MEMS1.9 to MEMS3 conversion wiring.

A copy of the ECU wiring for MEMS1.9 and MEMS3 cars with a pinout diagram for the MEMS3 ECU plugs with my pencil notes on colours to help you in your conversion.
If you are not fitting a MEMS3 engine into your car you will need to swap the following MEMS3 items to the existing MEMS1.9 engine:
Alternator, cam cover and twin coil packs, inlet manifold and plenum with sensors, probably the crank sensor too, since later ones have a different part number, coolant temperature sensor, engine wiring loom, ECU and 5as set with keyfobs, engine relay pack is not a necessity but it saves some faff, although it is not a straight forward plug in I don't believe. O2 sensor, or cut off and swap the plug... MIL eliminator kit if you plan to add a MIL light in somewhere, but the light is not a necessity. The ZnF remap switches the second O2 sensor not present error off anyway. Its worthwile swapping out the exhaust manifold and flexi section for a six bolt version too. You will need to upgrade the permenant live feed to the ECU as the old MEMS1.9 permenant feed isn't up to the job since the MEMS3 ECU powers the O2 sensor heaters, whereas the old 1.9 version uses the engine bay relay pack. (Took me three days to figure that out)
Ignore the rough road sensor, it is not needed. If you fit a coolant level sensor, use the old cat overheat feed from the ECU plug to light up the light on the dashboard... OEM looking.





MEMS1.9







MEMS3







Hopefully this will help.

i take it the engine would still run if i didnt change alternator straight away?

No idea. There is another charge sensor wire that connects onto it. Whether it will strt and run off the battery or throw a sulk i cant say.
Problem arises if it doesnt run.. is it the alternator or something else.

Just thought i would give a quick update.

Manged to get the small plug loom for free! We love MGF's had one lying around chopped up.

I have identified al the wiring colours and it appears all wire colours carry over.

Engine coolant temp sensor is different i need a black one. MEK 000030 is what i need Sorted!
Alternator is different 2 pin connector on 2001 + f'S....... £26 from we love MGF's.
Lambda sensor is different plug......... I could cut plug off old loom?? (not sure on this yet).
Extra lambda sensor..................... Wouldnt be to much of a hassle to fit an extra sensor hole in my exhaust or fit a MIL eliminator. Might get the ECU programmed bypassing it and immobilisor??

Just need to check oil pressure sensor (looks same plug) and Crank sensor.

And should i get the ecu remapped first or after?

Get a new lambda sensor of the correct type. I'm not sure if the voltages it flips between are different on MEMS 1.9 (or 2J) and MEMS3. Oil pressure switch and crank sensor should be the same.

Get the remap done after everything is back together and working. Its much better knowing all of the kit you have is working fine as a standard setup, then remapping than putting a remapped ecu on and something not working (worst case is you have a faulty ecu that you spent money having remapped) It also will eliminate the need for the second lambda sensor (it's automatically part of the remap)

Trouble with that is i have to buy either another sensor or a mil eliminator kit.
I presume the remap would show up any faults with ECU?

It'll run without a second sensor, just show the engine management warning light.

I would personally just prefer to have everything known good before the remap.

Just thought i would give an update,

Replaced the plastic inlet manifold on weekend (what a job to remove)!! I have now fitted a 135 alloy inlet. (what a pain to tighten the lower nuts)!

Rocker cover replaced with coil packs.
Engine coolant sensor replaced from brown to black.
Dizzy and coil removed.

Alternator just delivered.
Mil kit just delivered.

Watch this space!

Well bit the bullet today, spliced in the new loom.

Turned the key...................
Engine revved to 3000rpm cut out...

Realised i hadnt changed the immobilsor.

Running like a dream, sounds smoother at idle. Havent road tested yet as i have a couple of iggles which i will post on a new thread.

Thanks for help guys!!!

hi i am wanting to do this conversion but can't make out the diagrams is it just me lol is there a step by step guide for this cheers :help:

Hi I'm very new here, at the moment I'm converting my 69 mini to rover k series out of a mf tf 160 the breakers that I got my engine from gave me about 12" of loom for me to connect into. After seeing you conversion I have printed it off but is it possible for a step by guide as to how you have done it, your copies have been cut off at the sides and it is a little bit hard to see what you have written at the side of some of them.
I have a full mems 1.9 (2j) loom that I would like to connect the mems 3 engine and partial loom that was supplied with the engine that I have, I have the 5as and a fob, the 5as has 2 plugs ? a grey 1 and a black 1 with about 6" of wire out the back of them whereas the 1.9 loom only has the 1 grey plug. Any help on joining the 2 looms will be greatly appreciated.

cheers Keith.

bump.