SEAT Alhambra TDi (sudden loss of power)

Ive had a new, SEAT Alhambra 1.9 TDi (the higher rated one) for about 10 months now, and keep getting a sudden drop in power / acceleration when trying to get to a high speed or on travelling at a high speed.
Ive no engine experience but Im getting no success from the dealer - its been in three times now - and Im pretty sure hes just fiddling with the fuel mix!.
Once the problem has occurred the revs go right up - with little peddle pressure, until I entirely stop the acceleration, and from around 120km/h, it switches back to normal again.
This can be quite a shock, and dangerous - with complete loss of speed when pulling out of a slip road onto motorway / autobahn.
Since I need to speak to the dealer in German - Id like to have a better idea of the problem (otherwise I get the feeling he is just brushing me off!).
Any help - or suggestions appreciated.
P.S. it is under warranty.

1. Go to a different dealer.

2. Is the car "self accelerating"?

If yes, then,

There are only two things that I can think off

a: Faulty accelerator potentiometer. When you press the accelerator pedal, the accelerator potentiometer translates the movement of the accelerator pedal into an electrical signal, which is feeds into the management computer. If this is faulty, or the power supply to it, then I can see that the car migh somethimes refuse to accelerate, or another time accelerate more than you want. It has limit switches, so that the ECU knows when you are not pressing the accelerator at all, or when you are pressing it all the way (maximum), but inbetween (partially pressed) it uses somesort of resistor (like a carbon track?) and wiper. If that is bad then you might get erratic results. Or maybe it is loose and when you press the pedal it moves and pulls the cables or something..
b: Air ingress. If the fuel injection pump sucks in air bubbles, it can cause erratic operation. I don't know whether this applies to the TDI, but other Bosch fuel injectors can "self accelerate" if they are fed too much air. The pipe from the fuel filter to the injection pump is clear plastic. Run the engine and see if there are bubbles of air in the pipe. There should not be, if there are then you have a leak (usually the filter).

------------------
SuperChipped 96 Passat TDI wagon
See my Peugeot / Passat site

Is this a slipping clutch?

When Cruise Control is installed don't forget to take a look at the switches on the gas and brake pedal. Also keep in mind there are two other switched on the gas pedal that gives the ECU the info the gas pedal is pressed and when you press hard (kick-of).

Seat Alhabra MAP sensor

Hi: What causes these errors ?? Map sensor was replaced by line break we could not find ??: Rolleyes:

VCDS -- Windows Based VAG/VAS Emulator
VCDS Version: 12.12.0.0
Data version: 20130910





--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Address 01: Engine Labels: 038-906-019-AJM.lbl
Control Module Part Number: 038 906 019 FC
Component and/or Version: 1,9l R4 EDC G001AG 1455
Software Coding: 00001
Work Shop Code: WSC 02314
Additional Info: VSSZZZ7MZ2V505717 VWZ1Z0A1681199
VCID: 5DB17FFFD7C455F6DF5-4A3A
3 Faults Found:

17678 - PD Unit Injector: Cylinder 4 (N243)
P1270 - 35-10 - Regulation Range Exceeded - Intermittent
17564 - Manifold Pressure Sensor (G71)
P1156 - 35-00 - Open/Short to Ground
17569 - Manifold Temp Sensor (G72)
P1161 - 35-10 - Open or Short to Plus - Intermittent

Rea: Confused: