M10 to M20, what all am i missing?

[EThirty318i]

Long story short, I took my m20 out of my 87' vert, i totaled it bad! only shifter the tranny and motor slightly. while pulling the motor we noticed that the wiring harness is completely shredded. But the interior wiring and ecu wiring is still good. My question is, do i need an intire new harness for it? or would i be fine with my 318's harness and just swap the ecu's?

[Cabriolet]

short answer is no. the m20 is motronic 1.3 and the m10's wiring harness wont even come close to working on the m20b25.

[Jaxx_]

nope. won't be able to use it at all. I would get an entire wire harness to be honest. Better than chasing your tail when you get it running and try to diagnose a no start condition or something stupid like that because of some random wire grounding on the chassis.

[EThirty318i]

alright cool deal, and what if i dont want to run anything extra? like just the motor, guages, lights, stereo?? no ac, heat, etc