Mk2 1.9Tdi Turbo On/off

[Yozza]

The battle bus has recently developed an annoying problem.  The turbo will switch off (i.e. no power and won't rev), however, if I switch the engine off and restart it's back to normal and pulls away.

 

In the summer I had to sort the head gasket, so while the head was off I stripped the turbo and gave it a good de-coking (freed up those vanes and ring) so I don't think it could be that.

 

Any ideas? 

 

Cheerz

[seatkid]

If its a mk2, when you get a turbo related fault (usually under or over boost), the ecu will trip into limp mode and stay in limp mode until the ignition is turned off and back on.

 

So its probably still sticky vanes, I'm afraid.

[f0ster]

I have also seen it caused by the pipes taking the boost pressure to the ecu, they get oil in them and then the pressure has difficulty getting to its destination, when it does overcome the blockage it overshoots causing it to go in to limp home,

[Yozza]

Thanks fellas.

 

Those vanes were as free as can be by the time I'd finished with them, unless the cold weather is having an affect? 

 

When I took the head off (engine still in car) I remember thinking the turbo would be a pig to remove while the head is still on the engine.  Although surely to service a turbo, you can't be expected to remove the head?

 

Cheerz

[xavier]

removing the driveshafts will give you clearance from below. I'd suggest removing the undertray and checking the action of the vanes using your finger or a spanner (can't recall the exact size, sorry!). That'll confirm if the vanes are coked. I'd be inclined to agree that if you decoked it fully it shouldn't be a problem now, so vaccum lines would be my next call.

[Yozza]

Thanks for the reply, I'll do some investigating.

 

Although the misses says that the bus goes into limp mode if she is travelling up hill, does this shed any more light on the possible root cause?

 

Cheers,

Yozza

[seatkid]

Thats because going uphill demands more power/torque, i.e. more turbo boost. - we're back to the the sticky vanes or leaky vacuum pipes again.

 

She might be able to fare better by changing down a gear when going uphill - that will demand less boost.

[Joey P]

Any of you tried a chemical approach to cleaning the turbo.

 

If so, did it work? or can these sort of things work?

 

http://www.ebay.co.uk/itm/Innotec-Diesel-Turbo-Cleaner-Kit-Solves-Your-LIMP-MODE-on-all-VNT-Turbochargers-/220934225460?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3370b4be34

Edited December 3, 2013 by Joey P

[cyborg]

A Faulty mass air sensor can also replecate the fault. Try disconnecting,the car will run in default mode until you replace.

[xavier]

I tried the chemical clean, worked for me and freed up VNT mech, but had a limp mode last week so need to have another check of the VNT mechanism.