Rich man EFIE

[Yucca]

Sylvain,

Just a little more info about DAC procedure on MCU:

If the input that you are feeding on the cars computer is reasonably high impedance, and I'm sure it will be, you can use your MCU PWM output through cap&res leaker and then feed that straight into your car computer.

In order to make this system work on all different car computers with different input impedances you would need a feedback loop. So have a spare ADC pin sample the signal you're feeding to the car computer and use a control algorithm to adjust the PWM in order to hold the exact voltage you require.

This method would allow you to drop out the opamp stage and it would still give rock steady voltage into everyones different car computers.

Fraser.

[TheOne]

> Stefans idea of flow rate transducer and realtime MPG display would make the device a real big seller I'm sure

Well, talking to the ECU is not an easy task, need more pin to do it, more complex board, more soldering etc... for 100$, its not thinkable with all the amount of work just to finish one, it cannot be under 200$...

Its good for a prototype but not for a final product to sell.

The best way is to manufacture a custom board with all the stuffs you are talking about, but its not an easy task and probably cost a lot.

Or the other way is to sell the programmed chip and lets the peoples make their own board using the instruction provided with the chip or on a website.

[Yucca]

> Stefans idea of flow rate transducer and realtime MPG display would make the device a real big seller I'm sure

Well, talking to the ECU is not an easy task, need more pin to do it, more complex board, more soldering etc... for 100$, its not thinkable with all the amount of work just to finish one, it cannot be under 200$...

Its good for a prototype but not for a final product to sell.

The best way is to manufacture a custom board with all the stuffs you are talking about, but its not an easy task and probably cost a lot.

Or the other way is to sell the programmed chip and lets the peoples make their own board using the instruction provided with the chip or on a website.

I don't think fuel consumption rate information can be read from the ECU, it would involve purchasing a flow rate transducer that outputs a signal that is proportional to the rate of flow of fluid through it, you then sample the sensor using ADC of MCU and then use a smoothing algorithm to give average flow or integrate to give total consumption. The only extra cost to your system would be the cost of a flow rate transducer that is petrol/diesel compatible.

The ECU interfacing is just for the EFIE which is what you are already doing.

[Almaz]

I'm working on a similar project.  Did you ever get to finish the project?  I'm just curious if you find a good enclosure for it. 
What do you think about
Control O2 sensors
Control MAP/MAF sensor
Show temperature of the cell
Maybe control IAT Sensor

Everything can be adjusted on the fly using LCD screen, using 16x2 or more lines.