EKoS

I've recently noticed my motor making an unusual sound under heavy (though not generally WOT) acceleration - the best description I can come up with is that the volume of the exhaust note seems to "pulse" harmonically (louder/softer/louder/softer) between about 3 and 5k RPM or until I lift off the throttle.

I haven't thrown any CELs and don't actually notice any loss of power, but this one makes me scratch my head a bit. Any thoughts? Boost/timing variation, possibly, or a leaky valve or vacuum line? It could also be some sort of unusual resonance in my exhaust system, but I want to make sure I'm not about to blow something up...

ModifiedA4

this will tend to indicate if it is a drivetrain related noise or engine/exhaust.

JA4T

at first I thought maybe you were explaining a honking diverter valve. If you are sure it is the exhaust then I have a couple of suggestions. Check for broken exhaust hangers, check for leaks, check for faulty cat or resonator.
J

Justin517

at the engine.
ive read the 1.8T is an "inheriently loud" engine. how loud is too loud?
I its not realy audible from inside the car at all, and i dont have the sound deadening on the hood either (1997).
it dosent realy "tick" at idle, could i still ahve a valvetrain problem? my oil light dosent come on ever so im hoping it isnt low oil pressure.
I think its time to pull that valve cover off and snoop around a little, and this summer im going to drop the pan and replace the oil pump and pick up just because im paranoid like that.
Any thoughts?

JA4T

and that is because the crappy automatic. ugg. I think you need to take a look at things and make sure the cam chain tensioner is fine. Heck it may be time for you to get a new valve cover gasket anyway..I don't know. Good luck buddy.
J

CTA4AVANT

Sounds like a Wheel Bearing is going bad to me.