Modifying fuel injection based on custom sensor

[hc08]

Let's say I have wired up a custom sensor to a Megasquirt 2 (v3.57 board) unit, and I have generated a correction factor for engine fueling based on the readings of this sensor using a custom .ini file. How would I actually go about applying this correction factor to the engine fueling? Let's also say for simplicity's sake that I have a single cylinder engine with only one injector.

[jsmcortina]

The microcontroller in the Megasquirt runs the engine, not your tuning computer. So, having data in TunerStudio doesn't help and won't allow you to do anything, unless I'm misunderstanding the question.

James

[Matt Cramer]

Upgrading to MS3 would let you use a blend curve between two fuel and ignition tables based on a custom sensor.

With MS2, you could pretend the second sensor was a baro sensor and use the baro correction curve for it, but that's about the only work-around I can think of with current code. The only other option would be to dust off your C and modify the firmware for this feature.

[hc08]

The microcontroller in the Megasquirt runs the engine, not your tuning computer. So, having data in TunerStudio doesn't help and won't allow you to do anything, unless I'm misunderstanding the question.

James

Am I correct in understanding that even if I have the custom sensor wired up to one of the spare inputs (i.e. adc7) of Megasquirt 2, I will not be able to actually affect the engine fueling because the microcontroller itself doesn't do anything with that data? So basically, all I can do with the sensor wired up and a custom .ini is just crunch some numbers and display them on a gauge in Tunerstudio?

Upgrading to MS3 would let you use a blend curve between two fuel and ignition tables based on a custom sensor.

With MS2, you could pretend the second sensor was a baro sensor and use the baro correction curve for it, but that's about the only work-around I can think of with current code. The only other option would be to dust off your C and modify the firmware for this feature.

If I already have a baro sensor and I want to retain it while simultaneously using the custom sensor, would I be able to multiply the two correction factors? I've already tried to include the correction factor from the custom sensor into the total correction variable (gammaEnrich), but apparently a statement like gammaEnrich = { gammaEnrich*CustomCorrection } is invalid.

[Matt Cramer]

If you are already using barometric correction, there's nothing in the MS2 firmware that will modify the fueling based on an analog sensor reading. TunerStudio can only display the sensor's reading, and if you get creative, do some math based on it. But the math can only be used for display and logging; it can't be sent back to the ECU. Actually having the sensor change the fueling would require modifying the MS2 firmware, or upgrading to MS3.

[hc08]

OK, thanks for the help on this topic. I don't know how to modify the firmware, so it looks like I won't be able to do what I want with a MS2.