The more air coming into the motor (air volume) the greater the air mass, the higher the voltage has to be to keep the sensor at a constant voltage. It does this by sending a constant voltage across a wire in the air mass sensor, holding it at a constant temp. It measures the mass of the air coming in. The ECM does not measure the oxygen content of the air coming into the the engine. Perhaps you are relating your experience with carbuerated engines which have a whole different set of operating characteristics. Under WOT, there is a significant difference in performance with a less restrictive intake. If you are sucking in denser air, you will have to back off on the throttle to keep your car at some particular speed, decreasing the oxygen content per rpm to where it was before. The ECM meters fuel based upon the oxygen content and gives no more or no less than is needed. The oxygen content of the intake air has no effect on the efficiency of the engine or the burning of fuel under normal driving conditions. I have proven this myself with many vehicles that I have owned and modified myself. Given that, if the air going by the throttle place is more oxygen rich, the fuel will be burned more efficiently.When an engine runs more efficiently, it uses less fuel to create the same amount of power. When air is colder, the oxygen content is richer. Increasing horsepower at WOT is a whole different ballgame and not related to fuel economy.Ī cold air intake not only lets more air into the intake, the air is more dense.
The only way you can increase your gas mileage with a computer controlling your vehicle's gas injection is by changing your driving habits or increasing the inherent efficiency of the engine by decreasing friction, changing gear ratios etc. So, no matter what intake you have, you will still burn the same amount of fuel per mile to keep your engine at 50 mph. If the air is colder, you will just have a smaller throttle opening, but the amount of oxygen will still be the same, and so will the amount of gas injected to burn that oxygen. No matter how much air is available from some intake, your throttle is what limits what gets in to your engine. It only depends on how much air your throttle lets in - therefore, how much gas is metered by the ECM. You need a specific amount of gas to drive your vehicle at 50 mph and it is independent of the air intake properties. If you want to drive 50 mph, then you adjust your throttle opening to give you that. No matter how much air or how cold the air, the limiting factor in your intake is the throttle plate. The part I don't buy into is any increase in gas mileage which is the whole deal for 99% of the time driving. The more air and fuel you consume, the more horsepower you generate. That's a given by the nature of the beast.
If you can intake more air or colder air (same thing) then you will be able to make more horsepower at WOT. I don't agree with these supposed benefits of a CAI.