Boost won't affect the SAP pump, it takes air from the airbox and pumps it into the exhaust via the combi valve on the back of the cylinder head. That little silver thing on the back of the head is the combi valve. Taking the electrical connector off the pump will cause a check engine light but the noise should go away if thats it.

 

that is completely normal on the stock turbo mine does the same exact thinig

 

it can be connected to your bearings, steer car to the right and left and see which steer effects noise the most and you ll need to change the bearings on that side.. i had same issues and the noise was irritating as nothing.. sometimes you dont feel it because bearings sit in the right spot on higher speed or very low speed but it only happens around 45-60 kmph.. right?

 

I think that you are talking about wheel bearings? my noise is definatly not related to that. It noise is linked to the turbo some how. I still need to try to unplug secondary air pump. That makes more sence. (for my noise). If I start my car and drive off right away the noise will occur for the first 20 seconds of so. only The noise will only happen if the turbo is spooling. the noise will stop after that. If I turn off the engine and start it happens every time, hot or cold. I know that noise is not normal and does not sound good. thanks for your advise and time!! marc

 

Mine is just like that, only for the first couple psycles and only when the turbo is spooling. It seems to be getting louder as well...

 

today I unplugged my air pump and drove the car. the same noise was there. i have a lift and had someone power brake the car while i was under the car and heard the noise for a about 10 seconds. it seams like all the air hoses were vibrating. once the noise was gone the vibration was gone. it dont seem to misfire but almost like it is pinging heavily. (when you are right under the car it sounds different than when you drive). i always use premium fuel. i also only hear the noise when passenger side window is down. if any one can give advise i would love it!! thanks marc

 

There is no way you don't have any fault codes in the ECM. You scanned your car with a VAG COM?

 

Thanks for the PM. And no I have yet to VagCom it. Don't have one and not too stressed yet about it, plus super busy...

 

hi, no access to a vag. but i have a snap-on modus. no codes or any pending codes. heres some other info that i can give you. when i replaced turbo (thought due to noise) i used a new oem ko3 turbo and not a ebay one. i paid about $900 my cost. i also did not mind changing turbo due to the 80k i have on the car. after turbo was replaced i drove the car and the same noise was there. but..... the boost was very severe the car would lift up on take off. i drove the car across the parking lot many times and was amazed how much power this thing had. until i got a thumping noise from the right front wheel. found the axle was damaged. replaced both front shafts and noise was gone. soon after the check engine light came on. a over boost code was present. i looked over hoses make sure nothing was loose or not connected. everything was fine. i cleared the ses light. i had to drive the car home (due to time) about 20 miles. i did not accelerate to fast because i did not want damage engine or the shafts. i started the engine the next morning and everything was normal. no over boost or ses light nothing just normal??? i have not been able to conferm want caused that. i have put about 6k miles on turbo with no issues. just that noise. as you may be able to tell i change any parts that may be marginal. i probably over maintain this car but i dont like problems. i even changed all my coils with new after having one go. i carry spares in my trunk because one of the new coils all ready failed. cant trust it!! any suggestions please let me know. have been checking out new a4's but really dont want to spend the $ for one right now. have spent about 4k bucks into my car now its in perfect shape. other than that noise. thanks marc

 

^^^^^^^^
Well i think something was just blocking the wastegate or it was stuck for a short while
causing you to boost the turbo like all hell.
If you have already replaced the turbo, have you replaced the timing belt and water pump yet? Water pumps are another main cause of a clicking/knocking noise when the engine is cold.