your scan tool data for camshaft actual and specified readings from both banks

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Daniel Owner
New Jersey
Daniel
 

Miles 141000 , new upper and lower intake gaskets / new breather box/ decarbed valves/ reset adaptive , while driving bank 2 is -25 at times driving and idling hovers around -15 , bank 1 spot on 1/-1 only codes for 4, 5 and 6 misfire no loss of power at all , idles slightly rough ,

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Glenn Owner/Technician
Texas
Glenn
 

Hi Danial, This is pointing toward timing components on that bank The upper chain is likely out of time or the actuator has failed. An in cylinder pressure test with a transducer and scope would confirm this issue. You may be able to tell by doing a relative compression test, there is a 50/50 chance that would show this bank has issues. All the cylinder would show low for that bank. At this…

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Charles Technician
California
Charles
 

Because it is a varying reading between driving and idle it maybe just a broken guide or bad tensioner on bank 2. I would recommend you remove the upper timing cover on that side and look for broken guide pieces and press. The chain tensioner is oil dampened so it should slowly compress with constant pressure. If it goes in and out easily with no resistance it should be replaced. I have not…

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John Diagnostician
Texas
John
 

what In fuel management can cause negative trims only on one bank? If oxygen sensors are responsive I’d be suspect of the inability to properly exhale. test drive, graph oxygen sensors and 02s. Go up to WOT.

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Glenn Owner/Technician
Texas
Glenn
 

I recommend you do a back pressure test pre CAT on both banks. Check at idle and at 2500 RPM. If all shows good there then concentrate on the cams and crankshaft correlation. To have the issue on one bank of cylinders only, usually spells restriction or a cam timing issue. Look at cam phaser PID's if you have them on your scanner. A broken or stuck phaser is possible. The other possibility is…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Danial, I forgot to mention earlier, you need to reset the PCM an do a thorough test drive after the repairs you have done. This way the monitors can all start fresh. Sometimes PCM's think they see an issue because of history. You may have fixed it and the computer as not recognized it. If you have already done that, then ignore my suggestion.

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Louie Technician
New York
Louie
 

Hi Daniel I had the same issue on the same model entire bank 2 misfires .Turns out a rat crawled under the supercharger and chewed the ECM harness I replaced the harness car ran perfect after that.

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Tony Technician
California
Tony
 

I would start of doing a VE test to see which way it points your next test. Unstable fuel trims from one bank to another sounds like a timing issue or a restricted exhaust.

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Michael Technician
Indiana
Michael
 

Tony, I agree, timing issues cause compression variations and is easily shown with a simple relative compression test, Here is a picture of a late model ford v6 with a bad chain driven water pump. It had codes for timing and rich/lean(can't remember which) for one bank. Chains and pump corrected both. You can see that every other cyl. was high/low.

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Elon Owner/Technician
North Carolina
Elon
 

Check for a bad CAT on that bank.

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