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W124 Running and fueling issues.

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Karl W, Nov 17, 2012.

  1. Karl W

    Karl W Active Member

    Messages:
    42
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    Joined:
    Jul 4, 2010
    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    Hi,

    I've been struggling with what I think is a mixture issue on me 1995 e200. The car starts fine, and initially runs ok as the car warms up it will start to pop and cough until is stalls.

    If I spray some fuel straight into the air intake the car then will run OK again for a while before dyeing again, spray some more fuel again into the air intake and it runs fine again. I managed to get hold of a fuel pressure testing guage and the pressure is fine at the pumps and at the rail.

    I'm thinking now that there could be a problem with the throttle housing, what things can I do to check the throttle housing. I can't find any air leaks and all the hoses look OK.

    I've checked the engine temp sensors and they all check out, the error codes I have relate to lean mixture. The Lambda sensor is OK, fuel pressure is constant at the rail. I'm at a loss on what else to check, and find out why I get lean mixture.

    As anyone else had a similar problem, or had problems with the throttle housing?
     
  2. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

    Messages:
    3,105
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    6
    Joined:
    Dec 5, 2010
    Location:
    North west london
    Your Mercedes:
    C63 Wagon in black
    The wiring degrades both on the main engine harness, and the throttle actuator looms also give trouble. Can a specialist near you not check the car on star???
     
  3. OP
    Karl W

    Karl W Active Member

    Messages:
    42
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    0
    Joined:
    Jul 4, 2010
    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    My local garage havn't got the star system, but they can clear and read the codes from the ECU.

    It might be worth me asking the garage to check the trottle acutuator looms, just for my own knowledge where about the the loom for the the trrottle acuator start and finish ?

    I took the car over the my local garage when I couldn't find the issue, I trained in machanical engineering so I only take a car to the garage when I can't fix it. I hate to think it but the old Merc may get taken to the breakers.
     
  4. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

    Messages:
    3,105
    Likes Received:
    6
    Joined:
    Dec 5, 2010
    Location:
    North west london
    Your Mercedes:
    C63 Wagon in black
    The loom is part of the actuator. It's plugs to the main harness under the inlet manifold. The wiring loom to the air mass sensor/ air mass sensor itself is also a possibility. It's best to check it on star. It really shouldn't need the breakers!
     
  5. OP
    Karl W

    Karl W Active Member

    Messages:
    42
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    0
    Joined:
    Jul 4, 2010
    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    I hope it doesn't get to the breakers, I'm not sure what diagnostic system they have at the garage but they can read what all the sensors are doing and can read current codes, and stored codes.

    All the coils have been replaced, the PMS control unit to has been replace too. I can assume the other ECU unit that lives at the back of the battery should be ok otherwise it just wouldn't work.

    I'll ask them to to check out that section of the loom, they also found a slight break in the wire that plugs into the the air flow sensor. I'm thinking it may be worth replacing the sensor again and just repair that bit of wiring. I think it just got caught whilst checking things and being pulled appart and rebuilt over the last few weeks.
     
  6. drivemycar816

    drivemycar816 Active Member

    Messages:
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    Joined:
    Nov 17, 2012
    Location:
    UK
    Your Mercedes:
    2004 E320
    I agree. Bring your car to the nearest specialist especially if the breakers might be affected. Good luck mate.
     
  7. OP
    Karl W

    Karl W Active Member

    Messages:
    42
    Likes Received:
    0
    Joined:
    Jul 4, 2010
    Location:
    Wakefield
    Your Mercedes:
    Merc (W124) Estate , Mk2 Golf GTI (Under Rebuild)
    At the moment it woukd have to get there on the back of a tow truck.
     
  8. DIYMAN

    DIYMAN Senior Member

    Messages:
    416
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    Joined:
    Dec 16, 2007
    Location:
    Nr. Harrogate
    Your Mercedes:
    E270cdi/53 plate/2.7l 5cyl.
    On my 230E W124 I found a split in the rubber moulding under the throttle housing, it is very difficult to detect but maybe seen with a small mirror if you can press on it and watch in the mirror at the same time. I managed to do a repair using gun Silicone after removing it. Hope this helps.
     
  9. kth286

    kth286 Senior Member

    Messages:
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    Joined:
    Nov 4, 2002
    Your Mercedes:
    E320 Coupe 95
    that model uses a MAP sensor as opposed to a MAF does it not.

    the clue must be that it operates on the fixed map until it gets warm, and then switches to live MAP sensor inputs.

    So I am guessing the MAP sensor needs a good look at/swap for a known good one.

    Have you checked the continuity of the wires and (leakage to earth) from the MAP sensor back to ECU also.
     

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