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Need R3v gurus, 1 or 2 cylinders running rich, Hesitation below 4k, out of ideas

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    Need R3v gurus, 1 or 2 cylinders running rich, Hesitation below 4k, out of ideas

    I'm trying to figure out what would cause one or two cylinders to run rich in my OBD1 S52. Been chasing a problem for months with hesitation until 4k rpms and done about everything i can think of, one thing that hasnt changed is cylinder 6 spark plug shows rich condition and cylinder 4 looks a tad rich but not as much



    Things to note:

    -Compression check good (less than 5 psi difference across all cylinders)

    -leakdown provided no answer, everything good with nothing out of the ordinary

    -checked for vacuum leaks multiple times, home made smoke test and essentially dousing everything in carb cleaner showed nothing

    -replaced maf

    -rebuilt vanos

    -replaced crank and cam position sensor

    -replaced coolant temp sensor

    -replaced intake temp sensor

    -replaced injectors twice (both new sets)

    -replaced and swapped around coil packs (no change regardless)

    -replaced spark plugs twice (both new, checked gap each time)

    -replaced fuel pump, filter, and FPR

    -replaced o2 sensor (have a new bosch sensor to try too)

    -replaced ecu

    -installed new sssquid chip

    -tried different known good ICV

    -tried different known good

    -replaced battery



    basically everything electronic and fuel related has been replaced and mechanically the engine seems great, just not under 4k. after a battery reset the idle searches and will dip when coming to a stop until after some time learning. then from a stop and cruising it hesitates and bucks until above 4k. i initially thought is was the vanos but after a rebuild the problem still exists. it seems like the initial battery reset idle problem and the hesitation are related but not 100% on that. its awesome above 4k but cruising on the highway and from a stop its terrible



    i need the r3v gurus help on this, im about to hesitate this POS into a wall. the only thing electronic left to replace is the knock sensors and the wiring harness (which i have both) but was wondering if anyone had any input.



    spark plug picture and video will be in next post



    update: redid timing and main exhaust sprocket seemed off a tooth so moved it according to the pelican procedure and now all are rich, still has hesitation
    Last edited by Sladek; 10-31-2017, 04:22 PM.

    #2
    Need R3v gurus, 1 or 2 cylinders running rich, Hesitation below 4k, out of ideas


    cylinder 1>>>cylinder 6

    more used set up front, newer set in background

    Comment


      #3




      both of these were going WOT from cruising. the first video it's hard to hear but watching the tach stay still it's hesitating the whole time and then finally starts accelerating. the second one is a short buck.

      hard to get a video from a stop

      Comment


        #4
        My initial reaction is to flow test your injectors.
        4 and 6 look rich, which really means 5 is lean...

        <edit, well, wait, if you've swapped them and that pattern persists, I'm wrong about that>

        I've been messing around with m54s too much recently, but if the cam position sensor is
        inaccurate (like, maybe out of phase? I'm really guessing here) would THAT mess up how
        the ECU is trying to match flows on individual injectors???

        fwiw,

        t
        Last edited by TobyB; 10-04-2017, 05:23 PM.
        now, sometimes I just mess with people. It's more entertaining that way. george graves

        Comment


          #5
          Originally posted by TobyB View Post
          My initial reaction is to flow test your injectors.
          4 and 6 look rich, which really means 5 is lean...

          <edit, well, wait, if you've swapped them and that pattern persists, I'm wrong about that>

          I've been messing around with m54s too much recently, but if the cam position sensor is
          inaccurate (like, maybe out of phase? I'm really guessing here) would THAT mess up how
          the ECU is trying to match flows on individual injectors???

          fwiw,

          t
          yeah both sets of injectors are new and flow matched, but i do wonder if maybe timing/cam phasing is off slightly and thats causing some sort of issue, if that would even be a symptom

          Comment


            #6
            anyone else have any ideas?

            Comment


              #7
              redid the timing, seemed like main exhaust sprocket was off one tooth (slots were in the middle and adjusted to the left like in the pelican article)

              still runs like crap under 4k but now all the cylinders are running super rich. still searches for idle when clutch in coming to a stop or if i blip the throttle while sitting itll search before settling in a 1000 to 1100rpms which seems high to me

              Comment


                #8
                Are you using BMW OEM CPS and cam sensors ?
                My CA legal M60 swap

                The happening in our garage

                Comment


                  #9
                  Originally posted by 36brua View Post
                  Are you using BMW OEM CPS and cam sensors ?
                  yep, straight from fcpeuro

                  Comment


                    #10
                    when you turn the ignition on to run but do not crank it. Can you hear an injector click and fire off? As in squirting fuel?



                    Comment


                      #11
                      Originally posted by ZekeTheSneak View Post
                      when you turn the ignition on to run but do not crank it. Can you hear an injector click and fire off? As in squirting fuel?


                      hard to say sitting in the car, should I? starting isn't so much of a problem as much as the hesitation and running rich. I don't think they are stuck open either

                      Comment


                        #12
                        No they shouldn't click with the key turned into the on position. But if they do click then the dme injector controller died. Happened to me. It like flooded the cylinder though. Gas was pouring out of the exhaust



                        Comment


                          #13
                          Originally posted by ZekeTheSneak View Post
                          No they shouldn't click with the key turned into the on position. But if they do click then the dme injector controller died. Happened to me. It like flooded the cylinder though. Gas was pouring out of the exhaust
                          i guess ill check that out. ive changed the DME out so i doubt it would happen on both unless something is frying it with wiring. cant hurt to check

                          Comment

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