Hi all,

Looking for some ideas about my 2001 vrs, just ticked over 96k miles.

In the last few days it has developed a noticeable roughness when the engine is between 2500 to 3000 rpm. Its a low-frequency vibration/harshness, audible and felt through the throttle pedal. It happens regardless of road speed/gear, just at these engine speeds.

I realise it could be one of any number of things, but just wondered if anything obvious jumps out as I am fairly new to these engines. Maybe indicative of a bigger problem if it is left to develop?

Probable coincidence but just fitted new fuel filter, thermostat & outside temperature has dropped suddenly.

Oil/plugs/filters all fresh, no codes and it still pulls as normal.

Hoping its nothing sinister as I've had to fit new brakes, bushes, timing belt etc. In the last few months!

Thanks in advance for any response

Edited 7 December, 201015 yr by Openwindow

bump

It might help if you take a sound clip and then it would be easier to identify....

This was on another website listing the diverter valve as a possible cause.

Early production vehicles had a Bosch bypass valve with the number ending in 108 or Audi 710A which due to problems would eventually be superceded by a Bosch 114 or Audi 710N. This valve was far better in performance but still not completely reliable especially under modified conditions.

MTM did extensive research on various bypass valves for their 400 -500HP kits and came up with the Bosch Sport Valve 110 being the best in performance and durability, even over more expensive aftermarket valves. At JHM we also tested various options and concur with MTM’s findings. With the Bosch Sport Valve the boost recovery and throttle response are enhanced significantly and since it is dimensionally the same as the original the installation is simple.

As stated in Audi’s technical bulletin dated Dec. 8, 2000 the bypass valves should be replaced should the following occur: “Groaning or howling noise from engine compartment when accelerating during partial load between 2500-3000 RPM,” or “ Rattling noise when decelerating between 2000-3000 RPM,” which “may be caused by the internal diaphragm of the charge pressure bypass valve producing pulsating noises.”

So, the short answer to your question is that a new DV (Bypass Valve) will avail you nothing if the one in your car is working properly. If you replace a faulty valve with a new and possibly better valve, your car will simply perform as it should. It isn't a performance modification, it's a maintanence item.

Thanks for the advice Ollie

Unfortunately since posting the car has become buried at the bottom of a snowbound hill and is going nowhere! Once liberated I will attempt to capture a sound clip, although it may be too subtle.

The symptoms in your post do sound like an identical match and as far as I know it still has the original dv.

Do you know if the 114/710N is suitable for the AUQ engine?

Cheers

Yes the 710n is suitable.

If your going to change the diverter valve I would probably go for a Forge 007p or a bailey DV30. Its a well documented fault and these are a lot more robust. Just depends if that's the problem.