My 112000 mile A4 (1Z engine) has developed an intermittently running turbo. It sounds normal when it runs, it nearly always works at first but at some point it packs up and doesn't start again during that journey. It may have gone 2 miles or 100 before it stops giving boost.
Wow is it slow without the turbo.
Any ideas anybody, I am wondering about sensors.
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Could be coked-up bearings, by which I mean bearings so smothered in solidified oil the turbo is no longer turned by exhaust gases.
HJ
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"works at first" may be a clue, perhaps the wastegate is sticking open.
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Just my thoughts too Darcy, spot on. Usually vacuum operated, so a quick check of the pipes might reveal the cause.
Mike
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Most systems these days involve having a closed crankcase ventillation system, that is to say that the crankcase blow by is piped directly back into the air intake just before the Turbo. The problem with this is that the blow by is full of dirty engine oil and particullate. Some producers put a simple baful in the way and maybe a simple pressure /vacuum regulator, but essentially this is not enough to protect the turbo or other parts of the injection system.
On larger generator sets which run continually eg Catapiller engines the turbo is protected by a high purity filter/regulator. Some vehical companies are toying with the idea but are put off by the addition of £15 - 20 or so to their base costs.
Have a look to see if there is a pipe going from the top of the crank case to just before the turbo, if you pull it off and have a look inside the pipe, I bet its full of dirty oil.
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Thanks everyone for your comments.
Over the weekend it wouldn't even go properly from startup. I took it to my local VAG independent (it's the first time since I bought it in May). He thought it might be a solenoid but it turned out to be a disintegrating cat blocking the airflow, he's fixed it. He seems to know what he's talking about so I'll be going back there.
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