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Lack of turbo after I go through water

Bleednight Jul 25, 2017

  1. Bleednight

    Bleednight Registered User

    Hi, I have an Audi A4, B6 from 2001 1.9 TDI 130 bhp, the motor code is AWX ( will confirm when I get home )
    So I have a small oil leak ( will go to a service on thursday) and when I go over small puddles if I get some water splashed under the car the turbo won't enter anymore for like 1h ( I think until it or something else dries up). I went on a small trip and went through a lot of water there but the turbo made an heroic stand and stopped after 30 min ( enough to get out of a big storm with water over 1 inch in road ). I arrived at home and after 6h want to go to work but when I put in 2nd gear I can't rev the engine. It won't go over 1700 rpm and died if I didn't hold the clutch.

    I put the car in neutral and rev it a little, something like a white-grey smoke was coming out of the exhaust. And I tried to have a constant 2300 rpm but the engine went to 2100 on his own, and I think I heard something at the engine. If I hold it under 1700 rpm the engine behaves like normal, but the turbo wont come in and it gets hard to rev up while driving.

    The oil level is right and it has the classic black color.
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  3. Spatula

    Spatula A4 B6

    As long as it's the classic black. :redface:

    White/grey smoke is oil being burned around your turbo. If your turbo has got up to temperature (extremely hot) and then been doused in cold water, the sudden temperature change can cause fatigue in the turbo housing. If this happens enough, cracks can appear. The turbos are being cooled to a maintainable temperature by a constant oil feed which keeps the turbo cool enough so that the internals don't weld themselves together. There are a few possibilities of what has happened:

    A) There is a crack and you're losing oil into the turbo casing/FMIC which is in turn being burnt on the hot side, causing white/grey smoke, and your turbo is in limp mode because of mixture

    B) Your turbo has seized due to oil leak, so you are burning excess oil on hot side

    C) Your turbo has blown due to temperature fatigue/oil loss and you've got oil running into the charged air feed

    If you are saying that the car is running to 2100 on it's own, this could possibly be what is known as 'run away' (early warning signs there of), which is when oil is being forced into the combustion process by it's own accord, and is causing the car to over fuel itself. If you encounter a runaway while driving, the car will start accelerate uncontrollably which may cause you to crash, depending on your driving skill and the ability to keep your calm or not. A stationary runaway will basically destroy the engine if not stopped in time. Depending on conditions, the engine might even rip itself open, spraying shreds and pieces all around the place.. Please take a minute to familiarize yourself with what engine run away is, and how to deal with engine run away. This can save both your engine and your life should you ever experience it.

    Wiki link ---
    Stopping runaway --- https://www.carthrottle.com/post/w8ookb3/

    My advise would be first check for oil leaks /oil buildup at the FMIC connections. Easiest way to do this is to create an oil drain plug by drilling a 3mm hole in the pipe directly after FMIC, and seeing how much oil flows out. Plug the hole back up with an M3 screw.

    Best case scenario, turbo in limp mode
    Worst case scenario, blown turbo and debris (oil and impeller fins) dispersed around your engine internals.
  4. Bleednight

    Bleednight Registered User

    Thank you for this very good answer , the car was not reving on his own, I was reving it, sry if I wasn't clear enough. I will go at a mecanic in 2 days, I am curios if it will be warm weather and it will go back to normal, someone told me to get the right pole off and at the electrovalve to clean the sieve, and maybe that should fix it. I think it's an electrical problem because of it only apearing when it's water entering somewhere. Will kep you updated.

    Just to know it's posible to get the water from somewhere? Because when I got home at night there was no visible smoke and the car was still going good except for the power loss which was bigger this morning.
    Last edited: Jul 25, 2017
  5. Spatula

    Spatula A4 B6

    I would say get it on vagcom and read the fault codes that are being thrown up. It could be N75 however that wouldn't explain the smoke. If the N75 was at fault it would not actuate the turbo and you would just have limp mode. The reason for power when it happened and then not in the morning is that during the 5/6 hours of not being used, the turbo has cooled down and the casing has essentially shrunk, which would make cracks etc. more susceptible to do their thing.

    It's hard to diagnose from behind a keyboard but the mechanic should check all possibilities. As I said, vagcom should point you in a better direction.

    Hopefully it's a bad boost sensor or N75.
  6. DieselJake

    DieselJake Well-Known Member VCDS Map User

    Yeah I'd say get rid of or clean the EGR first as mine had similar symptoms before, that or maybe the plug under the battery needs removing as the rain is flooding the CCU.

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