RPM Signal for tapping piggyback in 405 XU10J2
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  1. #1
    Join Date
    Aug 2004
    Jakarta, Indonesia

    Icon9 RPM Signal for tapping piggyback in 405 XU10J2

    Hi all,
    I'm installing Air Flow Converter piggyback in my 1996 2.0L 405 (XU10J2 with Marelli 8P.20 ECU).
    So far I've found the correct connection to : MAP signal, TPS, Power, Ground.
    But I still can't get the correct rpm signal input.
    I tried to tap the wiring to Ignition Coil : ECU Pin 1 (Ign coil 1 to cyl 1-4) and ECU Pin 19 (Ign coil 2 to cyl 2-3), but the rpm signal catched by the SAFC was erratic.
    At constant 2000rpm, the signal read were somehow "jump" at certain interval to around 3500-4000 (I was sure that the actual engine speed is constant).
    I tried to tap the wiring to Crank sensor : ECU pin 11 (Crank sensor pin 1).
    First start, it was fine, after a few minutes, at idle the signal read by SAFC is 10000 rpm.
    Step on the accel at 5% TPS 1750rpm, signal read is OK = 1750rpm, but at higher rev the reading become erratic again.
    Final attemp, I tapped ECU pin 28 (Crank sensor pin 2).
    Idle reading was fine = 850-1000rpm, 1000-1800rpm was also fine.
    Incorrect reading begin at 1800-2800rpm (shown at 6000-7000rpm).
    Step on more further, 2800-4000rpm reading was also fine (correct reading).
    More than 4000rpm, the rpm reading became incorrect again.
    I haven't tried 5000-6500.
    My problem is : I need to tap the correct rpm signal to feed my piggy, I'm thinking to tap the input signal to the tachometer.
    Does anyone know which wire to tap ? (which ECU pin ?)
    Thanks in advance.


    '96 P405 STi
    K&N, Ecotek, Custom Pulley

  2. #2
    Member senthil16V's Avatar
    Join Date
    Mar 2004


    tap from the throttle position sensor/throttle potentiometer...its a yellow sensor located near the throttle body...hope this helps...

    With Rgds,


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