Thought I'd share how to wire the 122 pin connector to DIYPNP megasquirt since there are currently no instructions, and had to figure it out myself.

On the adapter board the inputs are labeled above as A,B,C,D, and E.

At the top of this page you can see the pinout for reference

http://www.bellengineering.net/templ...CU_diagram.pdf

We will start with the connectors from section E,C, then D excluding injector and spark inputs.

E

IAT(Intake air temperature sensor): 26, 4N
TPS(Throttle position sensor): 17, 4V
O2(Front oxygen sensor): 28, 4W
CLT(Coolant temperature sensor): 15, 4P
12v source: 9, 4AF
VREF(Regulated 5v power): 3, 4L
SG(Sensor ground): 4, 4O
GND(ground): 1, 4A
12V(Backup power, Battery): 21, 4AG

C

Fuel Pump: 5, 2M
IAC: 6, 2P

D

OPTO - (CKP, Crankshaft Position sensor): 16, 3Y
Vr2(CMP, Camshaft position sensor): 15, 3V
GND(ECU ground): 8, 3B
Tach: 21, 3o
GND(Fuel injector ground): 1, 3A


Now for the injector and spark outputs, as well as the pullups needed.

D

IGN1(Ignition one): 18, 3F (Provides spark for cylinder 1 and 3)
IGN2(Ignition two): 19, 3i (Provides spark for cylinder 2 and 4)

C

INJ1(Injector group one): Wire 1 and 3 here
INJ2(Injector group two): Wire 2 and 4 here.

Pullups: Found on bottom right side of board these are needed for CKP, Vr2, and IAC to function.

R3: Install 470 Ohms resistor to 12v
R4: Install 470 Ohms resistor to 5v
R5: Install 1N4001 Diode with banded side to 12v

In the end, make sure three wires are connected to the GND section, two are connected to 12v, and one is connected to SG.

Heres a base tune in case you can't find one.

 

r3 should go to 12v.

 

Changed to 12v, but 5v works fine for my rpm reading. Should the 12v used the 1k resistor.

 

470ohm. 5v it's fine but 12v is what you should use for it.

 

I would expect pullup to either 5V or 12V to work fine here. It's just making a square wave. The opto input is actually triggered by current, not voltage.