M50 Loom and ecu

[HairyScreech]

This is kind of m50/52 but also m20 related so bear with me.

looking to convert to the motronic3.1 in preparation for the 2.8 so looking for a complete loom ecu and sensors.

Have tried ebay but the cheapest route that way seems to be a complete engine and loom, strip the loom and sensors and punt the bare engine on.

Anyone on here got what i need?

what should i be paying and what should i be looking out for.

i'm working on the theory that it will be the same electrical mods needed as the 24v swap and then the engine adapted to take the various extra sensors.
Cant be too hard right?
right?

[DanThe]

Famous last words
It has been done before, to a B20 though..

If you want the ECU to mount under the dash in the original place you will need an E36 loom, if you use the E34 you will have to extend every wire to get the ECU into place.

You will need none vanos stuff which is getting thin on the ground now

[HairyScreech]

any actual reason not to use single vanos stuff with a chip switch?
after all its just a cam dephaser and people do lock it out.

are the maps significantly different for the two set ups?
is it possible to use a non vanos ecu with a vanos loom and sensors?

[DanThe]

Actually I think you can use the vanos loom, im sure eko on here did that with one of his engines

[HairyScreech]

After a bit of looking it seems the guys that did it a while back used the 403 ecu which has the same crank position sensor position as the m20.
Downside of that is the non upgradable hot wire maf and no knock sensors.

Which i think means i am best looking at the red label 413 ecu, this will give me the benefit of knock sensors and a hot film maf for when i go b28.
There are however a few issues that need to be overcome:

1. VANOS - I am led to believe this will run fine with the vanos unplugged and will simply behave as though the vanos is not present.

2. The crank sensor - The crank sensor is in a different location on the m50, its where the water pump is on the m20, bit of a pig but i can use a trigger wheel tacked onto the front pully for now, hardly the end of the world. The sensor seems to be a vr.

3.Cam sensor is hall effect, this shouldn't be a problem as the ecu will be wired for it anyway.

4. evap canister - can this just be left unplugged?

beyond those issues it looks like the coolant level and oil level sensors don't change, the brown sensor is maintained and the icv is the same.
The dme set up from the e30 should be fine.

Sensors that need to be changed or added are:
Tps - needs to be a variable from any later engine
Blue temp sensor - change to m50 sensor
m50 air temp sensor
E36 lambda + relay
coil packs
hot wire maf and bodge airbox.
2x knock sensors

now looking at the loom it would seem the best way to go about this is to add to the e30 loom as it is already custom fitted.
i can maintain the loom as is and add an adapter plug and play style for the ecu.
i will need to add:
coil pack loom
air temp sensor wiring
1x lambda wiring
cam sensor wiring
knock sensor wiring

All of these adaptions could probably be added to 1 offshoot and run along a modded injector loom cover.

The only other thing i may need to add is individual earths for the injectors.

i will doodle a schematic up but the changes needed on the face of it seem quite simple.


Can anyone see a massive flaw in my thinking here?

[DanThe]

Im sure there is lots of info on using the 413 here - http://forum.diyefi.org/index.php

[HairyScreech]

That's a quick and dirty schematic.
Everything in black is the origional e30 stuff and everything in blue is the additions/alterations needed for m3.1 or m3.3.1 (although i forgot the knock sensors they could easily go on either side with an off shoot from the coil loom)

The way i see it is the e30 loom is already custom built to fit, with good quality wrap and custom brackets, and by the look of it there is not much need to mess with it as the m20 will still be in place.

The biggest changes will be firstly the MAF, which should be a simple rewire like the m1.3 conversions kicking about.
Secondly the coil loom that runs down the left hand side of the drawing, i should be able to use this to add the extra sensors i need.

This will hopefully mean only small loom tweaks and one additional bit added on.

[DanThe]

Looks easy

[HairyScreech]

Yes, well looks can be deceiving.

See any obvious howlers?

[steve_k]

@hairyscreech, any updates to this yet??