EFI 101, Basic 4-Cycle Engine & ECU Operation and Tuning Rhetoric
by Christian Krahenbuhl
Automotive engineering involves a series of compromises. The compromise of designing affordable, durable, and fuel efficient engines that are enjoyable to drive while meeting modern emissions regulations has made the job of EFI controls very complex. Affordability and durability are concerns because manufacturers and consumers have limited resources. An engine designed to use some super metal like unobtainium (Uo and atomic number of 666) would be ideal. Engines using unobtainium make 1000+ horsepower, require tune-ups at 1,000,000 mile intervals, and get well over 100 miles per gallon while running on sea water and emitting drinking water and oxygen out the tailpipe. Hopefully you've figured out that unobtainium engines were created out of my friend's imagination. The point is, the best engine designs using the most exotic materials and manufacturing processes are expensive and can be afforded by the wealthy few.
Most of us drive commuter cars in diverse environments (cold and hot, humid and dry, low and high elevation) and have very little control of the fuel we put in the tank…yet our expectations are that the engine fires up every time and runs perfect under all conditions. Even if we put crap gas into the tank (with our knowledge or not) or don't maintain the car as suggested by the manufacturer, we expect the car to accelerate like a race car and get the same gas mileage it did on its best day. I chuckle now recalling various stories from friends explaining how their wifes or relatives filled their diesel cars or trucks with petrol. Yes, petrol (pump gas) and diesel are both fuels, but they are different enough to cause serious damage when run through the improper engine.
An engine's design must take into account these factors which means the engine and control systems must be just about bomb-proof and need to be able to deal with human error…which is nearly impossible. Designing an engine that is enjoyable to drive while meeting modern emissions regulations is the more creative aspect of automotive engineering. We've proven we can make power with the modern internal combustion (IC) engine design. Top-Fuel dragsters make around 1000HP per cylinder. Using your four or six cylinder commuter car with that amount of power would be enjoyable, but consuming over 20 gallons of fuel and emitting raw fuel and fire to get you a few blocks down the road in an uncontrollable manner is not reasonable. Now take into account that the engine would likely need to be fully rebuilt with all new hardware prior to making it through the next few blocks gives you an idea about what compromises automotive engineers needs to take into account for their designs. Simply put, vehicle manufacturers design cars so they can be manufactured and sold at a profit and so people whom buy cars can afford not only the car, but the fueling and maintenance costs while they own the vehicle.