Announcement

Collapse
No announcement yet.

NO START HELP (2nd page) and higher load/higher rpm feels like rev limiter

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    NO START HELP (2nd page) and higher load/higher rpm feels like rev limiter

    .

    SEE POST #15 BELOW FOR NEW ISSUE - CPS did fix some issues..

    Like the title says, I bought a brand new Facet CPS from pelican.

    Measured with a very accurate Fluke multimeter, I found the resistance across pins 1 and 2 to be 609 ohms, which is out of spec (540+/- 54)



    The only reason I see this being a possible issue is that the tooth logger on megasquirt is showing randomly missed tooth pulses, which in turn causes misfires. This is prominently seen under load and higher RPMs (above ~2500)


    Do I buy an OEM one? I'd rather not throw parts at the issue.



    .
    Last edited by saturnv7890; 07-03-2013, 06:53 AM.

    My Transaction Feedback
    My "build" thread
    BUY MY CAR!!

    #2
    I've had issues with aftermarket crank sensors as well. I recommend buying OEM BMW.
    BimmerHeads
    Classic BMW Specialists
    Santa Clarita, CA

    www.BimmerHeads.com

    Comment


      #3
      The OE or OEM part only.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

      Comment


        #4
        Yeahh I'm shooting good old blunttech an email now. Thanks! I'll post results if anything changes

        My Transaction Feedback
        My "build" thread
        BUY MY CAR!!

        Comment


          #5
          I should have also mentioned... A bad engine harness (degradation of the CPS coax in the harness) can also cause what you are seeing. Try an OE CPS first, but if the fault persists, change the engine harness. If that turns out to be the problem you may have better luck than me. But I went through three used harnesses on my Spec E30 solving the same problem before totally fixing it by getting a new harness from BMW (~$800).
          The car makes it possible, but the driver makes it happen.
          Jim Levie, Huntsville, AL

          Comment


            #6
            Seems a bit drastic to change out an entire engine harness. Why not just change out the shielded wire that runs from the CPS to the ecu?


            Also, I noticed the misfiring isn't a problem for the first ~20-30 minutes of driving, it only starts to miss more under load and high rpms after it's been running for a while. I see RPM spikes on my datalog

            My Transaction Feedback
            My "build" thread
            BUY MY CAR!!

            Comment


              #7
              Originally posted by saturnv7890 View Post
              Seems a bit drastic to change out an entire engine harness. Why not just change out the shielded wire that runs from the CPS to the ecu?
              If the coax for the CPS is degraded, the rest of the wiring in the harness won't be in much better condition. And the harness has to be cut open to replace the coax. I did that on the last used harness. It fixed the timing data problem, but two race weekends later it developed problems with the AFM and ECT signals. So I "bit the bullet" and ordered a new harness.
              Also, I noticed the misfiring isn't a problem for the first ~20-30 minutes of driving, it only starts to miss more under load and high rpms after it's been running for a while. I see RPM spikes on my datalog
              Harness problems can be intermittent and can be heat related.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

              Comment


                #8
                Originally posted by jlevie View Post
                If the coax for the CPS is degraded, the rest of the wiring in the harness won't be in much better condition. And the harness has to be cut open to replace the coax. I did that on the last used harness. It fixed the timing data problem, but two race weekends later it developed problems with the AFM and ECT signals. So I "bit the bullet" and ordered a new harness.

                Harness problems can be intermittent and can be heat related.
                Well that is just terrible haha. I think all my other signals are reading fine right now though. Luckily with megasquirt I don't have an AFM. I might give it a try with some new shielded wire for now.

                Can you comment on the quality of Vemo brand? Blunttech is saying vemo is fine, it's facet that you want to avoid (which I currently have)

                I can get a vemo tomorrow locally, or wait a few days for the OEM one to ship from bmw. Problem is I need my car :/

                My Transaction Feedback
                My "build" thread
                BUY MY CAR!!

                Comment


                  #9
                  Personally I only use the genuine BMW part RM European probably has it in stock. Or you can get it from your dealer in a few days.
                  The car makes it possible, but the driver makes it happen.
                  Jim Levie, Huntsville, AL

                  Comment


                    #10
                    Well I changed up the wiring and it's still missing like crazy under any load and higher rpms. This does sound like a cps issue right?

                    My ignition system is in perfect shape otherwise

                    My Transaction Feedback
                    My "build" thread
                    BUY MY CAR!!

                    Comment


                      #11
                      Are you still seeing timing data drops in the MS logs? Have you replaced the CPS with a BMW part?
                      The car makes it possible, but the driver makes it happen.
                      Jim Levie, Huntsville, AL

                      Comment


                        #12
                        I am seeing timing data drops, and I just ordered a BMW cps. I didn't want to jump right in to throwing expensive parts at the issue, I've learned my lesson a long time ago not to do that. So I guess all I can do now is sit around waiting for the part to come in?

                        Is there anything else I could try?

                        My Transaction Feedback
                        My "build" thread
                        BUY MY CAR!!

                        Comment


                          #13
                          Nope.
                          The car makes it possible, but the driver makes it happen.
                          Jim Levie, Huntsville, AL

                          Comment


                            #14
                            Well I guess I'll hope for the best then!

                            I'll post results tuesday when the part comes in, blunt's got a warehouse close by!

                            My Transaction Feedback
                            My "build" thread
                            BUY MY CAR!!

                            Comment


                              #15
                              Fixed the low rpm/random/constant bucking I've been having, the car now accelerates smooth when being gentle on the throttle, and it'll accelerate smooth until about 3500 now.

                              But above that, and with any heavy throttle, the car will start shuddering and not accelerating as fast. At higher rpms in to boost, the car will cut in and out like it's hitting a rev limiter.



                              New ideas? I don't think it's running lean, at least the wideband isn't saying lean.


                              Looked at log: when it starts to buck I think it may start to err towards lean but then it goes right back to an acceptable level? Or maybe i'm seeing the wrong point, and it actually went rich.

                              Do fouled spark plugs cause this behavior so violently and consisently? EDIT: spark plugs are not fouled.


                              Could it still be my CPS??


                              The car is relaly hard starting now, not sure why
                              Last edited by saturnv7890; 07-03-2013, 05:32 PM.

                              My Transaction Feedback
                              My "build" thread
                              BUY MY CAR!!

                              Comment

                              Working...
                              X