Modern ECU for 31 ITS

This thread is to discuss the possibility of swapping the stock fuel injection electronics for a modern ECU. A megasquirt is the leading contender for the replacement.

The SCCA has approved this modification for competition in Improved Touring.

Everyone is welcome to comment

Going to list out some pros and cons here to get the conversation started.

Biggest con is the stock system is absolutely bullet proof. No failures or problems in 47 years of service including use under competition conditions.

Pros:
internal data logging - current specs for MS3Pro is 28 channels @ 100Hz
fuel only mode
compatible with O2 sensor
idle air bleed control
electric fan control
alternator field control / voltage regulator
fuel pump control

There is more but that last one is a big deal. This car already experienced problems with the fuel pump sending to much fuel to the engine at off throttle. The fuel pump control can be on/off or PWM

One of our trakbox testers has a megasquirt on his autocross turbo Miata. He highly recommended the tuning software. I am going to ping him @Tim240z

One of the most interesting things I learned researching the blog post was how Bosch actually developed and maintained two separate systems, one mechanical and one electronic, for use to license in production not wanting to gamble their market on the electronic version. However, once exhaust oxygen sensors became main stream, the mechanical version had no way to compensate and development subsequently ended.

Funding for this project is signed off with the following caveats: the system will be purchased and reviewed. The system will be installed and powered, the O2 sensor and stock FI sensors hooked up and logging will be done. Logging of the stock system performance to provide a base line for future development. Software will be evaluated and reviewed. The tech brief and work order will be issued in the coming weeks.

The rationale for this upgrade has been considered during the pending fuel tank upgrade scheduled for this fall / winter. Some additional work is planned for the fuel system including upgrades to the fuel lines and vent line. A fuel pump upgrade which could be controlled by the ECU is being considered. The engineering department considers this a safety and performance upgrade. During racing conditions the fuel is constantly being pumped up to the engine compartment where it is heated from extremely high engine compartment temperatures. When the throttle is closed, most of the fuel is returned to the tank. During constant running the temperature of the fuel in the tank rises.