So, I’ve now ruled out human error on the inverter control board. I sent it across to a fellow OpenInverter forum member on the wrong side of the Pennines and he dropped it into his working setup. Sure enough, the DC supply voltage was all over the place. He’s kindly trying to work out why now. In the meantime, we’re cracking on.

We’re making progress on three parts of the project: the throttle pedal, the high voltage junction box, and stripping the car.

Throttle Pedal

In this project I’m using a BMW 1 Series electronic throttle pedal to replace the old mechanical unit. The challenge is that – understandably given the ~20 years between the two cars – they have different fittings. So I’ve been working up an adaptor that will allow the 1-Series pedal to drop into the Z3 mount. This is 3D printed from PETG and currently on its third iteration

My 3D printer has chosen this moment to play up, so I can’t print the latest – and what I hope will be the final – iteration straight away. But it’s nearly there and I should have it sorted this weekend.

HV Junction Box

One of the first things I got working with the inverter was the high voltage electronics for the drive system. This is a relay and two contactors (effectively high voltage/high current relays) that pre-charge the capacitors in the inverter then connect it to the full force of the main battery pack, under control from the clever EVBMW control board. The next step is to assemble all this, along with a massive fuse, and maybe some other gubbins, into a weather-proof junction box

I’ve narrowed down my selection of boxes to a variety of ABS units with steel mounting plates in the base. I’ll probably order one this weekend. In the meantime I’ve received the standoffs I need to mount the high voltage connections to. Just need some bus bars now.

Engine Removal

Turns out the M44 engine I have is worth a few quid. If I’m lucky I’ll recoup the entire price of the car, minus delivery. So I’ll be careful getting it out. Ancillaries are first and my workshop now contains some plastic trim and an air box. Radiator and some other bits will come out tomorrow, work permitting – I’ve started to get busy at a financially-welcome but project-blocking time.

Engine crane ordered from eBay (£130) has arrived and will be assembled to lift the lump out this weekend with a little luck. Then it will be on to a pallet and covered with a tarp ready for eBay listing.

Onwards and upwards.