Odd loss of power Mk3 Tdi

[sparkie]

Just wondering where to start looking, I have a Mk3 Tdi, and recently it has been misbehaving, acceleration is a little slower than before, and, whilst I can hear the turbo whine as it get going at about 2100 rpm the car suddenly loses power, especially when it is hot going up a hill, and I feel like I am in 'limp-home' mode.

My suspicion is the intercooler leaking somewhere and dumping the pressure, but where should I start looking, the intercooler is buried behind a load of plastic, are there more likely places to look?

[Ryeman]

By odd, I assume you don't mean occasional.

[sparkie]

Odd as in unpredictable, some days it is really pronounced and can barely get up steep hills, others it races up them, no sense to it' except, I think, it does it more when then engine is hot

[Ryeman]

Sounds like something sticking .....could it be a dirty egr valve.
start with the easy to get at things IMOIMO

[sparkie]

Blanked out the vacuum hose to the EGR, and it's still happening! Is there something else I am missing?

[sparkie]

This is really frustrating, just had a service, nothing found by the mechanic, no hisses from the hoses, with the vacuum hos blanked off, I assume the EGR valve is not opening, but the problem persists unpredictably...

[Ryeman]

This is really frustrating, just had a service, nothing found by the mechanic, no hisses from the hoses, with the vacuum hos blanked off, I assume the EGR valve is not opening, but the problem persists unpredictably...

Sounds like the service div didn't try all that hard.

[Gigitt]

I know it's a Couple of months old..

Sounds like a boost hose leak to the N75 valve, or faulty/sticking N75.
Have you scanned it for error codes?

[lynnos]

Hello sparkie, can you come back and tell us how your problem ended up if it has.

[sparkie]

Sure thing, lynnos. So far I have had the diagnostics checked, and no code is being thrown by the management system, I have totally removed the hoses and intercooler from the turbo cleaned and inspected the pipes and hoses, and can see no cracks, tears, etc. The intercooler was a a little clogged up with crap so that's all clean now. It is still an intermittent fault, it seemed to be OK for a few weeks, lots of boost going up the Hinterland hills, but then suddenly I'm in the crawler lane barely getting up hills it sailed up in 4th 2 days before. I can hear the turbo spool up, feel the boost (though it's perhaps not as strong as before) and then suddenly the torque drops and I am scratching round for gears on a hill.

I'm only a basic mechanic, the turbo scares the **** out of me, so I'll spend Sunday looking around at where the N75 valve and hoses are and what condition they are in

[G60ING]

Odd loss of power Mk3 Tdi

I would replace the N75 if it hasn't been replaced ever. Also I would try to use a pump (tire pump, air compressor or vacuum hand pump) and try to get the waste gate to move on the turbo. I've seen these seize up before.

I had a similar problem with my AHU after swapping into my corrado and doing a bunch of upgrades. With a boost gauge installed I would be WOT ~14 and then it would drop to 7psi. After doing all of the usual maintenance items & checks I still had the problem. I finally just upgraded the turbo and chipped it.

[gldgti]

easy for me to say ofcourse, but dont be scared of the turbo, its a VERY simple machine itself.

Do you actually have a boost gauge? If you can plumb one in (even temporarily, like a couple of m of vacuum hose into the cabin through the drivers window) it might help diagnose the actual problem.

For instance, when you lose power, and you also are trying to get up the hill, does the car blow smoke?

[h100vw]

For instance, when you lose power, and you also are trying to get up the hill, does the car blow smoke?

This would be the biggest clue to a boost leak. Fuel injected for perceived airflow that isn't making it into the engine. So running way rich.

Wastegate could be getting intermittently jammed too. If there's no smoke.

I like the boost gauge idea to see what it is making.

Turbo's have pretty much one moving part in the middle, nothing to be scared of.

Gavin

[Ryeman]

Blue smoke oil black smoke diesel?

[sparkie]

I can't seem a to find an N75 anywhere for a mk3, is the mk4 valve suitable?