'02 S6 4.2 misfire

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05-11-2010, 05:08 PM

Slvrs6

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'02 S6 4.2 misfire

I have a little (see: "big") issue... I've spent about $ 2k diagnosing and repairing what I thought to be an issue with the drivetrain and/or suspension.

What I know? My car has a vibration under load. It was bad around 60-65 then in a period of days got very bad to the point where it felt like the wheels were going to fall off.

First time in the shop

Shop Notes:

Quote:

Originally Posted by Stealership

Verified Complaint. Found the right rear wheel bearing is faulty and causing a humming noise. The bank 1 catalyst is broken and is rattling. Both front upper rearmost control arms have torn inner bushings and are rubbing on the strut support. Both front inner CV boots are torn and the joints are loose. All of these could casue a vibration under load.

Replaced both front axles and both front upper rearmost control arms. Replaced rear wheel bearing.

I drove the car and after 3 minutes turned right around and headed back towards the shop. The suspension what tight - that feeling you get after replacing the control arms. Nice and snug up front. But under power, there was still a vibration that increased and decreased with power and gear. Sometimes it was there when compression braking down a hill, but not as bad

Second time in the shop

Shop Notes:

Quote:

Originally Posted by Stealership

Verified the vibration under load. Pretty much at any speed. Inspected transmission and axle area. Found excessive play at front differential right output shaft. Vibration appears to be coming from the trans area.

So I take the car to a transmission shop that has done plenty of work on Quattro Audis. After driving and putting it on "the rack" they don't see anything wrong with the car's transmission or front differential. They say the play in the right front is not excessive, but rather... normal and from what they can tell.. the only thing wrong with the car is a misfire.

lightbulb
2k miles ago on my 100k service they said I had a random all-cylinder misfire. I don't know the code, but should have it sometime tomorrow. I have a dead cat. Bingo right?!? Or not..

My question is.. would a misfire really cause a vibration to the point where it literally felt like the wheels were going to fall off (pre-suspension/axle work)???