In 1998 I bought a Triumph Herald 13/60, here you can read about it's restoration and share in a few photo's from it's travels. Please feel free to leave comments to any of the posts, of even email me if you want to.

Monday, February 13, 2017

Converting a Triumph Herald to EFI (Part 1 - Parts and Wiring)

After converting the ignition to Megajolt a few years back, it wasn't long after that I started thinking that Fuel Injection would be the next big project to undertake. After a couple of false starts over the next couple of years, in 2016 I decided that I just needed to get on and do it. Like all projects, there's more than one way to go about it, mainly what ECU to use and whether it will be single point injection, multi-point injection with a single throttle body or individual throttle bodies.

My decision was largely based on cost, so the ECU I chose was a Microsquirt, part of the Megasquirt family, but nothing to do with Megajolt which I'd previously been using, despite the similarity in name. I'd also be fabricating my own inlet manifold and utilising a single throttle body, similar set-up to many cars of today.

So first of all I started buying the bits I needed, I made a shopping list and started collecting the parts. Now the list of bits you need is quite considerable, some you can pick-up cheaply others you may as well buy new.

The major components are:
  • Microsquirt ECU (with extended wiring loom)
  • Injectors (From a Rover 25)
  • Throttle Body (Again a Rover 25 was the donor)
  • Throttle Position Sensor
  • High Pressure Fuel Pump
  • Fuel Pressure Regulator 
  • Fuel Rail
  • Injector Bungs
  • Temperature Sensors (Air & Water)
  • MAP Sensor
  • Wideband 02 Sensor & Controller
  • Various bits of steel to make inlet manifold
  • Idle Air Control Valve (From a Vauxhall)
  • 8mm Fuel Pipe & Hose
  • Various other clips, tubes, connectors etc.
I was at a bit of an advantage as I had the ignition part of this conversion already done. Megajolt and Microsquirt can use the same set-up, which is a trigger wheel on the crank, crank position sensor, Ford EDIS unit and Ford Coil Pack. I'm not going to go into this, but if you want to read more just use the tag on the right called 'Megajolt' and you can see how that is done.

So the first major part was to get as much of the wiring done as possible, then swap ECU's from Megajolt to Microsquirt and run the car using just the ignition side first. This means that when I got to the fueling side, any failure to start I would know that I could eliminate the spark as I knew it to be working OK.

Just to give you a little taster on what wiring is involved, below is the ECU, Loom and Wiring Diagram. Looks a little more daunting than it is, but as long as you're methodical and can follow a wiring diagram it's relatively straight forward.

Microsquirt ECU and Loom
Microsquirt Wiring Diagram
Here is the fusebox and relays that were added.

Relays & Fuesbox
The loom has a total of 35 wires, not all were used, but the majority were. I chose to buy the extended length loom as I wanted to run cables direct to their component without joining, but even this I went through a whole load of solder and heatshrink. All the cables that were needed later for the various sensors and injectors were all coiled up and secured on the bulkhead.

This is the underneath the glovebox, looks more messy in the photo than it does in the flesh and it has been tidied up since. You can just about make out the fusebox and relays along the top, the Microsquirt ECU is in the centre and the MAP sensor just above and right of the ECU.

Underdash cable explosion!
Once I was happy that all the wiring was in place, it was time to power up the ECU and ensure I could connect to the tuning software (Tunerstudio), which it did after creating a new project. I already had a timing map on the Megajolt that worked OK, so it was just a matter of converting from the 10 x 10 Megajolt Table to the 12 x 12 Microsquirt one.

Spark Advance Table
Then the final bit of wiring before trying to start the car, was to move the connections from the Ford EDIS unit to the new ECU. Once done, the car started straight away.

Below is a video of the first start up on ignition only.

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