The basics: MegaSquirt II extra (
http://www.msextra.com/ms2extra/). Another good site for the hardware is
http://www.diyautotune.com/
If you spend some time working through the applicable portions of this site and other MS sites it should come together. I recall somewhere seeing someone adapt the D-Jet ECU box/wiring harness (I have no idea now, but it involved gutting the ECU and adding the new board).
I started from a CS configuration, which meant building a new wiring harness – not a big deal. Most of my parts were scavenged from a 735i (1991)
Fuel – Added new fuel supply line from the tank and used the old line for the return. Then added an in-tank pre-pump (16 14 1 179 415) with a sending unit (16 14 1 152 266) and main pump (16 14 1 179 232). I Installed an adjustable pressure regulator near the custom built aluminum clamp-on fuel rail (no more short hoses to each injector). The existing fuel rail can probably be used.
Ignition – I used the 60-2 tooth wheel (at front of engine) & VR sensor (all straight bolt on). You will need to fix the distributor so is does not advance via mechanical or vacuum means. I finally got rid of it and am using a Bosch 3-coil wasted spark pack, again, with some mods the ECU.
Coolant sensor – The CS coolant housing needs an addition coolant sensor for the MS system. You may be able to tap a new port into the housing. I used the newer housing which has room for 3 sensors.
Air temp sensor – I tapped this into the right side of the air intake plenum.
O2 sensor – I added a wide band sensor to the front exhaust manifold along with the Innovate LC-1 controller. A bung was brazed on the rear of the front manifold. I had to trim a small corner off of the heat shield. In the future I would like to add a second WB O2 sensor to the other manifold.
Air measuring – The MAP sensor is built into the MS ECU. I added a second MAP sensor to compensate for altitude. The great part is that the MAP sensor allows you to use your current D-Jet airbox and bellows to the throttle. This is an elegant solution: you only need to run a vacuum hose from the intake plenum port to the MS ECU box. None of the newer air flow or mass metering is needed.
TPS – MS requires a 0-100% TPS. The CSI version is either open or closed, so will need to be replaced with a newer unit (13 61 1 726 591). You will need to modify the butterfly shaft and build an adaptor plate to fit the existing throttle body. I wanted to maintain the mechanical linkage to the gas pedal. I used a throttle body from a 1976 vintage M30.
Cold start fuel valve - deleted. This can be removed from the side of the plenum. I used this port for connecting to the idle air control valve (Bosch 3-wire type) to the port on the throttle body. The MS system uses the main injectors to added fuel during starting. There are various settings for various temperatures at cold starting and transition to operating temp.
Some of these modifications involve getting into the MS ECU box and soldering, adding wires, etc (scary and fun with a fair amount of support available).
The most difficult part is the tuning. You have a spark advance, VE and AFR table to layout. There are some programs to help with tuning, but you will definitely need to spend some time on the dyno. I got the system running on the 3 liter engine before I tore the car apart for some resto work. , I expect to be incorporating it onto the rebuilt 3.5 l engine and spending more time on the dyno.
The above is a work in progress and I hope to add more descriptions, references, photos in the future, as time and motivation allow.
