Discussion and questions related to the course Motorsport Wiring Fundamentals
My question may not be clear. However what I mean is, is it possible for us to say for example take an Evo X gsr and build a plug and play kit whilst retaining all factory features such as cruise control and all? And also is there a way to decode and make the standalone to work as with the factory CAN bus? What are examples of ECU manufacturers that can do so if possible?
It's possible using the MoTeC M1 Build system to create custom firmware to duplicate factory behavior on the CAN bus, and support all factory functions. MoTeC has done with with firmware packages for the Nissan GT-R, Honda Civic Type-R, Toyota FRS/Subaru BRZ and other. It takes a lot of work and effort to decode the factory CAN bus, (could by 1-2 man-years worth of effort), so you had better either really want it, or feels there is a large enough market to invest in the Research and Development required.
Like David said, anything is possible but how much time and money do you want to spend on it. It’s not just decoding the CAN. You also need to reverse engineer all of the control systems and algorithms behind the scenes that the vehicle busses are receiving and transmitting.
When looking at the problem there are basically two major components you need to divide it into. There is the hardware and there is the embedded firmware/software. Ecutek has basically made completely custom firmware for the GTR. They are using the factory hardware but all of the software is basically completely rewritten.
Generally speaking the only thing that makes standalone ECUs fairly limited is the fact that the firmware is the bare minimum. Much of the hardware used on a standalone ECU could more than likely run all of the OEM functions. Then there comes into the issue of does a company like say, Haltech want to provide every flavor of firmware for every car ever? This ultimately defeats the cost effectiveness of a standalone ECU that is kind of a “one size fits all” solution.
It depends on what you're trying to achieve, integrating with the OEM gauge cluster is relatively simple, it just requires a .dbc file - something that should already be present for a true plug and play standalone ECU. Things like cruise control are a little bit more involved as the aftermarket ecu will need to receive CAN inputs from the steering wheel and have capacity for PID speed control. OBD diagnostics is an independent protocol that takes OEM's a long time to develop so something that is rarely undertaken by aftermarket companies. Similarly with the ESP which requires integration with the ABS unit and ECU to manage torque reductions and brake applications so aftermarket ECU's tend to have a rudimentary TCS strategy, some take wheelspeed and acceleration data from the ABS unit but some only rely on deriving rpm gradient which is pretty useless in terms of finding laptime rather a safety net to tick a box.
There are companies and individuals out there that can re write the firm/middleware on OEM ECU's which is often the best option for full OEM integration and reflash tuning is also an option however this can be rather limited. For full integration a rather messy option but effective one is to keep the OEM ecu to manage the integration and use a standalone ECU like a piggy back so the standalone runs the engine and we feed the OEM ECU the signals it needs to satisfy all the ancillary functions, body controllers etc.
Be wary of companies selling plug and play ECU's and do your research, often they just mean its a generic unit with an adaptor harness. A true plug and play ECU will have been developed to integrate with the vehicle CAN bus and will run the gauge cluster at a minimum, all other functionality will be dependant of the development the manufacturer has put into the product.