Hi guys got a problem with my Octavia Diesel Estate 2002 1.9TDI, it runs but lacks power, it is intermitent, power is ok at low revs most of the time, but does not like higher revs, have sprayed the turbo waste gate anyone got any ideas ? cheers

Had it scanned for fault codes?

You say it has a wastegate, so can't be the usual sticky vanes problem

Hi ya, yes had it scanned one fault code I think it was something like P or D 155717965 (bad writing!) something to do with boost pressure, ASV engine so no variable vane turbo. cheers

Thats the same fault code as you'd get if you had a VVT and the sticking vanes.

I guess the wastegated turbos are controlled in the same way as a petrol turbo so I'd start checking the N75 valve and all the associated pipes, wastegate as well although it sounds like you've had a look at that already.

Hi thanks for that, the vacuum pipe connected to the wastegate diaphram has suction. I fitted a length of hose with a syringe and tried creating a vacuum to see if the linkage actually moved but could not see any movement. I don't know if this is normal. Can you confirm what the N75 is cheers for your help.

On the 1.8t the N75 is a little valve coming off the inlet pipework, it has connections to the inlet pipework upstream and downstream of the turbo and a third connection which is a vac pipe to the wastegate actuator. Its connected to the ECU with a multiplug too. I'm not sure if the 1.9TDI has an N75 but if it does and this has failed then the wastegate will be stuck in an "open" position to prevent the turbo overspeeding

I thought only the early 90TDIs had wastegate based turbos and then everything was VVT based. 2002 isn't classed as early in my book as that is post facelift.

However, on my 2001 110TDI if I suck on the pipe from the n75 to the turbo I can make the actuator on the turbo work. I assume (but have no evidence of this) that the level of vacuum will be approximately the same, regardless of turbo type. It maybe that your syringe simply wasn't removing enough air.

I would check and potentially replace all the smaller fabric covered vacuum pipes I did this on mine as some were looking quite unhappy, especially the one from the vacuum ball. They have 2 different sized (internal diameter), your local dealer should be able to flog you a few meters of the stuff. I found it very difficult to source a few short lengths from anywhere else - I even tried marine places (I live on the coast).

n75 location (pre-my pipe tidy up):

Hi thanks for your responses the problem seems to be intermittent, sometimes it seems to pull ok, other times it seems to have no oomph! on accelerating hard today the turbo started to whistle then went silent as if the boost disappeared then the power was lacking.

I will try sucking on the pipe to create a vacuum rather than the syringe, I will check the pipework and thanks for showing the location of N75.

If your engine is an ASV then you do have a VNT turbo - same engine as my car and I know I have an VNT turbo!

Right then:

- sticky vanes

- CTS

- MAF

- n75

- vacuum leak

are my guesses (in no particular order)