Modified E34 525 engine into E30 323i

[NauticAl]

Hi All
I am mechanically close to completing the rebuild of my 1984 E30 323i with a stroked 2.9 litre M20 2.5 engine from a 1989 E34 525.
The whole project has new mechanicals from end to end. The only original drive parts are the 5 speed manual trans and the propshaft.
Actually, probably the only original car parts are the body panels, the fuel tank, the front and rear subframes, the lower parts of the front struts and the transmission bits.
The new 2.9 litre engine has a fully re-built US sourced Bimmerheads "race" cylinder head and stroker kit, Fritzbits exhaust and a megasquirt PNP2 ECU.
The problems I am having are marrying up the original wiring from the LJetronic 323 with the Motronic 1.3 from the auto trans E34.
As the car is being re-built as a (Tasmanian) road legal tarmac rally car, I am removing or ignoring the Active Check Control sensors and wiring - the check control panel was in the way of the demountable front roll cage hoop and it had to go.
Also, the MSPNP2 ECU has very simple requirements for engine management - just an air temp sensor to replace the stock AFM and a wideband 02 sensor and controller.
What has me confused is the E34 engine loom. I only got the engine and the engine wiring loom (with no ECU) so I don't have the whole E34 to study and I am having to work things out from first principles by trying to reconcile wiring diagrams from the two models.
I have welded up a sealed alloy box to locate the Megasquirt ECU on the end of the E34 loom in the RHS of engine bay (where the E30 battery used to be), as this is where the E34 ECU used to live.
The E34 loom has 3 relays on the loom near the 55 pin ECU plug - an 02 relay, a "main relay" and a fuel pump relay. I won't need the O2 relay, as I bought a new wideband sensor and board with the MSPNP unit, but I don't know about the other two.
The original 323 loom doesn't have these - the relays are all on the fuse box.
I am trying to understand this. If I just make cross-connections between the C101 plugs on the looms (one is rectangular, one it the new round one), will the system work, or do I need to make some connections/disconnections with the relays?
Has anyone already sorted this issue out?
One other problem I have come up against is that the 323i was a Europe (and Australia) only car, so a lot of the US literature does not mention it and I suspect that with mine being a very early model, mine may not conform to the common specs.
As an example, the books say that all 6 cylinder E30's had medium case diffs. Mine had a small case diff, which meant I had to buy a whole new LSD and shorter drive shafts.
Cheers
Alan - Tasmania Australia

[flybynite]

Welcome!

Having a 323i myself I can say the jetronic is fine confined to a museum and mine will also be going Motronic 1.3 when it goes back on the road.

Have a look at this:

https://www.e30zone.net/e30wiki/index.p ... tronic_1.3

Particularly the bit "From Jetronic" The links there to the C101 plug layouts will help.

Mine had a 168 small case too (which is not going to stay) be glad yours did not also have the dogleg box because they are made of chocolate and could not take and Alpina-tweaked 323i let alone a fully built 2.9

A used Haynes manual is a useful thing to have (Orange one which confusingly has an E21 on the cover) has a lot of good stuff for the 323i including wiring diagrams. Not sure they had them down under but I'm sure you could get one sent out from ebay?

[NauticAl]

Great - thanks for the info.
I have already looked at the e30zone ECU conversion page but it does not make any mention of the relays and unless I remove either the old 323 set or the E34 set, I am going to wind up with two sets. The relays on the E34 harness depend on the engine harness for their inputs and outputs (there is no other connection to the car electrics) while the 323 set all sit in the fuse box, with connection back to the body harness.
I have an copy of a Haynes manual titled "BMW 3 & 5 Series Manual". There is no cover as such, so not sure about the orange cover.. Is this the one you are referring to?
Cheers
Al

[flybynite]

Great - thanks for the info.
I have already looked at the e30zone ECU conversion page but it does not make any mention of the relays and unless I remove either the old 323 set or the E34 set, I am going to wind up with two sets. The relays on the E34 harness depend on the engine harness for their inputs and outputs (there is no other connection to the car electrics) while the 323 set all sit in the fuse box, with connection back to the body harness.
I have an copy of a Haynes manual titled "BMW 3 & 5 Series Manual". There is no cover as such, so not sure about the orange cover.. Is this the one you are referring to?
Cheers
Al

No the "BMW 3 & 5 Series Manual" is a later one and all-but useless. You need the earlier one just for the E21/E30 preferably the one up to 1985. There is a later one up to '87 with a 325 appendix that might be better for what you are trying to do.

Not had much to do with 5-series M20 wiring so not much help. Zone wiring guru has gone AWOL for a while

These are what I use for the 323

Haynes.jpg

Haynes 2.jpg

[NauticAl]

Great - I have just ordered one from the UK. That will help a lot.
Cheers
Al