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  • Motronic Sensor Signals

    Been wanting to do this for ages, and finally found the motivation tonight... Hopefully a useful reference for others when needing to check sensors. I'll add this info to s2central.net when time permits, but here goes...

    All taken at warm idle (approx 800rpm) and the timing lines up with my sums which is a relief... 135 flywheel teeth and therefore 150ms 4-stroke cycle time => all cyls go thru four strokes in that time.
    Attached Files
    Paul Nugent
    Webmaster http://S2central.net
    Administrator http://S2forum.com

    1994 S2 Coupe ABY - aka Project Lazarus
    2001 A6 allroad 2.5TDi - family tank
    2003 S4 Avant 4.2 V8 - daily burble

    Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

    There are only 10 kinds of people that understand binary - those that do, and those that don't

  • #2
    Sweet Paul but what sensors give each pulse...
    Cheers'en, AndyC
    1994 ABY Coupe - Projekt Alpinweiss

    Comment


    • #3
      The scope I have isn't deadly accurate and the revs wont have been exactly 800rpm but its all in the realms of tolerance and darn good sanity check...

      The coil trigger period is ~150ms and its pulse voltage from the ECU is approx 3V. This is input signal to the POS unit.

      The CMP voltage from hall sensor is a -ve pulse of approx 5V amplitude. Its width is approx 8ms... I assume its always that wide.

      Note how in 06 the CPS pulse slices the CMP in half - that was a surprise but its a good idea.


      NOTE - This is for a DI engine (ABY) - EACH coil fires every 150ms at idle... But on a 3B engine the coil will be firing every 30ms and the dissy doing its whizzy round thing of asking sparks to jump to the right place at the right time (hopefully).
      Attached Files
      Paul Nugent
      Webmaster http://S2central.net
      Administrator http://S2forum.com

      1994 S2 Coupe ABY - aka Project Lazarus
      2001 A6 allroad 2.5TDi - family tank
      2003 S4 Avant 4.2 V8 - daily burble

      Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

      There are only 10 kinds of people that understand binary - those that do, and those that don't

      Comment


      • #4
        Originally posted by Andy_Casey View Post
        Sweet Paul but what sensors give each pulse...
        The secret is in the name...

        G4 - CPS => Crankshaft Position Sensor. This is a reference pulse 62 deg BTDC on #1

        G28- RPM => Crankshaft speed... Driven by flywheel teeth

        G40- CMP => Camshaft Position (Hall Sender) - A reference signal needed by ECU to determine when #1 is on the firing stroke - it cant tell that from G4 alone !
        Paul Nugent
        Webmaster http://S2central.net
        Administrator http://S2forum.com

        1994 S2 Coupe ABY - aka Project Lazarus
        2001 A6 allroad 2.5TDi - family tank
        2003 S4 Avant 4.2 V8 - daily burble

        Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

        There are only 10 kinds of people that understand binary - those that do, and those that don't

        Comment


        • #5
          Sweet, missed them as they're a tiny subscript to the sexy signal pics
          Cheers'en, AndyC
          1994 ABY Coupe - Projekt Alpinweiss

          Comment


          • #6
            For anyone that wants to do the math on checking signal timings at higher engine speeds...

            Take the RPM value (crankshaft) and divide that by 2 for camshaft rpm. Then multiply that by 5 for number of sparks per minute... and divide that by 60 for sparks per second we can call 'S'

            Then its (1000/S) multiplied by the number of coils you have to determine the gap (in milliseconds) between the sparks on each coil.

            On the DI engines its 150ms at 800rpm and 15ms at 8000rpm
            On the 3B engine the inter-spark times are five times faster so its easy to see why that single coil gets stressed - having to fire every 3ms at 8000rpm (or 333 times a second if you prefer).


            Paul
            Paul Nugent
            Webmaster http://S2central.net
            Administrator http://S2forum.com

            1994 S2 Coupe ABY - aka Project Lazarus
            2001 A6 allroad 2.5TDi - family tank
            2003 S4 Avant 4.2 V8 - daily burble

            Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

            There are only 10 kinds of people that understand binary - those that do, and those that don't

            Comment


            • #7
              The injector pulse is 2.4 ms at idle on rs2 injectors. Nice 12v pulse. Found that out while setting up the gas. Paul i have a 4 channel coulor scope if you want to get real adventurous..

              Comment


              • #8
                @Des - you could be my best friend ever with a few hours access to that scope...

                I went a bit bonkers trying to chase multiple signals on a single channel - I'm maxxed out however on time for a few weeks - we should try and sync up in 2nd half of August if that works for you - I still have some tweaking to do on those chips for you if you can trundle up to fit the bigger injectors.
                Paul Nugent
                Webmaster http://S2central.net
                Administrator http://S2forum.com

                1994 S2 Coupe ABY - aka Project Lazarus
                2001 A6 allroad 2.5TDi - family tank
                2003 S4 Avant 4.2 V8 - daily burble

                Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                There are only 10 kinds of people that understand binary - those that do, and those that don't

                Comment


                • #9
                  Pico Scope Information

                  I receive updates/information from Pico Scope on a regular basis and the following will be of intrest to you. Enjoy.

                  http://www.picoauto.com/tutorials/audi.html?A080701
                  "Nulla tenaci invia est via"

                  Comment


                  • #10
                    No problem Paul. Give me a shout when your free and i can leave the scope with you for a week or so. Must order a set of bigger injectors about 550 cc. ok? Cheers,des.

                    Comment


                    • #11
                      @Des - 550cc on 4bar is bound to be enough... You still have that AFR gauge installed dont you - we're sure gonna need it.

                      @Qship - good article though I'm sure I saw it years ago and was utterly clueless then as to the importance of those waveforms... They check out with my findings in terms of waveform shape and timing. I'll have to get more scope time to measure the hall window more accurately... I have it at approx 8-10ms at 800rpm which broadly aligns with their statement of approx 46 crank teeth.
                      Paul Nugent
                      Webmaster http://S2central.net
                      Administrator http://S2forum.com

                      1994 S2 Coupe ABY - aka Project Lazarus
                      2001 A6 allroad 2.5TDi - family tank
                      2003 S4 Avant 4.2 V8 - daily burble

                      Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                      There are only 10 kinds of people that understand binary - those that do, and those that don't

                      Comment


                      • #12
                        Injectors ordered..... Yep AFR installed

                        Comment


                        • #13
                          Is that a rising edge signal on the crank postion sensor? Fairly sure it is. Cheers for any input.

                          jure
                          Last edited by jure; 8 September 2010, 15:04.

                          Comment


                          • #14
                            Its both actually on G4... The negative pulse comes first though. Overall duration is very short as you can see.
                            Paul Nugent
                            Webmaster http://S2central.net
                            Administrator http://S2forum.com

                            1994 S2 Coupe ABY - aka Project Lazarus
                            2001 A6 allroad 2.5TDi - family tank
                            2003 S4 Avant 4.2 V8 - daily burble

                            Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                            There are only 10 kinds of people that understand binary - those that do, and those that don't

                            Comment


                            • #15
                              Due to popular demand... Some more insight and capture on this one.

                              The drawing and traces in this short document will help anyone diagnose all sorts of strange sensor faults and no-start problems, but you NEED at least a two channel scope to do this properly.
                              Attached Files
                              Paul Nugent
                              Webmaster http://S2central.net
                              Administrator http://S2forum.com

                              1994 S2 Coupe ABY - aka Project Lazarus
                              2001 A6 allroad 2.5TDi - family tank
                              2003 S4 Avant 4.2 V8 - daily burble

                              Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                              There are only 10 kinds of people that understand binary - those that do, and those that don't

                              Comment

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