M10 to M20 Swap + Wiring Guide

[blackmamba1]

I have searched but anything that I have found is so old that the link has expired.

I am in the process of swapping an 1987 325 is M20 into my 1985 318i.

I know I am going from the square plug to the round plug but I need the pinouts.

[Hick]

haha, im about to do this also!

not sure what the answer is, but im looking aswell.

[e30cbe]

and i'm planning to convert a carb 316 to 325i - and beyond hopefully

[dinkyracer]

and i'm planning to convert a carb 316 to 325i - and beyond hopefully

way to go buddy ...

[Jean]

Any luck ?

[Hick]

I havent started. I was going to find a rectangular c101 plug and round c101plug. Cut the engine side on the rectangular, and chassis side on round to make a jumper. i havent even found a rectangular c101 plug

[new2bmw]

me too???????????

i have a 1984 318i, i am planning on going turbo with. But,,, today I found a 1987 325i with a manual tranny and strong engine and the body is ok. i was thinking of taking the engine and tranny and putting them in my mint body 318i and then part out the rest of the 325i. am i stupid or does this sound like a good idea to anyone else? As of right now i own 2 m10 engines and if i pick up the 325i for $500, that would be one m20 too the list.
Other then swapping out the tranny and engine is there other parts i would need to change on my 318i? would my new H&R's still work alright, and my new Bilstein sports? i dont want to waste the parts i have already bought doing this swap.
HELP PLEASE!!!
Larry

[Cooper]

I converted my 85 e to an 87 i using this diagram (Got it from somebody on this site, thanks again) In my research to do my deal I read about the 318 square c101 being the same as the 85 e so this should be all you need.

I cut the engine side c101 off the 85 e harness and the round c101 off of the 87 i, soldered and shrink tubed them together.

[Hick]

I made my plug, 84 85 325e c101 plug is the same as 84 85 318i c101 plugs. E28s have the same plug, but the pins used are not in the same location, so you could rearranged the pins in an E28 plug, but from what ive heard, and tired, that is a PITA.

Anywho, heres the wire codes

Pin Number - Rectangular C101 -- Round C101 - Pin Number
1 - Blue -- Blue [X2] - 1
2 - Blue/Purple -- Blue/Yellow - 2
4 - Brown/White -- Purple/Brown - 4
6 - Green/Yellow -- Green/Yellow - 6
7 - Green/Purple -- Purple/Red - 13
8 - Black/Yellow -- Black/Yellow[X2] - 18
10 - Green -- Green - 7
15 - Blue/White -- Purple/Green - 10
16 - Brown/Green -- Black/Brown - 5
17 - Blue/White -- Blue/White - 11

*There are TWO Blue/White wires on the Rectangular C101 Plug. The smaller gauge wire is to pin 17.*
**Pin 16 on the Round C101 plug is not used**

[Hick]

It should also be said that i have not tested mine yet. i will be swapping the motor this weekend.

[Hick]

BUMP

Did the swap this past weekend. Wiring worked like a charm. NO issues to speak of other than a stuck injector that needed replaced.

[blackmamba1]

Bump

Worked perfectly!!!

Mods sticky this thread

[vivalegreg]

can you guys post an update on how the cars are running after the swap? any issues you may have come up with then and issues you may have now? don't our cars have thinner struts then 325 cars? does this swap have any issues with that? let those know who have interest in doing this swap and well, me! im in the process of doing it!

[new2bmw]

hey

i know this is an old thread but maybe someone can post their results? i am about to do a m10 to m20 swap and need all the help i can get. would appreciate any info/help.
thanks guys!

[e30cbe]

I converted my 85 e to an 87 i using this diagram (Got it from somebody on this site, thanks again) In my research to do my deal I read about the 318 square c101 being the same as the 85 e so this should be all you need.

I cut the engine side c101 off the 85 e harness and the round c101 off of the 87 i, soldered and shrink tubed them together.

I made my plug, 84 85 325e c101 plug is the same as 84 85 318i c101 plugs. E28s have the same plug, but the pins used are not in the same location, so you could rearranged the pins in an E28 plug, but from what ive heard, and tired, that is a PITA.

Anywho, heres the wire codes

Pin Number - Rectangular C101 -- Round C101 - Pin Number
1 - Blue -- Blue [X2] - 1
2 - Blue/Purple -- Blue/Yellow - 2
4 - Brown/White -- Purple/Brown - 4
6 - Green/Yellow -- Green/Yellow - 6
7 - Green/Purple -- Purple/Red - 13
8 - Black/Yellow -- Black/Yellow[X2] - 18
10 - Green -- Green - 7
15 - Blue/White -- Purple/Green - 10
16 - Brown/Green -- Black/Brown - 5
17 - Blue/White -- Blue/White - 11

*There are TWO Blue/White wires on the Rectangular C101 Plug. The smaller gauge wire is to pin 17.*
**Pin 16 on the Round C101 plug is not used**

Thanks a ton gentlemen, this will be needed to complete my m20b32 build which will hopefully be in soon .:)