aftermarket ECU wiring

[Shaheenk]

HI guys

I need some help please

I am wiring an aftermarket ECU into my E30 , reason being I have a turbo and need more control and fuel .

what I have done is cut off the ecu connector from the Motronic unit in a hope to wire my aftermarket ECU into that .

I need to know the following.

My Aftermarket needs 12= Ign , I assume this is pin 27 or 37 on the motronic.

I also need to know.....

1. Which pin Goes to the coil -ve
2. Which pin is Coil +ve
3. Which pin is injector +ve
4. What does pin 36 do and does it need +ve or -ve
5. Does the output to the fuel pump relay need -ve switch or +ve switch

On the input side ,

I need to wire the CPS in , which pin is that .

My aftermarket has +12v which says +ve for injectors. but I cant see motronic having +ve in injectors. or does it get this from a relay or the harness.

[maxfield]

http://www.e30zone.net/e30zonewiki/inde ... CU_Pinouts

[Shaheenk]

yeah been through that , seems I don't need to wire the positive from my ecu to the injectors, but I do need to figure out how to switch the dme relay on...

[gromgsxr]

Yeah you do... you can build a simple transistor circuit to do this with a transistor a resistor and a diode or wire up a second relay to ground the main relay in the engine bay and power everything up. the relay option sucks though as if the battery is a bit low you can lose power to the injectors and icv during cranking and it can be a mare to start the car like that.

transistor connections.
1 The Emitter (2n2222a) connects to ground
2 The Base (2n2222a) connect to pin 27 with a 7.5k ohm resistor
3 The Collector (2n2222a) connects to pin 36
4 The 1n4001 diode connects to pin 18 and 36 with the banded end towards 18

[Shaheenk]

mmmm, ok, I found a tread which talks about getting the DME relay to power on with the key, would this not be a better option, My aftermarket has a number of 12Voutputs and a few switched grounds as well .

[gromgsxr]

the dme relay powers the ecu on pin37 i dont think your after market ecu will be able to provide a ground output to turn on the dme relay, if the does not have power its self.

iv been using the transistor circuit for about 3 years on my ms3 and works great.

[Shaheenk]

you sir are correct, I will build the required transistor circuit to power the main DME relay .

thanks