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    really weird issue

    So I did a bunch of work to my car I did the cooling system, mess under intake, timing system and added an SSSquid chip with some 4 pintle 19#injectors. Every thing was great car ran like a raped ape for 200+ miles my only issue was my lower timing cover gasket did seal for some reason so I had to replace it. After replacing the gasket I got it all back together and fired it up and it was absolutely horrible, The brake fluid, ABS and battery light all come on and stay on until I touch the throttle then they shut off regardless of throttle input it all idled like crap very low like 300 rpm. I checked the alt and the voltage regulator was weak so i put a new one in and still have the same issues. Then one day I was sitting in the car and held the rpm's to around 2500 and could smell something hot. I got out and my headers were cherry red and the car wasn't even at OP temp yet. I thought maybe my cat was plugged because after it did that i rolled down my drive way and tried to drive up it and the car wanted to go no where at all. I gutted out my cat because I don't have emissions here and that was simplest solution and still at my headers get red hot really fast and I have zero power. I checked my plugs and they are showing a lean mixture. I unplugged my cam sensor to make it run rich and this time my headers took a little longer to get hot but they still did. I ohm'd my crank sensor and my reading was .561 ohms and yet the car can still start? I really have no clue what is going on with this thing. Could my crank sensor be causing my ignition timing to be off causing the really lean mixture? There is no way my mechanical timing is off as I used proper tools the first time and got 200 amazing miles out of it before simply unplugging my cam and crank sensors and replacing the gaskets. I'm really scratching my head with this one. If you go off the theory of it has to be something i touched when doing gaskets then the cam and crank sensor are the only two things i touched that could cause this and my sensor is out of spec but I have never heard of a sensor doing this before and dont wanna shot gun the car with more parts i already put a ton of cash in it.

    edit: i should also add that a couple of times upon dropping the e brake my lights on the dash turned off I'm not sure if it was a coincidence or not


    1989 325is l 1984 euro 320i l 1970 2002 Racecar
    1991 318i 4dr slick top


    Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
    Vintage race car revival (2002 content)
    Mtech 2 turbo restoration
    Brilliantrot slick top "build"

    #2
    Verify the installation and condition of the alternator ground strap.

    Between which CPS pins did you read 0.561 Ohms? I agree that it seems like the car should not run at all if that sensor was toast since the timing would basically be random, and I think that the DME would cut fuel+ignition if it saw more or less than 58 teeth between the 2-tooth gap.

    This is a weird one. I could see the headers heating up like that from lean running due to a bad chip, but obviously that is not the case. Given all of the other electrical issues that are popping up, this seems like it could be a grounding problem somewhere. Maybe a strap got damaged? If the alternator or engine straps are broken, there are other paths for all of that current to go, but they are really not good paths since they are going to pose a high resistance.

    Rig up a multimeter so that its ground is connected to the battery's negative post, and then with the engine running probe around the engine bay with the positive lead. Specifically, see what the voltage is at the ground lug on the chassis ("battery tray" where the Motronic is grounded), on the engine itself (intake manifold?) and the alternator body if you can safely access it while it is running.

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      #3
      really weird issue

      Originally posted by bmwman91 View Post
      Verify the installation and condition of the alternator ground strap.



      Between which CPS pins did you read 0.561 Ohms? I agree that it seems like the car should not run at all if that sensor was toast since the timing would basically be random, and I think that the DME would cut fuel+ignition if it saw more or less than 58 teeth between the 2-tooth gap.



      This is a weird one. I could see the headers heating up like that from lean running due to a bad chip, but obviously that is not the case. Given all of the other electrical issues that are popping up, this seems like it could be a grounding problem somewhere. Maybe a strap got damaged? If the alternator or engine straps are broken, there are other paths for all of that current to go, but they are really not good paths since they are going to pose a high resistance.



      Rig up a multimeter so that its ground is connected to the battery's negative post, and then with the engine running probe around the engine bay with the positive lead. Specifically, see what the voltage is at the ground lug on the chassis ("battery tray" where the Motronic is grounded), on the engine itself (intake manifold?) and the alternator body if you can safely access it while it is running.


      I have tested all the grounds in the bay and none of them have a short. I did a continuity test and they all passed. I can try and see if can make some longer leads and do a voltage drop test on all the ground but i would think if they all had continuity they would be functioning.

      i tested pins 1-2 on the cps like the bentley stated. I made sure I was on 1-2 by doing 2-3 and that just read nothing not OL just contnuity


      The only other thing i think i might try and do is unplug the dme and plug it back in. On my chipped m30 car i was testing the afm and unplugged it and it ran extremely lean and couldn’t recover even after turning car off and restarting it. I unplugged the dme and plugged it back in and car ran fine again. Maybe unplugging the cam/crank sensor even with the car off screwed with the chip?
      Last edited by ThatOneEuroE30; 10-09-2017, 06:02 AM.


      1989 325is l 1984 euro 320i l 1970 2002 Racecar
      1991 318i 4dr slick top


      Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
      Vintage race car revival (2002 content)
      Mtech 2 turbo restoration
      Brilliantrot slick top "build"

      Comment


        #4
        There are some (small) alternate ground paths between the engine & chassis. With a multimeter they would not show up as being significant, but when the full current of the running engine is passing through them they can be a big problem.

        Yeah, might as well try resetting the ECU too. Are there any stored error codes?

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          #5
          Originally posted by bmwman91 View Post
          There are some (small) alternate ground paths between the engine & chassis. With a multimeter they would not show up as being significant, but when the full current of the running engine is passing through them they can be a big problem.

          Yeah, might as well try resetting the ECU too. Are there any stored error codes?
          No stored error codes the CE light hasnt came on except for when it stalled once. I was talking with an instructor at school this morning he told me to check my fuel pressure and to try and unplug the 02 sensor and see what happens. He thinks it could be stuck in full rich and even at first start up so the DME is taking all the fuel away. Also told me to check the AFM. I really need to buy a lab scope to see what things are doing.


          1989 325is l 1984 euro 320i l 1970 2002 Racecar
          1991 318i 4dr slick top


          Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
          Vintage race car revival (2002 content)
          Mtech 2 turbo restoration
          Brilliantrot slick top "build"

          Comment


            #6
            Hey bud,

            you may want to do a continuity test between some positive terminals and the ground terminals-- the grounds may be well connected, but a loose positive terminal/wire may be making contact with a grounded area as well.

            Another thing to note is that I've seen a few of these M42 ECUs blow out their coil driver in the ECU. You can usually see some white and/or black discoloration around the up-right heat-sinks on the sides of the PCB.

            Let me know!

            Comment


              #7
              Originally posted by squidmaster View Post
              Hey bud,

              you may want to do a continuity test between some positive terminals and the ground terminals-- the grounds may be well connected, but a loose positive terminal/wire may be making contact with a grounded area as well.

              Another thing to note is that I've seen a few of these M42 ECUs blow out their coil driver in the ECU. You can usually see some white and/or black discoloration around the up-right heat-sinks on the sides of the PCB.

              Let me know!
              so your saying to take the ecu apart and make sure nothing is burnt up in it and to take the DMM and put one lead onto the positive terminal on the junction box on battery tray and then the engine ground straps?


              1989 325is l 1984 euro 320i l 1970 2002 Racecar
              1991 318i 4dr slick top


              Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
              Vintage race car revival (2002 content)
              Mtech 2 turbo restoration
              Brilliantrot slick top "build"

              Comment


                #8
                Yep! Test out the grounding areas against a battery lead wire and see if any give you a beep (or have a very low ohm rating).

                There was another thread with a member that had a burnt-out driver recently, but I can't find it in my subscribed. If it pops up again, I'll post it here.

                Comment


                  #9
                  so I unplugged the o2 sensor and still had same result. I moved to the fuel pressure test and at idle my gauge read 36-38 psi unload it bounce around from there to 44 psi. So that leads me to believe its got good fuel pressure? next thing on the list is it check the power to grounds and then pull the ecu


                  1989 325is l 1984 euro 320i l 1970 2002 Racecar
                  1991 318i 4dr slick top


                  Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                  Vintage race car revival (2002 content)
                  Mtech 2 turbo restoration
                  Brilliantrot slick top "build"

                  Comment


                    #10
                    put one lead on the junction box and touched it to the main engine ground strap and got nothing. I touched it to the box and the grounding point on the battery tray and got nothing. I touched it to the box and alt ground and got nothing to make sure i was getting through I touched my main battery terminal to the fusible link and got continuity


                    1989 325is l 1984 euro 320i l 1970 2002 Racecar
                    1991 318i 4dr slick top


                    Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                    Vintage race car revival (2002 content)
                    Mtech 2 turbo restoration
                    Brilliantrot slick top "build"

                    Comment


                      #11
                      Ecu looked fine. board had a little discoloration but nothing that indicated a short or anything or so i think. I'm done with this thing for the day or week.


                      1989 325is l 1984 euro 320i l 1970 2002 Racecar
                      1991 318i 4dr slick top


                      Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                      Vintage race car revival (2002 content)
                      Mtech 2 turbo restoration
                      Brilliantrot slick top "build"

                      Comment


                        #12
                        Is there any way that the muffler got clogged somehow? Like a loose baffle, or chunk of cat core?

                        I say pull the cat back and see how it runs. I will tell you from experience that it sounds...amazing (?)! And that was WITH a functional cat! Your neighbors will thank you...

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                          #13
                          really weird issue

                          Originally posted by bmwman91 View Post
                          Is there any way that the muffler got clogged somehow? Like a loose baffle, or chunk of cat core?


                          I have checked the muffler and it looks clear. Its a brand new Strömung unit. From what i can tell when i gutted the cat it was all intact and nothing came apart and got lodged in the piping. I have a scope i can shove down the muffler and see if there is anything


                          Is it possible a faulty AFM could have the engine running full lean?


                          1989 325is l 1984 euro 320i l 1970 2002 Racecar
                          1991 318i 4dr slick top


                          Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                          Vintage race car revival (2002 content)
                          Mtech 2 turbo restoration
                          Brilliantrot slick top "build"

                          Comment


                            #14
                            Wondering if i shouldnt order this lab scope to try and diagnose the issue. Seems like it could help rule things out.



                            1989 325is l 1984 euro 320i l 1970 2002 Racecar
                            1991 318i 4dr slick top


                            Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                            Vintage race car revival (2002 content)
                            Mtech 2 turbo restoration
                            Brilliantrot slick top "build"

                            Comment


                              #15
                              turns out its my AFM its not getting any continuity through the veins range of motion i ran the car with it unplugged the idle was great and the lights went off i did it 3 times to be sure. it does fall on its face at 1500 rpm but Im willing to bet that's from the chip and lack of fuel mixture reading


                              1989 325is l 1984 euro 320i l 1970 2002 Racecar
                              1991 318i 4dr slick top


                              Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
                              Vintage race car revival (2002 content)
                              Mtech 2 turbo restoration
                              Brilliantrot slick top "build"

                              Comment

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