Just today my CTT started to make a buzzing honking noise under hard acceleration only. This is after the coil packs and spark plugs were replaced at the dealer. My question is about the possible diverter failure and what that noise sounds like and what conditions bring out that issue? To my knowledge the DV’s have never been replaced and the car just went out of factory warranty with 36k miles (2005 CTT with FVD upgrades; computer, bypass pipes, lowering module).

 

I replaced the DV's with EVOMS DV's but still have the noise. Hoses looked fine so what else could it be?

 

The noise you described sounded like a Diverted Valve failed, but you are still getting that noise after you replaced the DV - I'd take it to the Porsche dealership.

 

this noise you describe sound similar to one Im experiencing with my 06' CTT.

My noise sounds like a "honking" noise and can be felt in the accel pedal and steering too. It happens only upon agressive acceleration from a stand still or from a rolling or slow speed. Once at higher speeds I cannot duplicate it.

Ive been thinking either DV's or possibly the front differential?

Did you ever track down the culprit of your noise?