Turbo noise and type - looking for some help
Hi folks - Looking for some help. I have had a 1997 A4 1.9 Tdi 110 quattro for about three months even though it is 6 years old. Only has 49,000 miles on it, but in the rev band 1500-2500rpm in every gear whether engine hot or cold there is a very apparent turbo grinding or spinning noise which concerns me. I have driven other Tdi cars of the same year, both 2 and 4 wheel drive, and their turbo sound is very slight and hardly noticeable. I took it to my Audi dealer, they agreed there is a noise and checked out the impeller shaft for imbalance, it was OK. An independant guy at an ECU remapping place thought it might be the EGR Exhaust Gs Recirculation valve, but clamping the pipe to stop flow made no difference to the spinning/grinding noise. It does seem to vibrate alot though. He thinks it is maybe rpm harmonic dependant and said I should go back to the dealer. The noise stops once I accelerate through the 2500rpm turbo range and into the power range of the engine. Anybody else hear this on their car at all?
Did the older 1.9 Tdi 110bhp A4 have variable turbine geometry or was it only on the 2.5 Tdi. I have heard that it may have a Garrett GT-15 or VTN or VNT wastegate turbocharger. Can anyone throw some light on this?
Anyone know if the older quattro tdi has more fuel feed or different torque curve within the ECU to compensate for heavier weight over the 2 wheel drive model?