It's a high performance modern 2.0l engine 125 kw 202 nm of torque. (ISO)
It boasts an elecronic Throttle Body, Pre and Post Cat Oxygen Sensors and Knock control and Gasoline Direct Injection. It's faster than the Mazda3 2.0 without GDI.
It also uses an ECU to monitor and control ignition, Fuel ,AIR intake and Valve timing on both Cams.
Basically the way it works is that it controls fuel and air to archieve a mixture ratio of 14.7 Air to 1 Fuel. This is called the stoichiometric air/fuel mixture.
This was clearly stolen from a writeup on the engine.
For gasoline fuel, the stoichiometric air/fuel mixture is approximately 14.7; i.e. the approximate mass of air is 14.7 mass of fuel. Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture.
Millions of $ have been spent to develop the Focus engine and now we think that we can fool the ECU by having a less resistant air filter.
It will just take less air because it is in control of the throttle body not the driver. (there is no accelerator cable.)
The only thing in this quote that is correct is that 14.7 is stoich. Under very light loads the ECU will keep that AFR in the 14.7 range, however under higher loads running at 14.7 will result in melted components. The tune I'm running in my Mazda is targeting 12:1 under heavier loads, and even that's considered to be aggressively lean. Leaning out the AFR is one of the ways you make power, but leaning it out to much can turn you engine into a very expensive paper weight from high compustion temps. To consider everything below 14.7:1 lean and everything about rich is ok as long as you're not talking about a gas engine.
You are sadly mistaken about the concept of throttle by wire. The throttle isn't controlled by the ECU its still controlled by your foot. The ECU simply adapts the other engine perimeters to the given throttle input. In some cases you'll find car manufactures who use throttle by wire to limit the actual throttle percentage for different reasons. My Mazda has a throttle restriction under 60MPH because the torque steer can be a bit overpowering for some.
In fact with these modern engines,even if you drive it without an air filter you will find little or no improvement in power. You will however get a lot of induction noise.
(please don't try this at home as you could damage your engine by sucking dirty air into the cylinders).
The extra induction noise on these aftermarket filters might give you the feeling that you have more power because you hear more noise.
No production vehicle takes air from the engine comparment, Cool air with some moisture is heavier than hot air. It helps the fuel to burn more completely. Motor Manufacturers have gone to great lengths to design an airbox system that takes cool air from outside the vehicle, they pay their engineers a lot of money to do this. now we come along and want to undo what years of research and development have archieved.
Yes, engines like cooler air. They like cooler air because its denser than hot air and more fuel can be added into to mix. More fuel = more energy (Providing you keep and effective ratio to air) = more power. Its not because it helps the fuel burn of completely.
Automotive engineers design engines with a mix of performance, fuel efficiency, comfort, longevity and cost depending on the application. In the case of an intake system they're going to try to muffle the engine because 99% of people would consider a loud intake to be annoying. So they do this by adding resonators and other types of noise canceling devices which cause restriction in the intake system. The same goes with exhaust system. Engines are designed for people who want quiet, fuel efficient, and reliable engines, and not the 1% who value performance most.
To get more power to the wheels an ECU remap would have to be done.
What these ECU remaps do is to overfuel at low revs to give you more power.
(Just like in the morning when the engine is still cold).
Another Option is a Turbocharger with ECU Remap, Just trade it in for an ST and make sure that you get a manual gearbox. Auto boxes rob your power by changing up too early.
If you rev this engine to 4000 revs before changing gear it's got a nice powerband between 2500 and 4500, (This is where the torques are hidden) if you change gears at 2000 then it's a limp dog.
Tunes are a very effective way to gain power and ever fuel efficiency out of an engine. (By your logic its stupid to try because engineers spend years developing tunes right????) On a naturally aspirated engine most of the power is usually gained by leaning out the A/F ratios within reason. Making the engine run rich usually has the opposite effect. Also fueling is more load based than RPM, the RPM is just a multiplier.
Rich = safe
Lean= Fun
Getting a custom tune is always a good idea when you start modifying the engine. The ECU has a limited ability to adapt to changes made, it usually takes a tune to get the ECU back on track, even with just and intake. MAF tables are usually only able to adapt to changes in air flow from a clean filter to a dirty one. Depending on the engine an aftermarket intake can dramatically increase airflow this can mess with the MAF calibration and cause the ECU to make fueling corrections using the fuel trims.
