alem

Hi all,

I have the following issue with my Audi 2.7T.

In last 6 weeks car feels very heavy on take off and there is a hissing noise coming from the engine when I accelerate but I can only hear it with the window is up. I checked the car for boost leaks with the smoke pressure tester and there are no leaks, also there are no error codes on the vag com.
My fan belt needs replacing as it occasionally squeaks.
Could it be the case that the hissing noise is from the fan belt as it only happens when the car is under load and that the lack of power is down to MAF.

Any help and suggestions would be greatly appreciated.

Alem

09mehashaw

What's your mileage?
Have you had the timing belt done?
Manual or Automatic?
The car weighs 4200lbs mate. It's not light.
The hissing noise does sound like a boost leak.
Check the Throttle Body Boot

You're Diverter Vavles are potentially broken.
Test Your Diverter Valve

alem

Hi,

Thanks for yor reply.

The car has 134K. The timing belt was done about a year ago. It's well withing the time frame for changing so I doubt it's anything to do with that.

The car is automatic and I have done full service on the tranny recently so it can't be that either.

I have done the boost leak test and it's perfect no leaks at all.

There are no error codes stored either.

I'm really confused and don't really know where to go from here.

The only thinkg that would make sense to me is that the noise is coming from drive belt and lack of power is down to bad MAF.

Alem

09mehashaw

You might be getting a crap ton of blow by from the turbos.
Take off one of your inlet pipes leading to the Throttle Body Boot and check for a large amount of oil.
Also, whilst doing that, check the TBB for tears.
I'm assuming you are still on stock turboes? They are a bit old now.
Also, the MAF sensor does get a bit dirty so maybe take that off and carefully clean it.
Check your PCV (Pressure Control Valve) to see if it's leaky as well.

amadorj

I had a similar problem (but didn't hear the hissing). Just no power when I hit the gas (felt like a flat 6 cyl car). Took to a local mechanic and they did a smoke test. The Y-Intake (plastic tube) apparently was cracked on the bottom and so it was sucking in all kinds of air plus they mechanic said it was throwing all kinds of unusual codes. He replaced the plastic Y unit and it works great again. The Power is back! Hope this helps.

Prospeeder

Sounds exactly like a boost leak. The hiss is the boost escaping through a loose clamp on a coupling, torn boost hose, cracked intercooler. Stuff like that.