2.5TDI - Loss of power

[JLLL]

Hi all,

My '96 2.5TDi is suffering loss of power. I took it to a diesel specialist and they said:
1. No faults read
2. Found air mass and boost pressure low
3. Supply pressure to wastegate on turbo, which should lower boost, but on road test it increased.
4. Suspect turbo fault.

I'm not convinced on their findings. I guess when they pressurised the wastegate that they tee'd off from (or bypassed?)the N75, but I'm not sure.

What I really dont get is how can boost pressure increase when pressurising the wastegate? As far as I know, pressure to the wastegate actuator can only open it and dump the boost?????

I very recently found that the EGR valve vacuum hose had a ball bearing shoved in it, which I removed, and then serviced the EGR valve which was stuck shut. It now moves freely but the diaphram could be shot inside.

Unfortunately this car is mainly town driven, not motorway cruised. After a good long run performance normally improves for a week or so.

So what can it be?

A charge problem?
Turbo is knackered (I hope not)
Wastegate is sticking open (possible I suppose)
N75 ( resistance is 21 ohms, which is in spec)
Leaking hoses (cant find any)
Catalytic converter (doubt it)
MAF (apparantly it works)
inlet manifold coking (stuck my finger in there, not that bad)

Or a fuel problem, causing the ECU to limit boost (is this possible) ?
Lift pump
Injector wear

Or, to some extent all of the above? (it quite an old car now I suppose).

Any ideas or explanations very greatly aprecicated.

[buster]

A bit of a long shot but may be worth testing.

I had a 1.9TDi with a power loss and it turned out that the MAF was giving incorrect figures. Not because it was damaged or worn out but because the electrical feed to it was intermittent.

There was a blade fuse in the feed to it (In a box with the ECU in the plenum chamber) and this had a loose blade causing loss of power to the MAF. This caused all sorts of problems with the engine including a total turbo pressure loss. I am not sure how it did this but changing the fuse cured it.

I measured to 0-60 at 58 seconds.

Might be worth checking incoming voltages to sensors.

[pgarner]

was the 58 second 0-60 before or after the fix ? im hoping before

[buster]

was the 58 second 0-60 before or after the fix ? im hoping before

I was trying to convince the garge where I had bought it two days beforehand that there was something wrong with it so I tried this - yes before they fixed it.

After, it was around 12 seconds.