The last puzzle piece falls into place.

The only major part I’m missing from this project is an updated version of Bosch’s engine management. The high-compression M30 motor I’m intending to use in this car uses version 1.0 of Bosch’s Motronic Digital Motor Electronics. In Euro specification (“011” DME), it doesn’t support an oxygen sensor or catalyst. It also cannot store error codes. It has a few other faults: rough idle, lean midrange and difficulty passing our strict emission tests. It’s also difficult to tune.

I’ll be fixing these problems with the somewhat more powerful version 1.3 from the later US-spec M30B35 (“179” DME). Idle control and part-throttle performance are far better. It uses very common high-impedance fuel injectors that can be easily exchanged to (crudely) tune the motor. It also eliminates the painful little cold-start injector that BMW had mounted in the most inaccessible crevice of the intake manifold. The limited OBD-1 is another small advantage. Other improvements are a slightly higher-capacity alternator and a more efficient A/C compressor, in case I need a spare.

Best of both worlds, I say.

The E34 harness ended up needing a lot of work to fit well in the E24. I had to extend the AFM harness, the DME harness is too short, I needed to adapt the C101 canon-style connector to the fuse box, the sensors don’t match, the WBO2 needed to be integrated into the system, etc..