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1994 W202 - rough engine and loss of power

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by jules_c200, Nov 5, 2012.

  1. jules_c200

    jules_c200 Active Member

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    hi all,

    my (until now) extremely trusty 1994 c200 turned into a growling shuddering monster on the way into work this morning. i was travelling at a smooth 40mph when it suddenly lost power. the car struggles to keep itself going when idling, and is dangerously slow off the mark. it gets up to speed eventually, but it is extremely noisy.

    a search on here points towards a faulty MAF with these symptoms .. but mine is an early model that doesn't have such a thing.

    could someone please point me in the right direction?

    thanks very much, jules.
     
  2. robparker

    robparker Senior Member Authorised Forum Supporter

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    Does it feel like its misfiring, or just a low idle? misfire could be coils (rare on that type as they are under the manifold), ht leads, or worsed case the ignition control module (not uncommon on that engine) No maf as you said.
    Poor idle could be the throttle body, cleaning it may help, but off that its all of a sudden..
     
  3. OP
    jules_c200

    jules_c200 Active Member

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    hi rob, thanks very much for your reply.

    i would say it's misfiring. idling is very rough ... the engine shudders, vibrates and makes noisy metallic tapping noises. it all came on very suddenly, which implies a failure rather than a build up of dirt on something.

    the ignition control module (ecu?) looks pricey. perhaps ht leads and coils would be the place to start?

    cheers. jules.
     
  4. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

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    Pull one plug lead off at a time and isolate the offending cylinder first.
    Obviously not with bear hands and the engine running!!!
     
  5. OP
    jules_c200

    jules_c200 Active Member

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    thanks wg! i'm glad you put the "obviously" bit in ;)

    but here's a daft question - once i've identified the affected cylinder ... what next? presumably that will tell me the specific lead/coil to change?

    cheers, jules.
     
  6. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

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    Exactly
    Although it is very common for the ignition control module to cause a misfire on your vehicle.
     
  7. OP
    jules_c200

    jules_c200 Active Member

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    ok, so i took the cover off the engine, and withdrew the leads from the spark plugs one at a time. here's what i found per cylinder:

    1: same problem
    2: car wouldn't start
    3: car wouldn't start
    4: started with difficulty - then same problem

    can anything useful be read into this?! :(
     
  8. CafeMB

    CafeMB Banned

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    Does the 1994 model have a MAF? If it's a rough idle I'd be looking at plugs, leads, coil packs.

    Get it on Star diagnosis
     
    Last edited: Nov 6, 2012
  9. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

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    If there was no change when you removed number 1 then this will be the cylinder that is losing its spark. You could try swapping the coils over and see if the problem moves to another cylinder although its very likely the ignition modue has failed
     
  10. OP
    jules_c200

    jules_c200 Active Member

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    ok, i'll give that a go ... but i have a nasty feeling that it's the end of the road for the old girl. still, i can't complain ... i got two years out of her for 600quid. thanks very much for your help, all.
     
  11. Some guy on the internet

    Some guy on the internet Senior Member

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    If the PMS unit is dead just buy another & she may last several more years.

    Better the devil you know.............
     
  12. Some guy on the internet

    Some guy on the internet Senior Member

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    If you do buy a replacement PMS unit you must change the coils before installing it or risk blowing the new one.

    What's the number on your PMS unit?
     
  13. OP
    jules_c200

    jules_c200 Active Member

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  14. Some guy on the internet

    Some guy on the internet Senior Member

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  15. WG M-B

    WG M-B Senior Member Authorised Forum Supporter

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    I may have one. I'll have a looky in my cupboards tomorrow
     

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