1999 passat 1.8L turbo - "hesitation" when accelorating

[Michelle86]

As above, i have a 1999 passat, 1.8L turbo, auto, approx. 92500 km. It has issues with acceloration. If i have to punch the gas, it stumbles badly and almost seems to want to back-fire. This is even worse when going uphill. It drives fine otherwise, however when i need to demand a little more, it stumbles so bad sometimes that the car seems to lurch. I have taken it to 3 different mechanics' and they cannot determine what the problem is. Finally took it to a dealership and they said a component in the turbo was jammed (the rod) and they were not able to "un-jam" it. That was causing the turbo to be "active" all the time... SO...I have recently changed the turbo (oil, oil filter and coolant included), the MAF, the pre/front O2 sensor, the fuel system seems to be good when we did a pressure check, as with the vacuum lines. I've "wiggled" the wires under the dash going to the vehicle computer. I've changed the air filter. I only use premium (94 octane) gas. And now i am at a loss.
I have an OBD scanner. Previous codes have been: P1555 - "turbocharger boost pressure control valve, upper limit exceeded"; P1196 - "O2S heater circuit bank 1 sensor 1 electrical malfunction"; P0103 - "mass or volume air flow circuit high input". I have been unable to produce additional codes, even though the problem persists...

Please, please!??!?!?!? Anything would help!!! I love my car, but lately i just want to drive it off a cliff!!!! If there's any questions anyone might have, i'm not very "car-smart" but i'll do my best to answer!
Many Thanks!

[martin1810]

I might help if you post your engine code. I would clear all fault codes and get a proper vag-com scan. OBD scanners are not very good and they are at their worst with early models.

[Michelle86]

Thank-you Martin1810,
Engine code is "AEB". I have cleared all the codes, though i have print-outs of all of them. This OBD scanner (model 3120) is all i have unless i want to pay $150 CAN to a dealership to use theirs. Thankyou for the advice though - i'll keep that under consideration when i scan my car with the OBD.

[martin1810]

It is possible your OBD scanner is giving you duff info. P1555 can be translated to 17963 throttle valve control fault. eg. - Voltage supply or earth for throttle valve potentiometer (G69) and sender for throttle valve positioner (G127) defective
- Open circuit in the signal wire for G69 and G127
- G69 and G127 defective
- Positioner mechanics or throttle valve tight or sticking
Try giving the throttle valve assembly a good clean. It might be just sticking.

[Michelle86]

Thankyou so much! I'll try that this weekend! Hopefully this will be the last fix for this problem!
How did you get that other code?

[martin1810]

The code comes from VW's own data. That's the problem with the early days of OBD. I can't guarantee I am correct but that code fits your symptoms and that's the code VW say you should have from that OBD code. good luck.