Hoping someone else on here has experienced the same problem, which has so far stumped the dealership and 2 euro-oriented independent shops.

2002 A4 1.8T Quattro, 180k miles

There’s a clunking noise and pulsating entire car shuttering, almost like the car is coughing, only under these conditions:
· The car is in drive.
· The car is coasting in drive, or applying minimum acceleration to maintain a speed.
· The car is hot (has been driven more than 30ish miles on the highway).

Check out this video of what it sounds like:

This condition is worst when going downhill and when turning left. I get a fairly consistent clunk every 1-2 seconds when at its worst. It doesn’t appear to be speed related but more load force related (doesn’t happen under acceleration).

If I’m doing a lot of highway driving, it’s very pronounced. If I haven’t been on the highway for several days, it’ll go away completely. It also doesn’t happen if the car is coasting in neutral.

I’m unable to recreate the noise by driving tight circles at a slow speed in either direction.

Having replaced spark plugs, coils, fuel injectors, engine wiring harness, air filter, fuel pump, fuel sending unit, fuel filter, and cleaned MAF – it does seem the car vibrates more than it should at idle and in gear.

I jacked up all 4 wheels individually and confirmed the ball joints, control arms, tie rod ends, brakes, and steering rack are all tight and with the exception of steering components, are fairly new. Put the car in neutral and spun the wheels, but am unsure if the noise the front wheels make is normal.

Check it out in this video:

I’m hoping to narrow the causes down before I go sinking money into drivetrain parts. It seems like these symptoms match up with some others have had with a bad center bearing.

One of the indy shops wants to replace the driveshaft ($2,800ish) and suggested the problem may be in the front diff/trans and need a replacement ($6,500ish – not gonna happen). Twice previously they looked over the car and suspension and said everything is okay. They originally diagnosed this problem as a vacuum leak and plugged catalytic converter.

Dealership looked over the car and says the drive shaft, axles, and suspension are all good after they replaced motor mounts.