M20B20 to M20B20 swap, straightforward right?

[huff3r 347]

Ok, so I am putting a replacement engine in my car. This replacement theoretically speaking is the same as the engine coming out, PFL M20B20.

But i have this plug on my new engine, which i cannot find anywhere in my engine bay!!

And I can't find this plug, attached to the fuse box, on my new engines loom, even though its pretty well integrated into mine!

Anyone got any clues?

There are a few other subtle differences in the wiring loom, wires routed different ways, and grouped with other wires etc, seems very strange to me when they are supposed to be the same

[Jamez 2147483647]

they connect to each other, only problem is the plug types are different

Here is the conversion.

[huff3r 347]

they connect to each other, only problem is the plug types are different

Here is the conversion.

Cheers so much for that, now i have to figure out what to do about it haha.

I didn't realise they changed the wiring half-way through, seems a bit stupid really...

Maybe i should just de-loom my engine, and chuck the old loom on the new engine? To keep it all factory...

[Forrest 35]

^ Cut and connect bro, its not a show car....

[Jamez 2147483647]

Maybe i should just de-loom my engine, and chuck the old loom on the new engine? To keep it all factory...

thats what I did, only the wires to the starter motor and alternator were a different size (cut them to a prong shape instead of a circle)

Also the distributer plug was different but you can swap the female side of the plug out from the other engine.

You might not encounter these problems tho, I was taking out a 1983 M20B20 and swapping to a 1987 M20B20

Edited March 15, 2010 by Jamez

[huff3r 347]

thats what I did, only the wires to the starter motor and alternator were a different size (cut them to a prong shape instead of a circle)

Also the distributer plug was different but you can swap the female side of the plug out from the other engine.

You might not encounter these problems tho, I was taking out a 1983 M20B20 and swapping to a 1987 M20B20

Cheers, i dont know what year my new engine is but i think i'm doing pretty much the opposite haha. As long as it runs and doesnt smoke like a b**** when its warm im very happy

[huff3r 347]

^ Cut and connect bro, its not a show car....

Haha, maybe... shouldnt be too tricky to swap the loom over tho ae? Or if there are any E30s at pick-a-part i could even make a harness for connecting them

[antil33t 90]

It's easy as to swap looms, I had to do that when I did the B25 swap, otherwise the autobox wouldn't work.

just lable EVERYTHING... there's not really a whole hell of alot to change over... at least on the Motronic 1.3 ones there isn't.

[huff3r 347]

It's easy as to swap looms, I had to do that when I did the B25 swap, otherwise the autobox wouldn't work.

just lable EVERYTHING... there's not really a whole hell of alot to change over... at least on the Motronic 1.3 ones there isn't.

Yeah, and fortunately everything seems to use different sized plugs/lugs etc, so not too tricky by the looks of it. However not swapping them over would be easier

[e30ftw 410]

Watch out for the c104 connector.. it's a 3pin plug coming off the engine loom right after the ECU connector. If your new engine has this, or your e30 has this you need to connect it or else the car will not start and you will have no tacho. I did this for a previous swap where I put a pre-FL m20b20 into a facelift m20b20 with the circle plug. Had to change plugs then wire up the c140 which is ECU power, Tacho and fuel consumption IIRC.

[Jono51 59]

hey,

I've got looms , plugs and wiring diagrams. pop in and have a look or a chat about it

cheers

Jon

[huff3r 347]

Watch out for the c104 connector.. it's a 3pin plug coming off the engine loom right after the ECU connector. If your new engine has this, or your e30 has this you need to connect it or else the car will not start and you will have no tacho. I did this for a previous swap where I put a pre-FL m20b20 into a facelift m20b20 with the circle plug. Had to change plugs then wire up the c140 which is ECU power, Tacho and fuel consumption IIRC.

Cheers, both engines had this and i labelled it when i unplugged it. My ECU is mounted 10-15mm lower than standard to fit beside the rollcage so it was very easy to unplug and sort out

I've used the wiring diagram in one of the posts above ^^^^ to build a harness using two connectors from the PFL E30 at pickapart and one of the E34s (wow the E34s have a lot of the pins in use! Like all of them!). Hopefully i got it right