'87 m20 in an '88...

[NeilMFD]

Ok, i know i'm not technically supposed to do this. But I just got an '88 325ix with a bad motor and i would like to swap my '87 325is motor into it. I know there are slight variations with the '88 m20 from the '87 m20, but if i transfer the whole wiring harness along with the motor will it work? I'm talking about the block,wiring harness, alternator, starter, etc. all being swapped over. On my '87 325is there were only two connections connecting the ECU/wiring harness to the rest of the electrical system -
One -

Two -

So do those connectors look the same on an '88 325is/ix?
Thanks!
~Neil

[UNHCLL]

I did the oposite. 88+ motor into my 87.
Wiring harness is identical. No need to swap.
However, you will need to change to the later style water pump. It has different inlets/outlets/etc. than the 87 water pump. If you're doing the pump, do the timing belt and tensioner too.

HTH,
Chris

[nando]

you also have to relocate the oil dipstick. the ix oil pan is not the same so the is location won't work.

[rs4pro3]

on my 88 that second set of 3 wires is run threw the c101(plug in your first picture)

[NeilMFD]

on my 88 that second set of 3 wires is run threw the c101(plug in your first picture)

This is a pic of some wires coming from the ecu in my friends '88 325is - Is this what your talking about?

~Neil

[NeilMFD]

you also have to relocate the oil dipstick. the ix oil pan is not the same so the is location won't work.

I have to swap over the whole oil pan too. Is there anything else i will have to pull off the '88 motor? Is it the same oil pump? I think i will keep the '88 cooling system, i heard it was better. So i'll put an '88+ water pump and such.
Thanks!

[rs4pro3]

This is a pic of some wires coming from the ecu in my friends '88 325is - Is this what your talking about?

~Neil

Ya that is used for just the AC functions on the 88, and the wires are rerouted threw the c101(big round plug in your first pic)

[rs4pro3]

ok here is what you'd need to do, on the 87 325i engine harness where that 3 pin plug is by the ecu(this is called the c104 plug), Pin 1-black wire (engine speed), needs to be connected to pin 9-black wire on the chassis side of the 88's c101 plug. Pin 2-green wire(obc fuel cut), needs to be connected to the + post on the ignition coil. Pin 3-Yellow/white wire needs to be connected to pin 8 on the chassis side of the 88's c101 plug.
that is the only wiring you'd need to do.

[NeilMFD]

ok here is what you'd need to do, on the 87 325i engine harness where that 3 pin plug is by the ecu(this is called the c104 plug), Pin 1-black wire (engine speed), needs to be connected to pin 9-black wire on the chassis side of the 88's c101 plug. Pin 2-green wire(obc fuel cut), needs to be connected to the + post on the ignition coil. Pin 3-Yellow/white wire needs to be connected to pin 8 on the chassis side of the 88's c101 plug.
that is the only wiring you'd need to do.

Awesome, thats what i wanted to hear! I will post again when i get the new motor in and the wiring crap figured out.
Thanks!
~Neil