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engine not running smooth

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  • engine not running smooth

    after 3 weeks of not running the car.
    Started the car. started running, but rough, checked all the sparkplugs
    one was to rich( having this problem always) but after cleaning the
    sparkplugs same thing running rough( ALMOST like on 3 Zylinders)
    checked all connection from the 1/2/3 iginiton ok. then I checked the
    sparks with a inline ignition spark checker. on all zylinders same spark
    pretty regular. and often. so now what.?
    I have no Exhaust smoke, Could be a valve stuck??
    what else I should look for?
    PS. GOT A 1 3/4 sU ENGINE 1360

  • #2
    Peter, do a compression check. That could help you to isolate the problem. Low reading in one cylinder, could be a stuck valve(s) or piston rings shot. Low reading in two adjacent cylinders would point to a bad head gasket.


    • #3
      It is also possible that the fouled spark plug is still fouled even after cleaning. I have had plugs that were fuel fouled that wouldn't work even after cleaning. To clear them I heated the electrode / insulator with a propane torch to burn off the fuel. After that they worked.

      As Jerry suggests a compression test would be a good idea.

      If you can afford the car, you can afford the manual...


      • #4
        changed all 4 sparkplugs from:
        NGK Ridium BPR 6 eix to
        N9YC champion 300 + copper Bougies
        Car runs great.
        probably I had always the wrong plugs in the car.( because it was always running rich.
        any input regarding the different plugs.?


        • #5
          The NGK you have is a pretty fancy plug. Mini's usually don't need anything like that. The Champion is the plug the Mini probably shipped with when it was new.

          It's possible that since the NGK Ridium BPR 6 eix is a resistor plug (the R in BPR) it was causing a problem. Sometimes a resistor plug combined with resistor plug leads can cause weak spark and incomplete combustion. This can make it look like the mixture is rich. If you had resistor plugs, resistor leads and resistor plug caps I would be surprised if the car would run at all.

          If you can afford the car, you can afford the manual...


          • #6
            during our weekend trip to the Colombia River
            car was running great checked the plugs looked all good except no. 3
            a tiny bit rich., can live with it.