325e m20 swap; help please

[beckr19]

Hey yall,

I have been searching the internet and nearly every BMW forum page for answers regarding the rewiring for an m20 swap into a 325e. I have a 1984 chassis and a '89 325i motor. I am using the harness from the i, and everything else. I have been trying to adapt the c104 plug to the new c101 connector so the wiring harness works. However, I received the chassis without the c104 plug, so I don't have the original pinouts from a c104 connector. E30 zone wiki has been a major help, however it looks like the colors don't entirely match up, and I am a complete noob at this. 😂
Does anyone know what I need to do to the wiring around the new c101 plug and the wire mess from the c104 plug so I can get most of my sensors functioning? I did read something that said I have to route wires from the ecu back to the plug, but I was under the impression that is only needing if you are running an older wiring loom.
Thanks yall, I appreciate the help.

Here is what I have done now, I believe the connections are correct, but I also have no clue soo...
A

[e30sh]

C104 is Tac and MPG gauge. You can tap the harness wires a few inches from the DME connecor vs. running them all the way out to C101 like a late model. There is an early model guide out there. If not here, check e30tech archives.

Edir. This should help. http://e30techarchive.com/showthread.php&t=28921.htm

[ForcedFirebird]

The m20 needs very few wires to actually run:

Black/yellow is starter engage (needs 12v+ to turn starter)
Blue is alternator charge (needs 12v through dash light)
Green is ignition coil (needs 12v+)
Green/purple is fuel pump (12v+)
Green/yellow (or white) is o2 relay (12v+)

For sensor signals:

Brown/red (or white) coolant temp for cluster
brown/green is oil pressure light
white/green is SI reset
brown/black is check engine light (your chassis won't have)

Since you have early model, your oil level sender might be a 2 pol, but:

Blue/white is oil level
White/blue is oil level

Your chassis will be missing the ground stud on the strut tower for the engine harness ground, but there's a 6mm threaded hole on the battery tray (takes 10mm hex screw) that works great, just be sure to remove paint for good connection. Also, make sure you don't mix up the grounds and the two 12v+ wires in that area. They are all wrapped in black, but you can expose the colors if you peel it back near the eyelet.

[beckr19]

The m20 needs very few wires to actually run:

Black/yellow is starter engage (needs 12v+ to turn starter)
Blue is alternator charge (needs 12v through dash light)
Green is ignition coil (needs 12v+)
Green/purple is fuel pump (12v+)
Green/yellow (or white) is o2 relay (12v+)

For sensor signals:

Brown/red (or white) coolant temp for cluster
brown/green is oil pressure light
white/green is SI reset
brown/black is check engine light (your chassis won't have)

Since you have early model, your oil level sender might be a 2 pol, but:

Blue/white is oil level
White/blue is oil level

Your chassis will be missing the ground stud on the strut tower for the engine harness ground, but there's a 6mm threaded hole on the battery tray (takes 10mm hex screw) that works great, just be sure to remove paint for good connection. Also, make sure you don't mix up the grounds and the two 12v+ wires in that area. They are all wrapped in black, but you can expose the colors if you peel it back near the eyelet.

What do you mean the two grounds? currently I have two ground wires by the coil and the o2 sensor that are on top of each other and on the battery tray ground. Will that work?

[ForcedFirebird]

Two power, one ground. They are all black coated wires, so they are easy to mix up. There should be a set of wires from the fuse box, one eyelet on an 8mm hex screw and one on a 10mm that go to the battery junction block, then the ground lead that typically goes to the strut tower on an "i" model.