please help lpss of power

[Andrew Reid]

i have a seat alhambra 2002 1.9tdi and the turbo only work at certain times mainly not working especially up hill .
i have replaced the maf the n75 valve the fuel filter the air filter and it has been checked for air leak.
and today i have changed the turbo still no joy so at my wits end and the garage are scratching the head i took it to another garage for second opinion and they the ones said turbo.

so anyone got any ideas or had the same problem??

[micheal balbrig]

Did the second opinion come as a result of a diagnostic scan.
No point in being at wits end, whatever the problem is, it can be sorted in time.

[Andrew Reid]

yes it was and they just could not get the turbo to work even after by passing the n75 valve

[micheal balbrig]

Probably best to try posting scan results here and wait for reply from the helpful expert members,of which there are many.

[Andrew Reid]

i have no scan results i am going back to garage what said it was the turbo that needs changing and see what excuse they got now

[glowplug]

Ideally you want to get a VAGcom scanner off ebay, they are cheap and will provide you amazing visibility into what the car is struggling with. Have you checked the wastegate/dump valve. If this is stuck open you will get no boost whatsoever as all the exhaust gasses that spin the turbo vanes simply bypass the turbo. The N75 valve simply controls when the wastegate opens but ultimately the wastegate controls the boost. Failing that check you don't have a collapsed catalytic converter matrix that could be causing too much back pressure and failing all of that you may want to check individual cylinder compressions. Another is the EGR (Exhaust Gas Recirculation) valve. Again if this is stuck open you will get lots of black smoke but no power.

Other suspects are the crankshaft position sensor, (if it has one) camshaft position sensor or the Throttle Position Sensor (generally attached to the gas pedal on a diesel as they are drive by wire). The ECU needs input from these to deliver the correct amount of fuel to the engine. Sometimes a fault may appear to be turbo but are actually because the car has gone into limp home mode and is under fuelling.