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Rough Running A170

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Bob India, Nov 14, 2018.

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  1. OP
    Bob India

    Bob India Member

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    Your Mercedes:
    A-Class 2005 A170 PETROL AUTO (W169) Facelift Version
    PROBLEM SORTED.

    Today, I had another go at the car. I swapped ignition leads 1 & 2 with each other. Then waited for the OBDII code to change from P0351 to P0352 indicating that he HT Ignition lead I moved from cylinder 1 to 2, was faulty..

    In reality, I should have done this right at the start, but was bogged down by the two error codes.

    P0068 - Plausibility check of values for components B28(Pressure Sensor) and M16/6(Throttle valve actuator) in idle and under partial load. See above on how this was cleared by cleaing the throttle assembly first.

    P0351 - Ignition spark insufficient at cylinder 1.


    Some Background info.
    This car is very low mileage. Used to belong to my mum who didn't drive it much. It's a 2005 car and in 2008 it had only done about 6,000 miles. Only used now and again. In 2008, my parents went abroad for 4 weeks. The car was left on the drive. One night I noticed a cat waiting by one of tyres. I moved the cat on. My parents returned, started the car and the engine was struggling and running Very Rough and shaking like mad. I managed to drive it to my local garage. They tried a coil from German Swedish French Parts supplier, (GSF), but no joy. Then they tried replacing Ignition leads on cylinders 1 & 2. still no joy. They gave up. So I took the car to Mercedes. They had the car for two days. I thought with their STAR diagnostics they would have the problem sorted in no time. On Day two, I told the Service manager, I wanted a diagnosis and was surprised they could not diagnose the problem in one day and that I wasn't going to pay for hours and hours of investigation !! We agreed a maximum amount. Later on day two in the late afternoon, he said the mechanic had noticed some wire had been cut above one of the ignition coils and that it would need a new wiring loop at considerable cost. I thanked him for his diagnosis and asked him to put the car back together. I picked up the car and took it to my usual garage. I took out the Air filter box and looked under the Air Tubes. I found what looked like chicken wings bones. Clearly, Rats had seen the car was not moving and had made their home under the air tubes, which is a hollow area in the engine. They had then proceeded to chomp through the primary coil supply wires. I bought some wire heat-shrink, trimmed the wires and soldered them. The car was back in operation.

    We have a KFC and other fast food outlets at the top of my road. Dirty disgusting people eat their food as they walk down the road, or sit on garden walls and discard their leftovers in our gardens. I actually had my old Honda Accord in my garden which I was going to sell when I could get round to it. It was left in the garden for 6 months as I had bought another car. When I got round to starting the car, it was dead. RATS had chomped through the big bundle of wires coming from inside the cabin, to the engine. There was no way to fix the car without alot of expense and a new wiring loom. I had to throw that car away.

    In a way I was lucky with the Mercedes. The rats had only chomped about 3 wires close to the ignition coil. Anyway, back to the story. I have read read on some forums, ignition leads should last at least 100,000 miles. This may be true for genuine leads. My mechanic had bought some CHEAP and NASTY leads from German & Swedish Car Parts. These leads were still in the car to this day. Lead on cylinder 1 had failed after just 25,000 miles. I had not realised the original genuine leads had been changed but I had been given the genuine leads and two cheap leads in a bag, which have been sitting in my garage for years. I put the original leads back onto the car and now the car is running sweet..

    On a last note. When anyone comes to these forums looking for help and sharing their experiences, it is important to have a conclusion to their story when and if they resolve their problems. Even if they had to take their car to a garage. Let us know how and what was done to resolve issue. It will help the next person. Also, take a photo of your work progress. It's easy these days with mobile phones and auto uploading to Google photos..

    I hope my experience and pictures helps someone else, and for budding mechanics who want to have a go themselves, you will need an OBD scanner of some sort. I used a ELM327 mini with the Torque Lite App. It won't do full and complex diagnosis like ABS and air bags and custom specific manufacturer features like the LAUNCH system will, but will help with some PowerTrain diagnosis. There are better and more comprehensive OBDII dongles and software, so it all depends on your budget..

    Thank you all for your help and comments..

    Regards

    Bob India.
    (I chose this user name after Ed China from Wheeler dealers.. You can learn alot from watching that program!!)

    ELM327.jpg P0351.png P0352.png HT LEAD.jpg
     
    anyweb, LudwigA200, GLK and 1 other person like this.
  2. mattkh

    mattkh Senior Member

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    Location:
    England
    Your Mercedes:
    W168 1999 1.6
    Thanks.
    I noticed the mayonaise on the throttle butterfly, and guessed the car was used for short journeys.
    Once a month, take the car out on a good thrash to stop that happening.
    Regards
     
  3. OP
    Bob India

    Bob India Member

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    Your Mercedes:
    A-Class 2005 A170 PETROL AUTO (W169) Facelift Version
    Since my girl got her hands on the car, it is clocking up motorway miles and the service light is on !! Guess I know what I'm doing this weekend.. Another oil and filter change !
     
  4. John Laidlaw

    John Laidlaw Senior Member

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    Wirral
    Your Mercedes:
    BMW 530d X Drive Tourer M Sports
    Love the conclusion, thanks for sharing, as you say it’s good to see the end not just the beginning and the journey
     
  5. icky

    icky New Member

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    Location:
    London England
    Your Mercedes:
    Mercedes W169 2007 ML280.
    Bob this video might help.
     
  6. Blobcat

    Blobcat Moderator

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    Your Mercedes:
    R171 SLK280, Land Rover 110 County SW, 997 C2S
    He fixed it in Dec...

    What is the part you're advising to glue? I'm presuming you are the author of the video
     
  7. icky

    icky New Member

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    Your Mercedes:
    Mercedes W169 2007 ML280.
    Hey Bob its the Vacuum Pressure Regulator Valve.
    Cheers
     
  8. spock500

    spock500 Senior Member

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    Your Mercedes:
    300TD, 1998
    Hello folks, similar problem to OP but probably not the same furry issue or least hope not :)

    This is w245 B1700 petrol 2005/6 with no history, basic runaround.

    Cylinder four has a miss determined by pulling HT, removed plug - gap looks huge at 1.1mm although OEM plugs are set to 0,9m which I assume is just under 1mm, not 100% sure as separated by a comma, perhaps denoting something different?

    If someone could confirm correct electrode gap that would be great, ordered a set of Bosch which should be here tomorrow.

    The coil packs which feed 3/4 has two coils, are these independent of each other, i.e could one coil fail (out of the two) leaving the other working fine?

    Complete newbie on this stuff as owned a S124 dinosaur for an age :(

    Thanks for any pointers.
     
  9. ajlsl600

    ajlsl600 Senior Member

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    france
    Your Mercedes:
    clk3202001,sl6002003 with everything regrettably sold ,A class 170cdi auto. NG/TF1800 ML250
    Check out forrera, Mercedes a class specialist.. On Facebook. Based in London. Helpful guy
     
  10. spock500

    spock500 Senior Member

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    Your Mercedes:
    300TD, 1998
    Plugs arrived early, popped those in (real job getting caps off) no change - taped cylinder 4 plug to engine and started, plenty of spark so looks like coil pack okay.

    The catalytic convertor is starting to whiff, possibly due to unburnt fuel making its way back ?
     
  11. LostKiwi

    LostKiwi Senior Member

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    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    If you get a misfire and engine code with Check Engine light then no fuel will be injected into that cylinder to prevent cat damage.
     
  12. spock500

    spock500 Senior Member

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    Your Mercedes:
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    Thanks bud, to cut a long story short it looks like the coils are okay, it does however smell quite strongly of petrol fumes which may suggest over fueling.

    My attention has turned to the variable intake which has a vac operated switch to one side - mine has a split boot but also noting attached, i wondered if some kind member could check there's to see if anything (or it's blocked off) is connected?

    If the intake is closed shut could explain issues as mentioned.

    This video at 4.21 describes the part but cannot hear audio to make out what is is?




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    Courtesy of doit vehicles

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