Quote:
Originally Posted by jedibow
Sorry, only certain ECU's are proactive to determine what ignition timing and fuel tables to run, namely Toyota, Subaru, and Volkswagen mostly. Most ECU's are reactive, and only retard ignition as they see knock, so the maximum timing it will run will be the value on the timing map (they cannot exceed these values) unless effected by a multiplier table such as barometric pressure, or tempurature adjustment tables.
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One thing to keep in mind is that an ECU really consists of 3 things:
1) Hardware (injector drivers, analog inputs, CAN communication, processor, RAM, flash ROM, etc)
2) Software (the way things are calculated, not the actual values in the tables)
3) Software calibration (the tuning of the maps and values inside)
Software is being developed all the time, but it's not always changing on every engine. If you've got an old engine on a vehicle that doesn't change much, it may have old software. That cold mean old knock control logic that is mostly reactive in nature. The manufacturer isn't going to update it unless they feel it's necessary to meet an emissions, engine output, or driveability/NVH (noise/vibration/harshness) goal--development time costs money.
Look at the WRX and STi for example. The main non-emissions calculations inside have barely changed in 10 years. Some stuff shifted around when they went to electronic throttle, AVCS (variable valve timing) and a 32bit ECU, but that's about it. The EJ series engines are 20+ years old.
When a mostly new engine goes into development, you can expect some of the newest software to be implemented. So it's less about the make (Toyota etc) and more about the individual needs of the vehicle under development.
Btw, much of this software is developed in collaboration with suppliers or purchased off-the-shelf. Sometimes most of the engine tune is outsourced to a company and you never hear about it. Here is a partial list of the main suppliers of ECU and ECU software/control logic:
Denso
Yakazi
Hitachi
Delphi
Siemens/Continental
Bosch
Magnetti Marelli
Renesas
Most German makes use Bosch or Siemens. Toyota uses Denso on almost all engines; Subaru uses Denso a lot but dabbles in other brands. Nissan uses Hitachi. Hyundai uses Siemens. GM uses Delphi and Bosch mostly; Chrysler uses Magnetti Marelli stuff. I don't know every supplier used on every project, but it's perhaps half true to say something like "Volkswagen ECUs respond better to low octane than others." VW/Porsche use various versions of Bosch software anyway.
Hope that clears some things up.