Hi all

Was out in the car this afternoon when heard a pop when accelerating away in third. Had the usual loss of power and a bit of black smoke out the back, then just complete lack of boost and so pretty slow performance.

Had the timing belt done a few weeks ago so assumed it was a loose boost pipe, have now checked all hoses from turbo to intercooler to intake and all look fine.

Have had no warning signs, no strange turbo noises and no sound of any boost leaks.

Seems almost as if the wastegate suddenly opened and stayed open, but guess that this could be because something else has failed like boost sensor or the vacuum control unit???

Car is 05 on 73k, has no mil, no history of any turbo or boost pipe problems, is very well maintained by me and is always driven with full respect for the engine mechanicals.

Any advice or suggestions would be gratefully received, really hoping that not turbo failure (as no warning signs before and no evidence during or after that turbo has gone).

Thanks

Andy.

Have you actually checked the connections to intercooler? Pops happen under pressure, black smoke indicates it too. I recone a close r look. As when the cam belt is done the boost pipes need moved anyway. Pull around at each joint, underneath too, may need to remove some plastics and grill pieces to check properly. Or evven intercooler failure itself

Edited 19 August, 201213 yr by Lofty79

Have been all over and under the car this afternoon checking everything.

All the hoses got a good wiggle and all clips and joints seemed fine. Dismantled the top ones that would have been removed when timing belt was done and reassembled, no probs there either.

Really got me stumped, seems no other evidence of turbo failure, so really hoping it`s not that, but was hoping to find something obvious!

No boost at all now and no noises that would suggest a slight leak somewhere, just seems unable to create any boost at all.

Am assuming that mil would be on if boost sensor failed or the vacuum control unit was not actuating the turbo properly. Did check that the vane actuator arm on the turbo was moving ok, but did this by hand rather than vacuum pressure.

Cheers for thoughts, keep em coming...........!

Andy

Suppose i could always swap vacuum controller with another local vrs to see if that is at fault (n75).

Worth a try

Just need to hope that a friendly local member reads this then................ ;-)

Does boost come back when you restart the engine?

Nope, have test driven about three times now to see if any of my checking, or sheer luck, had fixed the problem.

Andy

Anymore black smoke? Could also be maf sensor. If you go to 3500 revs do you get a bit of boost? This happened to mine no management light, but powerless, got boost occasionally at very high revs, was maf

Just been out to try what you suggested, some black smoke when foot down but ok when cruising. A little blip of something at high rpm but no proper boost.

However now has developed a high pitch mechanical squeal which happens every now and then and seems linked to engine speed. Guessing that this is turbo shaft or vanes making the noise so not a great sign!

Seems to squeal a bit at lift off then continues when foot back on it.

Great!!!

I had the same thing happen a day after a cambelt change. Pop with a slight air woosh sound, then almost zero power and loads of soot. Was a pipe but not sure which one. Garage says it's very common and replaced the pipe o ring as well fitting self tapper to make sure it doesn't come off again

Mine was also making a mechanical grinding noise, sounded like the engine management was desperately trying to 'fix' the conditions, dumping alot of fuel into the engine for one

here we have a poss solution, there is an o ring in one of the joints that could be replaced, even if joint seems ok. Squeeling isnt great though, unless its boost air forcing its way past a small gap, maybe needs a really close inspection of all joints.

I actually still maintain a boost leak mate, i know you have been thorough, but small amount of black smoke, SOME boost at high revs etc etc.

Just to illiminate it, unplug the MAF and see if it improves any low end driving.

Not sure which oring you mean??

Just been out again, noise is defo not air, is a mechanical squeal. Was there at start up but after a minute of idling it stopped and didn't come back. Drove off steadily increasing revs and then mil came on at approx 3000rpm. Don't have vagcom, just obd, so cant check code.

Tried maf but no change.

Will have to get code read tomorrow, see what that shows, strange how mechanical squeal came and went and is now replaced by mil?!?!

Edited 19 August, 201213 yr by A Woodster

Once the pipe had popped off I couldn't hear any air

Am very confident that this is not a popped off pipe or a boost leak.

Aye I'm with you now. Could be seized turbo, which you dont really want. Let us know what the codes say pal

I agree that i don't really want that!!! ;-)

Strange for it seize at full boost with pop sound and no build up of noise though.

Edited 19 August, 201213 yr by A Woodster

codes it will have to be.

although the symptoms don't fit i keep coming back to the sticky vane issue.....

I will check again in the morning, but how much actuator movement should there be??

When i checked today there did seem to be about 5mm or so of free movement, but i wasn't putting too much force on it.

Is it ok to free by repeated movement, if it feels like it should be moving further, or is it best tackled by mr muscle treatment?

Cheers

Andy

mr muscle wont hurt it. you know i am the biggest mr muscle advocater there is. your symptoms dont fit but you never know

http://www.briskoda.net/forums/topic/243533-the-mr-muscle-vnt-turbo-treatment-thought-we-needed-a-guide-of-sorts/page__hl__+vnt#entry2902732

roughly how much actuator arm movement should I be aiming to achieve - am going to check this again in the morning before i invest a load of time in the mr muscle treatment.

If i have free movement then seems no point in doing mr muscle, if movement is restricted then may give it a go.

maybe 10mm? and it should be smooth not gritty.

only takes half hour, plus the 2 hours soak of course

cheers, will check tomorrow.

Have you seen MILs before when the cause of the running problem is sticky vanes or is it only ever limp-home (activated on each run when overboost occurs, rather than a permanent state that it seems to be on mine)?