I hope someone can help. I have a 2000 b5 a4 with the 1.8t engine. When I rev the engine past 3500 rpm I hear a whining noise coming from the center of the engine. It only happens when the car is moving and at a lower rpm when the car is on a large hill. I recently changed all the belts, the diverter valve, turbo and all of the vacuum lines. I have no idea what it could be. The mods I have are an APR chip and Apr hoses. If I switch the chip to stock program the noise appears after 5000 rpm.

Any suggestions?

 

So this noise only occurs when the engine is under a load? Do you have a boost gauge? A quick guess would be boost leak, make sure all your turbo/intercooler hoses are tight.

 

I oddly enough have the same sound, only at 0pounds of boost and not vacuum. Can't quite figure where the hell it is coming from, i can hold the sound when i hear it on a steady ride right on zero boost. PITA

 

I have checked and all of my hoses seem tight. Sadly, no boost gauge. If I get on the throttle there is a slight stutter in the car. Would small leaks in the intercooler hoses cause that noise? If so, I will change the intercdooler hoses and see what happens.

 

If an intercooler/turbo-related hose clamp isn't tight enough it could cause certain noises. Things like this can often pop up when chipped.

Did you ever replace your diverter valve when you went with APR? That could also cause a leak, but I'm not sure what that leak would sound like. It could also be a random breather hose or check valve. A boost gauge is a very worthwhile investment!

 

+1 well worth investment.

 

I put in a 710n diverter. I have changed all of the vacuum lines and those check valves. I am thinking of ordering the SAMCO intercooler hoses unless someone has a different recommendation. I should invest in a boost gauge. My car is so mild, I just didn't think it was worth doing.

 

Even when stock a boost gauge is a good idea... can help diagnose a variety of problems, including this one!

 

At idle my vac is at 20 and while coasting from higher speeds it is right around 25-30 or so...seem normal?

 

That's right.