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FIXITMAN
FIXITMAN, Master Technician
Category: Audi
Satisfied Customers: 17406
Experience:  ASE MASTER CERTIFICATION, AA DEGREE AUTOMOTIVE/DIESEL
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Audi A6 Quattro: 2.7t misfire when warm

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2.7t misfire when warm

FIXITMAN :

Hello, my name isXXXXX appreciate you taking the time to ask a question about your car. Can you tell me if you are getting a check engine light? How many miles are on the car?

Customer:

156k miles...CEL light flashes an code is a P0304....cylinder 4 misfire. I changed that coil, that plug, that injector...moved them to another cylinder, always #4. Runs good cold, when things are rich, then gets progressively worse as it warms up. Rough idle, hesitation when accelerating. Almost all issues are when RPM's are low and warm.

Customer:

Also have cleaned injectors, run premium fuel with octatane boost...maybe EGR valve or intake manifold leak? However I have sprayed two cans of carb cleaner and engine starter trying to find a leak. Also had a mechanic find one leak, which he fixed and said there were no more....what about 02 sensor?

FIXITMAN :

Thank you for the reply. If your code is isolated to one cylinder then it will not be an O2 sensor. It sounds like you might have an internal issue with that cylinder like carbon build up. I would start by running a compression test. This will let you know if there is a valve problem or another cylinder problem. Has this been done?

Customer:

haven't done that yet

FIXITMAN :

That is the next this that needs to be done. it is common for the valve seats to get beat up in this engine especially if a low grade of gas has been used. This would show a low compression reading.

Customer:

Thanks for the info...so I found the problem. There is good an bad information on the web. Just for fun, I thought I would double check which clyinder is #4. The original web page I went to was wrong. I had been working on the wrong cylinder this whole time. Put a new coil pack on the correct #4 and now it runs great.

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