C101 M10 -> M20

[Robert45IAN]

Im having an issue with starting my car after upgrading to the M20B25. Symptoms include fuel injectors staying open and filling the head and ecu getting hot. (ecu was running fine before swap).

For some reason the c101 in my 318i was already a circle and not a rectangle like everyone else had so the pins just has to be match. My mechanic has tried his best to match them all up. Has anyone got a list of what matches what so i can double check. Here are some photos.

This is what my m10 c101 looked like. it was supposed to be a rectangle but it wasnt.



This is the c101 from the m20 side.


And the engine

[Grrrmachine]

The Wiki is built for stuff like this:

http://www.e30zone.net/e30zonewiki/index.php/C101

READ THE WARNING!

[Robert45IAN]

Ive actually got a copy of that printed out at the mechanic. It was my first point of reference when it came to the c101

[Grrrmachine]

So go through the table and pair up the wires according to function (not colour).

For your problems though, I don't think the C101 is the issue. Nothing to do with the injectors goes through the C101 - it really only provides info for the instrument cluster, signals from the ignition switch and a signal to the fuel pump relay. I don't see how any of that could cause your injectors to stick open.

[gooner1]

Hi Robert,

when you have solved your problem, any chance of a write up
of the complete conversion, with as many pics as possible.

Have the same car myself, 87 M10 1.8i auto, and while i'm
more than happy with the way it drives atm, the future may be different.
Cheers, Rob.

[Grrrmachine]

You know there's an engine swap write-up, right?

http://www.e30zone.net/e30zonewiki/inde ... Swap_-_M20

[Robert45IAN]

The mechanic doesnt think the c101 is the issue either. everything has been wired up accordingly and triple checked. The mechanic feels the issue is the ecu so im hopefully checking my ecu in another persons 325i tomorrow.

Note that after my car had the engine in and wired up i didnt have a radiator and oil cooler (donor car was a front end damaged but ran fine) so the mechanic turned it on 4-5 times quickly without the two and it ran but didnt check for throttle response.

Overnight i received the radiator and oil cooler and the next morning it was fitted. The car didnt start, the battery was died overnight, so the battery was charged up and the car is where it is now. No spark and funky fuel injectors. The mechanic checked to see if anything was draining the battery but nothing. The injectors are getting a constant earth that stops when the ecu is removed. the ecu is also not throwing a signal for the spark. I dont understand how overnight the ecu was damaged by a dead battery

[Robert45IAN]

The engine swap page was exactly what i was trying to find a few weeks ago and try giving the engine swap a go myself. Would have saved me money and now time. Maybe next time around.

[Brianmoooore]

Plenty of M10 engine looms had the twenty pin round C101 connector in E30s. Rectangular plug was only used in the first part of M10 production, and any engine swap of an E30 engine into an E30 shell where both halves of the C!01 are 20 pin should be plug and play, apart from ABS supply wiring as detailed in the 'wiring warning' in the wiki.
Haven't got time at the moment to read though this properly, but check that the medium sized brown or brown/orange and red wires (both in black outer sheaths) are connected the right way around at the battery.