In SX Microcontrollers, SX/B Compiler and SX-Key Tool, John Bond wrote:

What a fascinating project!!!

The way I understand it, there are a number of factors affecting your fuel flow in a motor. In an ideal engine management system, I guess these would be:

-	Throttle setting, The wider the throttle the greater the fuel flow

-	RPM, The higher the speed, the greater the flow. This is probably not
                linier because low RPM, wide throttle, heavy torque needs a good flow

-	Acceleration, you need a spurt as you open the throttle. The quicker
                you open it the bigger the spurt, (remember the tuners rule - run
                engine rich on acceleration)

-	Temperature of the air, atmospheric pressure and humidity.

-	Temperature of the motor. Remember the bigger the difference
                between engine temperature and inlet air temperature, the more air the
                engine breaths so you need a bit more fuel

-	Valve timing, the more aggressively the exhaust valve opens the more
                fuel you need. Trouble is this is not uniform over the full RPM range but
                varies depending on the harmonics on the exhaust valve and the 
                exhaust manifold. The same is true on the inlet valve.

-	Engine condition, compression, wear, how clean the air filter and plug
                are, etc

-	Quality of fuel, RON number (for knock) and calorific value (power of
                the fuel), how well it atomizes. (probably not a problem in the USA)

Now obviously you're not building an Indy 500 engine so a lot of these can be left out. I have two questions:

Is it possible to address most of these by monitoring only throttle, RPM, temp and CO2?
If you were to add sensors, what would they be?

To think you're doing all this with just 1 microprocessor chip!!! All the new commercial systems I've seen seem to favor one controller for ignition, one for injectors one for peripheral components, (and often one specifically for the gear box!!!).All this is tied together with LinBus or some bastardized CanBus.

John Bond

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