Question about 2004 Audi S4

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2004 audi s4

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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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?

Posted on Feb 21, 2009


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