Or you could spend a few cents on a resistor. Or if you wanted the same adjustability, a couple of bucks for a potentiometer would do the trick.

Freeware is available that lets you see how a honda ECM works. For certain models you can look at the fuel and ignition tables as well as IAT and ECT compensation levels. On a 75F day, fooling the ECU into thinking that the AIT is 0F will result in 21% more fuel to be delivered. That could possibly produce more power.

The same goes for ECT. When the coolant temp is 170F, fooling the ECU into thinking that the ECT is 0F will result in 75% more fuel to be delivered under full throttle conditions. That could also possibly produce more power.

Now if you want to deliver less fuel, on a 75F day, making the ECU think that the AIT is 150F or higher will result in a 6% decrease in fuel delivery.

This info is from my 93 Del Sol ECU programming. I have no idea how the Prius is programmed but one would think that there would be some similarities.

It's a Wonderful Day for Science!