Question about 2004 Audi S4

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2004 audi s4 b6

A bad catalic converter will make the car misfire on cylinder 1,or is suppost to misfire on all cylinder.and also rough idle and running rich!the mechanic said that coulbe a bad pistons or broken valve,because looks like the pistons wall is scratched.only 52000 miles.weird.

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Very weird, a bad cat should not make it mis-fire, if it is just one cylinder it is mis-firing on, its worth checking the coil pack for that cylinder

Posted on Feb 23, 2009


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Bad catalyc converter! audi s4 b6

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Feb 27, 2009 | 2004 Audi S4

1 Answer

2004 audi s4

the car might still be under warranty. if you bought it as a certified used car they add on 25,000 miles to the existing 50,000 miles. If cylinder 1 is coming up misfire and your mechanic sees something wrong in that cylinder there most likely is some truth because if the cylinder was not firing right (detonating and discharging raw fuel) this would blow out the catalytic converter. The best way to see if it is a bent or broken valve is to buy a leak down tester which is part of a compression test. basically depending on specs you crank engine over grounding coils and see if all cylinders put out the same compression within 10psi of each other. it is usually around 160 -200 psi per cylinder. now to do a leak down test just leave pressure in and see rate of decreasing pressure and compare to other cylinders. if everything checks out i dont believe to be anything wrong with cylinder. Oh i forgot to ask any check engine lights on besides a cylinder 1 misfire P0301?

Feb 21, 2009 | 2004 Audi S4

1 Answer

2004 audi s4 b6

you would need to tell me more, to vague;;for a problem of this magnatude i or us would need more information ;;ie how did you come to the conculsion that its misfireing on number 1 cyclinder???.before we take this any further.i want you to do one thing;;; run a can of fuel cleaner through the fuel system lets say 100 kms.if this does not elemanate it. then come back to us .we need more details about number 1 cyclinder.????.and who said your power unit was missing on number 1;; add why????.adrian

Feb 19, 2009 | 2005 Audi S4

2 Answers

Rough idle,misfire cilinder 1.and the mechanic said that is something wrong inside the engine because he checked everything. coil,spark plug, fuel injector, and nothing.probably the pistons or valve...

volkswagen has similar problem , turned out to be intake air sensor near air filter box has 4 or 5 wires on the connector , but check with dealer for recall on this problem before you shell out any more $

Feb 19, 2009 | 2005 Audi S4

2 Answers

I have a 2005 audi S4 B6. I just bought it with 37,000 mile on it. I just got it on the road and me and a buddy were beating on it. when driving hard the oil pressure light would go on but then turn back...

Sorry for the bad news i have for you, sounds like you dropped pressure to the top end which would mean that the Hydraulic lifters one or more have failed, could be that your intake or exhaust valve may made contact with the pistons at TDC. In any case oil pressure problems are known with that car, we found that one of the ckeck valves in the short block may cause that problem.
Solution would be new Motor at about $15000 with $4000 core unless warranty will cover. make sure you do not have an intake or exhaust system on the car cause they will not cover anything. Other option is to spend about $10000 to do a complete overhaul. First check your oil filter and see if you can see any metal shavings. But according to what you have written i would not longer drive or start the car. Sorry bud, i think your motor is done!!

Dec 13, 2008 | 2005 Audi S4

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