- Smoky 1.6SR when at 90º - Failed MOT Emissions
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    1. 04-21-2019 05:39 AM #1
      Hello everyone,
      I'm almost without any hair left in my head due to lots of scratching...

      I (well, my girlfriend) have a Golf MKIV 1.6SR, that is extremely smoky and with loss of power when hot, 90ºc.
      Recently it failed Emissions Tests on MOT.

      The smoke is something gray... light gray.. It doesn't smell like burning oil, and coolant level don't change.
      The smell remembers me like light up some matches.. Its not that traditional smell when an engine is running rich... but it really seems that at that Temp (90º) it starts to run super rich, leading to the miserable fail on the emissions tests.
      Last year it passed because they made the test with the car around 70ºC...

      I've tried to connect VAGCOM and read a few things... As car is old, there's no such thing as Readiness, and that stuff (measuring blocks 30, 32, 33... and 70's if I'm not mistaken)
      All I can get is some lambda voltages, that vary between 0.1 and 0.9, as excepted I think, until car gets hot.
      Once coolant temp reaches around 90ºC, the lambda voltage stuck / freezes at 0.9V, and the smoke starts.

      I have no idea if the car smokes because lambda freeze as 0.9V, or if it freezes because the car started to smoke.
      Everything else in the car is pretty acceptable, so we would like to sort this out..

      Vag.Com Engine Errors:

      Friday, 19 April 2019, 21:22:38.
      VCDS-Lite Version: Release 1.2
      Control Module Part Number: 06A 906 019 
        Component and/or Version: 1.6l R4/2V SIMOS HS2387
                 Software Coding: 04000
                  Work Shop Code: WSC 01317
                            VCID: E0B3A383735B
      1 Fault Found:
      00515 -  Camshaft Position (Hall) Sensor (G40)
              27-10 -  Implausible Signal - Intermittent

      I've found this exact same problem, or at least symptoms in some websites / foruns, but the whole thing (thread) dies without an answer..
      Any help is very welcome.
      Thanks in Advance,

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    3. 04-22-2019 06:09 AM #2
      I bet on lambda, it should fluctuate voltage...cold engine runs without lambda because it is not heated

    4. 04-22-2019 10:43 AM #3
      Or maybe the Lambda system is working fine and it's telling you that the engine is running really rich.

      Try unplugging the O2 sensor and see what happens. Typically when an O2 sensor fails, it will be shorted [0V] when this occurs, the engine computer will add more fuel. It will add so much extra fuel it can stall and at a minimum, blow a lot of black smoke.

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    6. 04-23-2019 11:31 AM #4
      Quote Originally Posted by Butcher View Post
      Or maybe the Lambda system is working fine and it's telling you that the engine is running really rich.
      That's my problem.. if that's the case, what can be telling the system to add fuel once engine is hot? (closed cycle?)
      If there's anything I can read with vagcom to help understanding the problem, just tell me.

      I'll try disconnecting the O2 sensor.
      It's the first one, before the CAT, right?

      Thank you.
      Last edited by ahlidap; 04-23-2019 at 11:33 AM.

    7. 04-24-2019 10:17 AM #5
      I certainly would check the coolant temp sensor. Power supplies and grounds are important too. I'm not certain if you could look at actual values while it is running. Something may look odd and point you in the right direction.

    8. 05-02-2019 11:48 PM #6
      your cat is melting down from it being too rich and too old

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