Hi everybody,

Please take a little time for my rather long story, but consider the
fact that I' am struggling with this matter for more than a year.
I've bought a Audi TT, 1.8 Turbo, 225 HP from 2000, and soon I have
discovered that the turbine (turbocharger) is broken - was throwing
oil in the exhaust system and the effect was a black smoke.
I've changed the turbine, then because VAG-COM reported a error I've
changed the Lambda oxygen sensor everything was OK in respect with the
VAG-COM, or at least I got no more errors.

Then I have noticed ( I don't remember if this happend before I
changed the turbine) this strange behaviour: whenever I relase too
suddenly the throttle pedal I hear a noise in the air filter area
(some kind of rattling) and the engine rpm drop dangerously to a 400 -
600 rpm. Sometimes in slow speed corners the engine stops.

For this I have changed the throttle body with a new one, after many
calibrations and cleanings - no difference.

Recently I have changed the debitmeter with a new one and everything
got crazy. First the car worked almost as before - with a small lack
of power when I begun to press the acceleration pedal.
When I stoped after few kilometers I received the error:

Control Module Part Number:
 Component and/or Version: 1.8L R4/5VT         0001
          Software Coding: 05710
           Work Shop Code: WSC 00000
1 Fault Found:
16486 - Mass Air Flow Sensor (G70): Signal too Low
       P0102 - 35-00 - - - Intermittent

Then I cleared this error, made another few kilometers and I got:

Control Module Part Number:
 Component and/or Version: 1.8L R4/5VT         0001
          Software Coding: 05710
           Work Shop Code: WSC 00000
1 Fault Found:
16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
       P0130 - 35-10 - - - Intermittent

I cleared also this error, I have callibrated the throttle body and I
got again the Lambda error.
I have cleared again the Lambda error and then the car became not
stable when I started it. It didn't start at the first few tries, I
got a huge rpm variation, I got explosions in the exhaust etc...

I had to disconnect the debitmeter (pulled of the power cable) and the
car worked different in the sense that it was the first time I didn't
experienced rpm drops, although the noise in the air filter area was
still persistent. But,       I couldn't go over 3500 rpm - it was
clear that this was not the fix.

In the next morning I have connected the debitmeter back, got
difficulties when I tried to start the engine but I have hepled the
engine to start by pressing hard the throttle pedal. Whenever the
engine passes the first phase, with the acceleration help it goes to a
"normal" behaviour.

Because I got again the Lambda error I have put it out and clean it,
although it was allready clean. From then on I  received no more
Lambda errors.

I have drove the car, with a difficult start, but then it worked fine,
on the highway with 130 - 160 km/h. When I got off the highway, after
couple of kilometers with 40 - 100 km/h, the ESP warning on bord
lighted up. I have stoped and I have seen that I had the new error:

Control Module Part Number:
 Component and/or Version: 1.8L R4/5VT         0001
          Software Coding: 05710
           Work Shop Code: WSC 00000
1 Fault Found:
16487 - Mass Air Flow Sensor (G70): Signal too High
       P0103 - 35-10 - - - Intermittent

Even though I have cleared the error in the next 100 km it appeard
again a couple of times everytime announced by the ESP on bord.

I stoped, cleared the error, didn't start the car for few days then I
made around 300 KM - normal rode and highway. I had dificulties to
start the car but then it worked almost like before I changed the
debitmeter and ... I got no more errors! The next day, after a
difficult start I drove around 10 km but again no errors.

What I have noticed and I believe it is important is that whenever I
have dificulties to start the car, in the "001" Measuring Blocks field
in VAG-COM I got at "HOS2 Control" a constant "25%" value. Anytime
else I got a constant variation from -7% to +10%.

Well, that's the story... If it not clear please indicate me what else
should I do and what other data may I offer you. Maybe based on your
experience you can help me clarify:

- why the car is producing a rattling noise while decelerating in the
air filter area? I believe that it is relared with the "cut-off" valve
but how can I decide it is broken, what experiments should I make,
what data in VAG-COM should I follow?

- why is the rpm droping when I take the foot off the pedal?

- is the new debitmeter broken, or is the old one but in such manner
that it hides some of the car's vices?

- what do you think I should do to solve the problem or make it clear?