Rpm input signal to tacho in 405 XU10J2

Karnadi · Post by **Karnadi** » 14 Jun 2005, 20:23

Hi all,
I'm installing APEXi Super Air Flow Converter (SAFC) piggyback in my 1996 2.0L Pug 405 (XU10J2 with Marelli 8P.20 ECU).
So far I've found the correct connection to : MAP signal, TPS, Power, Ground.
But I still haven't found the correct rpm signal input.
These are what I've done to get the rpm signal :
1.) In a non-Injection car, usually tachometer gets its signal directly from ignition coil, so there's where I start.
I tried to tap the ECU 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 rev 2000rpm, the signal read by SAFC were somehow "jump" at certain interval to around 3500-4000 (I was sure that the actual engine speed is constant, with slight variation 50-100rpm).
So tapping from ignition coil doesn't work.
2.) I tried to tap the ECU wiring to Crank sensor :
ECU pin 11 (Crank sensor pin 1).
First start, it was fine, but after a few minutes, at idle rev 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.
3.) 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 a correct & reliable rpm signal to feed my SAFC.
I'm thinking to tap the input signal to the tachometer.
Does anyone know which wires I should tap ? (which ECU pin ?)
Thanks in advance.
Regards,
Kenneth

PowerLee · Post by **PowerLee** » 14 Jun 2005, 20:33

Hi
Pin no 5 on the ECU is the rev counter feed on this system

Karnadi · Post by **Karnadi** » 16 Jun 2005, 04:48

Thanks PowerLee.
I'll try to swap the cable this Friday [:D]

Karnadi · Post by **Karnadi** » 18 Jun 2005, 17:04

Power Lee,
Thx man, u're awesome [:D].
RPM reading was OK now.
I'm going to CO test the car, re-adjust the CO level, then map the fuel.
One more thing, the SAFC has a knock sensor input.
Do you know which ECU pin that connects to the knock sensor input ?
Thanks in advance.
Regards,

PowerLee · Post by **PowerLee** » 18 Jun 2005, 18:13

Hi
The knock sensor is connected to pin number 33
There is also a connection for the shielding of the sensor to pin number 34.
Pin 16 seems to be an earth connection.