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  1. #1
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    1972 Merc 280SE 3.5 V8 running probs

    This V8 engine type was also fitted into later 350's .
    The problem I've got with it is rough running that started suddenly a couple of months ago . If you slowly depress the throttle it will accelerate smoothly to full revs but if you floor the throttle quickly it thumps and bangs and decelerates to idle speed ( but doesn't cut out ).
    I've checked the timing , replaced the points and condenser , and checked the fuel flow to the fuel rail - it's getting loads .
    I've also cleaned the 4 breaker points ( that sit under the base plate in the distributor ) that control the electronic fuel injection - 1 set of points runs 2 cylinders each . They were slightly oiled up but it hasn't cleared the acceleration problem .
    Has anyone got any ideas please because I'm all out !

  2. #2
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    Oh man no idea on this. I'd honestly say best to take it to a mechanic who specializes in older German cars.

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    Isn't the 280SE supposed to be a 6-cylinder?

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Isn't the 280SE supposed to be a 6-cylinder?
    The regular 280SE IIRC was a inline 6 but the 3.5 was the V8 - highly collectable and sought after - especially the convertibles. Gorgeous cars.

    OP - Where are you located - I'm sure any good mechanic can diagnose the problems. These older V8's are pretty simple to work on. I have a great guy here in LA if you are local who has helped a ton with my old Unimog.
    Have you replaced the fuel injectors ?

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    Since you've checked the fueling and ignition, i say it's related to AFM sesnor. The plate shaped AFM in K-Jet system has always been a pain in the butt in those cars.

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