Questions about Timing and AFR's

[Blue85]

The wideband sensors are Lambda sensors, so they're tracking distance from stoich, not actually measuring against 14.7 (they don't measure AFR at all!). Some engine management systems set the numbers correctly in terms of lambda instead of AFR. I suspect that what Go EFI is doing is looking for a wideband voltage that it associates to pure gas at that AFR, so in practice it's the same thing. For example, if you give it a 14.7:1 AFR target, it will adjust fuel until it sees 2.5V from the sensor. So if you move to E20 fuel, 2.5V will happen at 13.7:1 and the engine will run the same. Of course, it has to be allowed to learn after the change. The better way to do it is with a fuel composition sensor, but it's not that important when your Ethanol content is fairly consistent.

 

[anwat]

I actually have a lambada column on the datalogging software. Is it better to use that than the AFR calibration? There's a lot more to this than I had expected. So many different adjustments to make and each one impacts the rest. I'm starting to see why tuning a car properly is so difficult. Especially before the days of computers that could give you instant, accurate feedback on what changes you make are doing to the engine.