5/88 m20 into a 4/87 chassis

[badvibrations]

Swapping my motor into a nicer chassis. I am transferring motor, transmission, wiring harness, and ecu from 5/88 e30 to to 4/87. Does any one know of any compatibility issues I may run into.

[badvibrations]

Can I assume there are no known issues?

[mikeedler]

some harnesses are different. If it was me, I would keep your old harness on the new engine. other than that, it is all compatible.
90% of the time, I had luck with using a dif harness, but there were the 10% when it wouldnt run, and I had to change the harness in the car- still not that hard, but easier when they are both on the ground.

[badvibrations]

Thanks brother...all I needed was some wise words to ease my doubts...now its all excitement.

[kenika65]

I think this fuel tank is bigger in the 88 maby not hum

[badvibrations]

A Concern

Ran into a small problem...
where the wiring harness plugs into the ECU there are some other connectors that split off and run into the dash. The one in the 5/88(the donor car) has 2 wires that run into the dash. The one in the 4/87(the recipient car) has 5 wires that run into the dash. Not sure what to do.

[oldcarskickass]

Ran into a small problem...
where the wiring harness plugs into the ECU there are some other connectors that split off and run into the dash. The one in the 5/88(the donor car) has 2 wires that run into the dash. The one in the 4/87(the recipient car) has 5 wires that run into the dash. Not sure what to do.

Having the same problem here!
4/87 my car and the swap came from 88+ car.

I cannot make my econometer (it always points above 30 litres/100km, and therefore the obc readings are wrong) to work, all other instruments work fine though.
and the ECU always pops out the following error code,
24),it has to do with the speed sensor
I do not know the exact translation from greek to english but the above sums it up.

Sorry if i jacked your thread.

[rs4pro3]

the 87 harness has the c104 plug, these provided power to the ecu from the OBC fuel cut relay, the tach signal to the tach, and the fuel rate output to the OBC. On the 88 harness these functions are run threw the c101 round engine plug. So you either need to run wires from the round plug to the rectangular plug, or just use the 87 harness

[badvibrations]

the 87 harness has the c104 plug, these provided power to the ecu from the OBC fuel cut relay, the tach signal to the tach, and the fuel rate output to the OBC. On the 88 harness these functions are run threw the c101 round engine plug. So you either need to run wires from the round plug to the rectangular plug, or just use the 87 harness

Round plug to rectangular plug? More specifically, which wires to which wires? Or if using the 87 harness are all things gonna match up under the hood and with the 87 harness would i use the 87 ecu or the 88 ecu?

[rs4pro3]

Ok on the big round c101 plug(main plug that connects the engine harness to the fuse box). You want to connect pin 7(green wire) to the green wire on pin #2 of the white 3-pin rectangular plug.
Pin 8 White/black to pin 3 white/yellow wire
and pin 9 black to pin 1 black.
Yes everything will plug in with the 87 harness, and you can use either ecu.

[badvibrations]

Ya. Think I am just gonna use the 87 harness and ECU. Thanks. I may pm you if i have any more questions...

[MR 325]

The cooling systems are different too. You'll either need to put the early style water pump on your motor or convert your car to the late model system.

[badvibrations]

The cooling systems are different too. You'll either need to put the early style water pump on your motor or convert your car to the late model system.

Yes I forgot to mention in my first post that i am also swapping over the whole cooling system too...gotta make mounts on the wheel well to hold the reservoir.

[badvibrations]

Ok on the big round c101 plug(main plug that connects the engine harness to the fuse box). You want to connect pin 7(green wire) to the green wire on pin #2 of the white 3-pin rectangular plug.
Pin 8 White/black to pin 3 white/yellow wire
and pin 9 black to pin 1 black.

If I were to do this should I just splice into the lines(green, white/black, and black) still allowing them to continue in to the ECU? Or cut them and prevent them from continuing to the ECU?

[badvibrations]

anyone?