This post documents the development of version 1 of the ECU tester. This has since been replaced with version 2.

Here is a block diagram of what the first attempt at a test system will look like.

PCB designed.

It is menu driven over a serial port and here is what that looks like:


   1. Show current settings
   2. Off
   3. Cranking
   4. Cold idle
   5. Hot idle
   6. Cruise 30MPH
   7. Cruise 70MPH
   8. Gentle acceleration
   9. Moderate acceleration
  10. Hard acceleration
  11. Set coolant temp
  12. Set air temp
  13. Set engine speed
  14. Set throttle
  15. Set pulse generator dwell

Enter a number and press Enter:

The temperature sensors are simulated using the Steinhart-Hart equations with the coefficients provided by Brad.

It has two generic 5V/12V active high/low outputs for controlling a vacuum system. Currently that is not used and the idea is a Mityvac is manually set to the target pressure, but the support is there on the board if we need it later on.

While the ECU is being tested we need to manage the injectors, keeping them cool and lubricated. Here is my idea for this – a test stand.

An 80mm PC case fan blows air across the injectors. A barbed connector allows Seafoam, Techron, etc. to be gravity fed into the injectors to lubricate them. The spray from the injectors comes out of another barbed connector. I guess a small electric pump could be used to recirculate the fluid, if needed. I’m not sure how much fluid they will suck in under gravity compared to under pressure.

The design is modular so an additional fan to pull air can be added if needed and the fluid collector on the bottom can be removed.

All 3D printed. The body that holds the injectors will be printed out of TPU as that can withstand higher temperatures.

Here is the complete setup (courtesy Cush).

Video part 1:

Video part 2:

All of the source files can be found on github here.

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