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took video of my M20's idle for some help

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    took video of my M20's idle for some help

    here is what my 3 sounds like when it idles - almost makes me think its running on 5 cylinders or something


    I don't really know what this is, I have looked at a ton of threads and found some similar to my problem but none have been a dead-on match

    when I cold start it, it takes a little longer than normal to start up cold than my 89 and it sometimes can catch itself before it dies to idle but most of the time it just goes right to idle at about 600 rpm.

    when I warm start it, it cranks for a good 20 seconds before it will start up, it will cough a little before it starts right up

    when it starts, it will run no matter what till you turn it off, just as rough in neutral as it is in drive.

    the engine runs very well above 1,200 rpm but not below

    the CEL comes on below 1,000 rpm probably due to low engine speed but goes right off. above 1,000, its off 100% of the time.

    seems to get worse than average MPG but not too bad.

    the hoses I have checked look like they are in good shape but I haven't checked/cleaned the CSV, plugs etc.

    any ideas?
    1991 E30 M3 Brilliant/black - S54B32/5M
    1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
    2011 E82 1M VO/blk/6M
    1991 E31 850i red/grey/6M
    1997 F355 spider red/tan/6M

    #2
    kinda sounds like a missfire to me. check all your spark plugs and check the spark plug wires.
    :borg:

    Comment


      #3
      will do, may as well just get some new ones, I have no idea the extent this car has been neglected

      what does BMW recommend as far as plug?

      I use champion non-resistor copper core plugs in my benzies and they do wonders, whats the correct gap?
      1991 E30 M3 Brilliant/black - S54B32/5M
      1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
      2011 E82 1M VO/blk/6M
      1991 E31 850i red/grey/6M
      1997 F355 spider red/tan/6M

      Comment


        #4
        Does it stutter/hesitate when you give it gas at low rpm?

        Comment


          #5
          Originally posted by Wh33lhop View Post
          Does it stutter/hesitate when you give it gas at low rpm?
          maybe below 1,200rpm when its running rough and I accelerate it does, but after that it runs perfect.
          1991 E30 M3 Brilliant/black - S54B32/5M
          1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
          2011 E82 1M VO/blk/6M
          1991 E31 850i red/grey/6M
          1997 F355 spider red/tan/6M

          Comment


            #6
            replaced the plugs, runs the same as before which is amazing because the old plugs looked horrible.



            it may have loss of power, I dont know though since its been idling rough since I bought it,

            next thing to check?
            Last edited by 2.5-12; 02-05-2010, 04:52 PM.
            1991 E30 M3 Brilliant/black - S54B32/5M
            1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
            2011 E82 1M VO/blk/6M
            1991 E31 850i red/grey/6M
            1997 F355 spider red/tan/6M

            Comment


              #7
              did you get a chance to check the plug wires too ? look for corrosion on the connections. and if you have a digital multimeter check the resistance in the wires should be about 5000 +/- 1000 ohms i would also check to make sure each plug is getting spak.
              :borg:

              Comment


                #8
                Originally posted by !kid View Post
                did you get a chance to check the plug wires too ? look for corrosion on the connections. and if you have a digital multimeter check the resistance in the wires should be about 5000 +/- 1000 ohms i would also check to make sure each plug is getting spak.
                I didnt have my miltimiter with me, I'll make sure to check the wires tomorrow

                do I just pop a used plug into each one while the engine is running and check for spark?

                sorry for the noobness :)
                1991 E30 M3 Brilliant/black - S54B32/5M
                1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
                2011 E82 1M VO/blk/6M
                1991 E31 850i red/grey/6M
                1997 F355 spider red/tan/6M

                Comment


                  #9
                  yeah, just plug in a old plug and set it on the valve cover or somthing metel that has ground. have someone crank the motor while you watch for a spark. do this for each cylinder. so what kinda plugs did you go with? i think most guys run NGK BPR5ES or Bosch W8LCR

                  the Bentley repair manual says to use Bosch W8LCR with a .027 gap
                  Last edited by !kid; 02-05-2010, 08:46 PM.
                  :borg:

                  Comment


                    #10
                    I went with MB OEM Champion non-resistor copper core plugs with a 28/1000ths gap

                    I'll check for spark tomorrow

                    the car wont even stay running on its own when its cold with the new plugs now, lol

                    my CEL comes on a lot more now too. runs better when its warm now though, but by much, but its different.
                    1991 E30 M3 Brilliant/black - S54B32/5M
                    1990 E30 318iT RHD Lagunagrun/tan - S52B32Turbo/5M
                    2011 E82 1M VO/blk/6M
                    1991 E31 850i red/grey/6M
                    1997 F355 spider red/tan/6M

                    Comment


                      #11
                      low idle and hard starting problems u mentioned sounds like the ICV might be sticking or past its sell by date.

                      Currently E30-less

                      - EthosMotorsports.com

                      Comment


                        #12
                        vaccum leak. find it, fix it, and your problems will be gone. that is not a misfire problem.
                        90 E30 325i

                        Comment


                          #13
                          Probably a vacuum leak. Grab a can of starting fluid and start spraying different parts of the engine and listen for the rpms to climb. When you spray an area that's leaking, it will pull the starting fluid in and the rpms will jump a bit. Check around the AFM, throttle body, intake boot, manifold where it mates to the head, fuel injector seats, breather tube from the block to the underside of the TB, etc.

                          There's also a possibility of a fouled injector, bad wires, or maybe even a bad cap or rotor. But I'd start with the vacuum leak.

                          Comment


                            #14
                            How come noone ever suggest a bad crank sensor? Does your car buck at all? I found my problem to be that my CS wire was sliced open and still managed to turn my car on.
                            @IRON-E30 aka Edwin:D

                            Comment


                              #15
                              Originally posted by IRON-E View Post
                              How come noone ever suggest a bad crank sensor? Does your car buck at all? I found my problem to be that my CS wire was sliced open and still managed to turn my car on.
                              cuz its probably a vacuum leak.
                              90 E30 325i

                              Comment

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