Sam Hill

Hello everyone. I recently bought a used 2002 TT Quattro so I decided to join Audi World forums so that, hopefully, i can both learn about my car and provide info from my personal experience as well.
I have to admit however that as a result of never making an effort to learn about cars and how they work, I am not very mechanically (automotive mechanically) inclined, which brings me to my first question.


Can anybody tell me what this is? The guy I bought the car from had extremely broken english, but from what I understood, He had it installed and it makes a loud sound at high RPM along with serving some beneficial purpose. What I'm hoping for is that the loud sound i hear when i hard accelerate or change gears at high RPM is this mod and not the sound of my turbo charger aging poorly.

If accelerate really hard or change gears at high RPM it sounds like something is spinning on a loose or worn axis. Like a worn out, rattly electric motor spinning or something.

While driving normally though, The turbo sounds fine, or at least what I think is fine. With my windows down I can hear it kicking on and off when it's supposed to, no rattling whatsoever and not abnormally high pitched or whiny.

Does anyone know what could be making this sound?

lyleswk

I am pretty sure that is were the diverter valve is supposed to be. It may be a pop off valve which is not compatible with the engine unless you have changed the programming in the ECU. The sound some folks are trying to get is what you are hearing in the video below between shifts. Are there any identifiers on it like brand or part number?


Bally family, jump in here too...

SportMode81

Looks like a BOV. Google search blowoff valve. I have one too on mine but I have the HKS SSQ3 and modded it.

Sam Hill

Thank you guys. The sounds this mod is supposed to make are very similar to the ones I'm hearing.

The BOV that was installed in my TT has no markings. searching for it doesn't get me a make.

If the ECU is tuned to accommodate it I guess i could live with the noise. From what I've read though they aren't recommended for the TT because they cause the engine and turbo to "run rich". Consume more fuel? Work too hard? not sure what that means.

lyleswk

The perfect mixture is a stoichiometric mixture of 14.7 parts of air to 1 part of fuel. Running rich means there is too much fuel, which means fuel economy goes down, engine runs hotter locally (meaning in the cylinder head...would probably never see this in your coolant temp until the head lets go...), it will clog the catalyst quicker, you will have less power, etc, etc. If you have no idea what how the seller had the car setup, I would find a known DV /BOV and ECU tune and reconfigure the car.

Sam Hill

So what I've gathered is that my Audi uses a closed loop turbo system in which the excess pressure from the turbo must be "diverted" back into the system after passing through a sensor array rather than "blown off."

I'm a pretty big fan of efficiency so I think Ill replace this BOV with a good aftermaket DV.

Does anyone have any recommendations?

Sam Hill

Also, from what Iv'e researched about ECU tuning, it seems expensive. I wouldn't mind if I were upgrading intake, exhaust and tuning for performance but since I'm only putting in a new DV it would be cool if I didn't have to pay a few hundred.

Not sure how much different DVs vary in performance specifications or how much difference it would make to the turbo/engine in they did, but i wonder if it would be un-advisable it would be to put in the new DV and then reset the ECU to factory condition? I cant imagine it being more un-advisable than running a BOV on a car that has a closed loop turbo system.

Input is valuable here.

lyleswk

I am not a "modder", so if it were me, I would buy a OEM DV and find someone to flash ECU back to OEM. So, over to those on the forum that have experience with modding..