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  • 20vQC
    S2Forum Maniac
    • Aug 2007
    • 684
    • Current: Italy

    #1

    On Board Trip Computer

    Hey mates! hope everything's fine! Well my ecu has been repaired and hopefully the 1st fire-up of the AAN will be this week! As I'm runining a stand alone, I did the very huuuuge mistake of cutting praticly all the wires that were runing to the engine from the wire harness... I know I shouldn't... I'll want to ask you, from were does the ecu take the values for the fuel consumption.. from TPS? MAFS? RPM? That way I might run the necessary new wires onto the required sensor.
    Thanks!!!!

    Fabio G.
    - Looking for a S2
    - Lancia Dedra HF turbo i.e. (4sale)
    - Typ89 Coupè quattro, 20Vt AAN, VEMS, K24-7000@1.3bar (scrapped )

    sigpic
  • mcandmar
    S2Forum Zealot
    • Apr 2004
    • 5118
    • Country: Ireland

    #2
    See here http://www.s2forum.com/forum/showthr...light=computer its the small yellow plug you need to trace, fairly sure it takes a reading from the maf sensor but may be wired into the stock ECU.
    91CQ20v - Gone to a new home
    93UR-S4 - The Magic Carpet
    94S2Bus - The Emerald Express

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    • Nuvo
      S2Forum Possessed
      • Nov 2003
      • 3826

      #3
      Originally posted by 20vQC
      . I'll want to ask you, from were does the ecu take the values for the fuel consumption.. from TPS? MAFS? RPM? That way I might run the necessary new wires onto the required sensor.
      Pin 31 is the fuel consumption signal which is wired to the OBC on the ABY Motronic. I don't have pinout for the AAN to hand. Its probably the same, but I can't confirm this for now.

      Hmm it looks to be pin 32 as per this reference.

      Comment

      • 20vQC
        S2Forum Maniac
        • Aug 2007
        • 684
        • Current: Italy

        #4
        Ok, yes is pin32 on the ECU as nuvo said...but I already have the cluster with the OBC, that is cool now! but MCANDMAR... you think is from the mafs??? Shoot...I'll have to wire it. And wouldn't it decrease the air flow to the turbocharger? K24-7000
        - Looking for a S2
        - Lancia Dedra HF turbo i.e. (4sale)
        - Typ89 Coupè quattro, 20Vt AAN, VEMS, K24-7000@1.3bar (scrapped )

        sigpic

        Comment

        • Nuvo
          S2Forum Possessed
          • Nov 2003
          • 3826

          #5
          Sorry Fabio, I misread your post.

          Comment

          • 20vQC
            S2Forum Maniac
            • Aug 2007
            • 684
            • Current: Italy

            #6
            no worries mate! I'm thinking like 200times about run the mafs wires again, and then put the mafs with the fear of decreasing the air flow for the turbo.
            - Looking for a S2
            - Lancia Dedra HF turbo i.e. (4sale)
            - Typ89 Coupè quattro, 20Vt AAN, VEMS, K24-7000@1.3bar (scrapped )

            sigpic

            Comment

            • S2central.net
              Retired OG Mod
              • Jul 2003
              • 16590
              • Country: Northern Ireland

              #7
              Need to be careful with this one... ECU is the only thing that knows how much fuel is being used - it knows the injector opening times. The fuel consumption signal from ECU to the OBC is the only means it communicates that info - on some proprietry signal format that the OBC understands - I expect its related to duty cycle on that signal but I dunno - never probed it.

              I do remember noting that the RS2 has a different OBC than the S2 for no reason that I clearly understand yet - dunno if its due to the bigger injectors on the RS2 and Porsche never bothering to change the fuel usage signal to the OBC - or whether its due to (maybe) bigger rolling radius on the RS2 wheels that meant the RS2 OBC needed to be tweaked.

              Dunno - would be nice to find out eh !
              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

              • 20vQC
                S2Forum Maniac
                • Aug 2007
                • 684
                • Current: Italy

                #8
                Originally posted by S2central.net
                Need to be careful with this one... ECU is the only thing that knows how much fuel is being used - it knows the injector opening times. The fuel consumption signal from ECU to the OBC is the only means it communicates that info - on some proprietry signal format that the OBC understands - I expect its related to duty cycle on that signal but I dunno - never probed it.

                I do remember noting that the RS2 has a different OBC than the S2 for no reason that I clearly understand yet - dunno if its due to the bigger injectors on the RS2 and Porsche never bothering to change the fuel usage signal to the OBC - or whether its due to (maybe) bigger rolling radius on the RS2 wheels that meant the RS2 OBC needed to be tweaked.

                Dunno - would be nice to find out eh !

                ... or due to the MAFS? the more air is passing through it, more fuel is needed, the ecu makes the calcs and sends it to the OBC. Dunno if the S2 and the RS2 uses the same MAF, but just for the reason that the RS2 has a bigger turbocharger, the mafs will read more air breathed by the engine, so the ecu makes all the calcs to that way inject more fuel... the stock S2 injectors runs out of efficiency at about 300bhp, the RS2 produces 315 and needs a bigger injector that could work good with no big effort at that kind of power and get the right fuel/air ratio onto the engine. I think the MAFS has the fault! hehe and maybe is the MAFS the sensor that will give the propper values to the ecu, and from the ecu to the OBC.

                I have arrived to the conclusion in this moment and tooks me about 15min to have an idea of this (maybe a wrong one).

                Was better to install a fuel flow meter in the fuel lines and get the litres/gallons per minute/hour!!!!! Volume/time equation
                - Looking for a S2
                - Lancia Dedra HF turbo i.e. (4sale)
                - Typ89 Coupè quattro, 20Vt AAN, VEMS, K24-7000@1.3bar (scrapped )

                sigpic

                Comment

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