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M52B28, S50us Cam Swapped, Surging/Misfire when Cold

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    M52B28, S50us Cam Swapped, Surging/Misfire when Cold

    Hi all,

    Really not sure where to go with this issue, everything is lining up towards being vanos related. I installed the S50 cams into my M52 with all the correct tools bar the cam hold down. The cam swap went well, was daunting but managed it just fine.

    Timing the motor, I have an m20 flywheel so I wasn't able to use a flywheel lock, but engine at TDC and cam locks sitting flush. Dummy tensioner was installed to the 1nm spec. Secondary chain and sprockets had full travel, I've redone the vanos install 3 times now (first two times I was getting the 212 vanos jammed error, I believe I was pulling the exhaust sprocket down way too far, doing so after the vanos gear had caught), catches on the first tooth.

    When I first start the car, it idles pretty flat, but ranges from somewhat lumpy to quite smooth randomly? When it is cold, it seems to drive fine without any hesitation or noticeable surge. However, on one occasion I had some pretty solid surging and pretty rapid (think popcorn limiter sounding) misfire.

    When the cars warm, it runs fine. There is a drop in torque down low, but up top it does run pretty well. I managed to run a datalog with a good 15 minute drive, nothing to suggest it wasn't running right. Upon reviewing the logs I did notice a drop in the load value compared to previous logs with M52 cams, part of me thinks the vanos isn't really doing anything then.

    I was concerned that I had maybe screwed up the cam install / timing, I checked compression and had all cylinders except cyl5 at 175psi, cyl5 read 170psi, which isn't really concerning at all.

    To me all fingers seem to point at two possibilities, first being timing is off and if so, only quite marginally. Second being that my vanos unit is stuffed, the seal is either gone or I've installed it incorrectly (I really doubt this scenario).

    Currently the car is showing no codes either, previously it had shown a mechanically jammed vanos unit code 212.

    I suppose the summary of this post is really just to confirm whether or not the issues that I have are related to vanos/Timing based on someone else's experience / knowledge? As always, any help would be appreciated, I have been digging through pretty much all posts that relate to this issue, my 'symptoms' seem to be quite different to others.
    IG: https://www.instagram.com/josh.stacey/
    Flickr: https://www.flickr.com/photos/133952286@N03/

    #2
    I've just purchased a compressor fitting so I can test the vanos with air. Unless someone has other suggestions I'll test the unit and report back.
    IG: https://www.instagram.com/josh.stacey/
    Flickr: https://www.flickr.com/photos/133952286@N03/

    Comment


      #3
      The s52 cams need modified vanos maps to work correctly. The stock maps don't work well. Also that vanos jammed code could be because leaky vanos seals. Get new beisan vanos seals if you haven't changed those.

      Comment


        #4
        Originally posted by pazi88 View Post
        The s52 cams need modified vanos maps to work correctly. The stock maps don't work well. Also that vanos jammed code could be because leaky vanos seals. Get new beisan vanos seals if you haven't changed those.
        Yeah ordered a kit tonight, was really hoping to take it to track event this week, looks like that wont be happening then. I will do the compressed air method to test tomorrow night, I've got two spare vanos units that I can try to throw together while I wait for seals to arrive.
        IG: https://www.instagram.com/josh.stacey/
        Flickr: https://www.flickr.com/photos/133952286@N03/

        Comment


          #5
          Could also be a bad solenoid. Or maybe you installed the spring on the wrong side of the shuttle valve? I did that once. Basically makes the vanos stay on all the time.

          Comment


            #6
            did you get a new tune for the cams?
            www.cp-e.com

            1989 Zinno 325i m52 turbo coupe
            2015 Ford Fiesta ST, Daily Driver.

            Comment


              #7
              Originally posted by AndrewBird View Post
              Could also be a bad solenoid. Or maybe you installed the spring on the wrong side of the shuttle valve? I did that once. Basically makes the vanos stay on all the time.
              Both will throw fault code. First step in every m5x engine diagnostic is to start inpa and read fault codes.

              Comment


                #8
                No error codes showing in Inpa, https://datazap.me/u/jsta282/vanos-s...=2-5&mark=2351 datalog here.

                Did hook the air compressor up to the vanos unit and saw over 8.5mm travel.

                No I haven't got a tune. Plan was to do it myself, but I would like to think it should drive somewhat well enough prior to tuning.
                IG: https://www.instagram.com/josh.stacey/
                Flickr: https://www.flickr.com/photos/133952286@N03/

                Comment


                  #9
                  Without a tune, it's going run run like poo. I'd start there.

                  Comment


                    #10
                    Just for future reference for any one coming across this thread. Issue was fixed with adjusting the tune. As it turns out, vanos is working just fine (still going to rebuild it, as I've ordered the kit).

                    Initially my adaptions weren't working due to me unplugging the IAT sensor and not clearing the code (plugged in again now).

                    Once the lambda's kicked in (the car was running fine warm, this is why), the adaptions went and maxed out to be richer, this threw an error. To me it seemed like this was a vacuum leak, but I tested it all by pressurizing the intake and spraying soapy water and listening out for hissing. I found a few very small leaks and one hairline crack in the valve cover.

                    After sorting the small vacuum leaks, I decided to bump up the base fuel map to just see how things went. I added 0.20ms to the idle portion. Straight away on a dead cold start, idle quality was drastically improved, once lambdas kicked in adaptions were floating around 0.05ms.

                    Driving around my multiplicative adaptions have added about 3% into the map, car is driving a lot nicer now.

                    Also bumped vanos switch point to 5100rpm.

                    I've purchased and installed a wideband to help fine tune even further as well.

                    So to conclude, you "can" run S50/S52 cams on a stock M52B28 running OBD2, IF your adaptions are working (no codes stored). This map is less than ideal, to benefit from the swap either tune yourself or buy a tune.
                    IG: https://www.instagram.com/josh.stacey/
                    Flickr: https://www.flickr.com/photos/133952286@N03/

                    Comment


                      #11
                      I've had the "vanos mechanically jammed" code trigger from a bad cam sensor. Easy to unplug the connector under the intake, then pull back the boot to see if the wires have shed their insulation and are grounding out against each other.
                      Originally posted by priapism
                      My girl don't know shit, but she bakes a mean cupcake.
                      Originally posted by shameson
                      Usually it's best not to know how much money you have into your e30

                      Comment


                        #12
                        Originally posted by Northern View Post
                        I've had the "vanos mechanically jammed" code trigger from a bad cam sensor. Easy to unplug the connector under the intake, then pull back the boot to see if the wires have shed their insulation and are grounding out against each other.


                        Went through that pain when I first swapped the engine, cam sensor is relatively new and known working. INPA values fluctuate from 15 degrees at idle, 44-45 when vanos kicks on which fits the 30 crank degree window that vanos operates in.
                        IG: https://www.instagram.com/josh.stacey/
                        Flickr: https://www.flickr.com/photos/133952286@N03/

                        Comment


                          #13
                          Yeah for the cam sensor issue, stay away from any other cam sensor than "siemens" branded OEM sensor. The single vanos m52 cam sensor is weird oddball that no aftermarket manufacturer seems to know how to make working one. Because it's not standard hall or vr type sensor. And bad thing in those siemens sensors is that the wire insulation disintegrate over time.... Otherwise the siemens ms41 ecu is great piece of old technology.

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