Non start M20B25 after swap.

[BillyBoy1990]

hi im new to here, ive heard its the place to be so ive just put a m20b25 (from a pre facelift) into my 318 more door (facelift 1990) and i have no spark! ive checked throught everything including coil relays etc, and now its killing me softly. any suggestions would be much appreciated, thanks in advance, also, would i benefit from putting a 173 ecu in rather than the green label trhat came with the engine? cheers!

[Brianmoooore]

Connect a 12 volt bulb between the coil + terminal and the car's chassis (battery negative connection on the suspension strut top), switch on the ignition and check that it lights. Crank the engine and check that it remains lit, albeit with a bit of flickering.
Pre facelift 325 will benefit from the 173 ECU and wiring loom. This will give you the benefits of the earlier higher compression ratio and the later more advanced engine management.

The forum you have posted in is more for modifications to M20 engines than straight forward M20 faults, so I'll move this to E30 Tech Help, for more exposure.

[Grrrmachine]

If you have no spark, it's also critical that you check the fuel pump also runs when cranking, as one sensor (the CPS) can knock out both.

Brian's advice is a great place to start. For further steps, follow the troubleshooting guide:

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

[BillyBoy1990]

Thanks guys, although I solved it the same day, here it goes...if using a pre facelift motor, box, loom On a facelift, there's a green wire next to the ecu, which needs a live putting to it, once I done that, walla!! It's a wire for the main relay apparently! I've just put a switch on it and will use it for a secret immobilisera˜a Thanks for the replies, I'll swap to 173 this evening. My clocks light up but no action, nothing from the rev counter either, any suggestions on that one? Thanks again

[Grrrmachine]

Brian's bulb-on-coil test was to confirm whether the green wire had power. If yours doesnt, you've either got an immobiliser/obc fitted, or you've got the C101 plug wired up wrong.