W203 C180 K - High Emissions - MOT Fail

Discussion in 'Engine' started by KettavaN, Mar 14, 2019.

  1. KettavaN

    KettavaN New Member

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    May 20, 2010
    Hello all, newbie to the forum and in need of dire help

    I'm in need of some guidance here. I have a W203 2004 C180 Kompressor which was sitting idle in my garage for nearly 6 months (didn't need the car). Last week, I took the car to a garage to get the MOT and full service done again.

    MOT Fail - As expected the car had a long list of faults and I agreed with the garage to get it all done. I had the check engine light on when driving to the garage.

    One of the faults was the blowing exhaust, this was thought to be the cause of high emissions at the first MOT attempt. They had it repaired and to their surprise and mine emissions were still high. They advised that there might be some oil in the exhaust and emissions are caused by the oil burning out. They asked me to take the car away for the weekend and keep the engine running/drive it in low gears which I did for 3 days. The check engine light came up again while the engine was running and it was P0171 - System too lean (Bank 1). I cleared the error but came up again when the engine was left running for a while - this doesn't occur when I drive the car.

    I informed the garage guys about the error code and they agreed to look into it. They had the car for 5 more days and came back to me saying they have done everything they can and the emissions are still high. From their checks MAS, CAT, Lambda sensor all are okay.

    I wonder if this is caused because I've been driving around with a blown exhaust and the ECU has learned/adapted to it. Is there a way to reset the ECU completely (including Fuel trim / LTFT)

    Any help on this topic would be highly appreciated, I am just running out of time, patience and money. I already spent £900+ on this car. I just don't know what to do now.

    VIN: WDC2030462R164854

    Emission readings; First
    Engine speed: 2314rpm
    CO: 3.90%
    HC: 227ppm
    Lambda: 0.89

    Emission readings; Latest
    Engine speed: 2356rpm
    CO: 3.93%
    HC: 278ppm
    Lambda: 0.88
     
  2. alecmascot

    alecmascot Hardcore MB Enthusiast

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  3. markjay

    markjay MB Club Veteran

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    W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk
    KettavaN likes this.
  4. OP
    OP
    KettavaN

    KettavaN New Member

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    I did see this thread before but quite didn't understand this. I'll add this to my notes to mention when I go to an MB specialist tomorrow. Any other suggestions? I read in another thread that if you disconnect the battery for more than 30 mins the ECU will fully reset; I am doing it anyway to try my luck. :(
     
  5. OP
    OP
    KettavaN

    KettavaN New Member

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  6. markjay

    markjay MB Club Veteran

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    W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk
    Come to think of it, the M271 engine has several typical issues:

    - Timing gear failure: if the engine timing is off, it could possibly affect emissions, but I would also expect unusual engine noise. Very expensive fix (~£1.5k).

    - Split vacuum hose under the air filter housing: this can cause lean mixture, but then I would also expect rough idle. A replacement hose is inexpensive, but there's a considerable amount of labour required to get to it.

    - Blocked engine breather: this could bring up the EML but I am not sure if it would affect emissions. Cheap and easy fix though.

    Good luck.
     
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  7. OP
    OP
    KettavaN

    KettavaN New Member

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    As of now, I've tried cleaning MAF, Lambda sensor and got the garage to check if the Cat was ok as well. I think they are as lost as me.:(
     
  8. OP
    OP
    KettavaN

    KettavaN New Member

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    Thanks a lot for your help
     
  9. design guru

    design guru Hardcore MB Enthusiast

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    I had this on my 2001 S320cdi which would let out a cloud of black smoke when I kick down, a small amount of smoke is expected but anything that could impair the visibility of the driver behind would be dangerous and be a fail. Before I got away with just running some REDEX to clear the system pre MOT so when they checked it it was acceptable levels but now I found out under the new rules they rev the car to motorway revs for a few minutes and then kick down to simulate an overtake and see what is thrown out. Mine failed miserably until I used a can of Normfest DC980 Diesel Intake Cleaner, I am in no way plugging the product and saying its guaranteed to work but it sorted my car no problem. Even the MOT guy asked me how I managed to sort the problem, I also changed the fuel and air filter for extra measures, but It might just be a simple case of using premium fuel and this will also help. I used the entire can spraying through the air intake when the car was heated up after a run and then let the car sit for a few hours, when I took it for a run the amount of smoke was terrible, but it cleared my system well enough to pass it. Mine has 230K and I have been advised the manifold is blocked. All I know is now I kick down and it leaves no smoke unlike before I would avoid kicking down when ever possible. I got it from ECP.
     
  10. amazighman

    amazighman Hardcore MB Enthusiast

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    Lean fault are caused by vaccum leaks....
    First have the intake smoke tested , they put a machine which pumps loads of white smoke into the intake and if smoke escapes anywhere then thats your leak. Cost be 25 quid
    Could also be a dead or dying o2 sensor.
     
  11. Bellow

    Bellow Hardcore MB Enthusiast

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    Lambda < 1.0 indicates rich mixture.
     

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