Audi 1.8T issues
 

My friend has a late model 1.8T engine in his car and lately he's lost acceleration and it sounds like the turbo is blowing air around, a blast of air comes up when he hits the accelerator and you're looking under the hood. My question is it conceivable for the car to have a disconnected turbo and still work, i.e. can a car that was never intended to be NA work as an NA?

sounds like a cracked hose. It happens often in those cars.

It depends on the location of the MAF in relation to the leak.

Let's say on a NA setup
If the MAF or whatever air flow meter it uses detects no air movement
(due to the air intake plumbing being disconected)

The engine should stall. Because the intake is no longer pulling air through the MAF.

However on a turbo setup.

the turbo itself can pull air through the MAF without the help of the intake.

So let me see if I can illustrate this in words.

You have inline the MAF then turbo then intake manifold.

If there is a disconnect between the turbo and intake manifold

The engine can run (poorly) The intake will get limited or no boost

(depending on the severity of the leak) As the enigne runs in "NA" mode

the turbo is spinning furiously trying to keep up to a certain boost level
(not a good scenario for the life of the turbo)

The pull from the turbo pulls air through the MAF and then engine will run.
Then engine runs poorly because the false MAF signal doesn't quite match
the need of the intake and injectors.

Hope this made some sense.

that certainly correlates with the sound of the turbo spooling up way too much and hearing and feelings large blasts of air

sounds like it could be the diverter valve. i was a previous owner to the audi v dub world and that is ussually the issue. the dv's go out in about 2-4 years depending on how you drive and your conditions. give that a try and it would be best for him to upgrade to a forge anyways. best of luck.

Diverter? I am not familiar with that terminology.

Are you refering to the Bypass/recirc/blow off valve,

or the wastegate,

or something entirely different?

But a bad BOV could cause the same symptoms.

Upgrades are the way to go! I love it when something oem breaks

and I can replace it with better/fast/cheaper (sometimes) parts.

Yea, the diverter valve (DV) is basically the bypass valve. VW/Audi insists on calling it a DV for some reason.

Do those engines have intercoolers? If so it may be something simple like a hose coming loose. That would explain a loss of power too.

They have small SMICs.

yup the diverter valve its the same as a the bov but it recirculates. i doubt its going to be your intercooler. the chances of that happening in my opinion being if it is stock is slim to none. if your actually hearing a sound during accel it would prob be a leak hard to say if its coming from the dV. but if you hear a sound almost like a rally cars blow off kinda like a flutter. then its definitly the dv. but i mean really no clue without seeing it. ive had some problems before with my 1.8 and it came to down to something as hitting the coil packs. well good luck.

BTW i just needed to throw this in DO NOT GET A BOV from personal experience. just causes your car to run rich as hell and i mean better then lean but rich as hell due to the MAF. you will see a kit that actually caps off the hole come out from the dv to y our intake. BAD BAD BAD. well not at first but in the long run BAD BAD BAD. excuse me for the way im saying it but i just don't want anyone else going trough the crap i had to go trough with my 1.8. well thats all good luck.

^
Agreed. Would be better to upgrade the stock DV with a Forge or Audi TT DV.