Almost all cars today contain fuel injection systems, which provide much better control over your engine's performance than the carburetors in older cars provided. Yet even with the better control capabilities, your fuel injection system does not have what it takes to respond to real-time changes all on its own. Instead, the engine control unit gathers information about your car's performance.
If you would like to learn more about the various processes governed by an engine control unit, keep reading. This article will outline three of the most important jobs performed by this vital component.
1. Adjusting Air-Fuel Ratio
Most fuel injection systems disperse gasoline into the intake manifold through spray nozzles. There, the gas mixes with the stream of air flowing into the intake manifold. The manifold's low pressure causes the liquid gasoline to quickly vaporize into a gas, which mixes together with the air before entering the cylinders of the engine.
The air-fuel ratio plays one of the largest roles in determining engine efficiency. Too much or too little fuel relative to the air supply leads to rich or lean fuel, respectively. Both of these issues can result in poor fuel economy, as well as performance issues that include rough idling, misfiring, and lack of power.
The engine control unit ensures that the air-fuel ratio remains within acceptable limits at all times. Using information received from sensors, the control unit adjusts the amount of fuel entering the intake manifold through the injector nozzles. This amount will vary depending on environmental factors as well as on the speed of your car.
The engine control unit also dictates the fuel injectors' timing, both in terms of when they release the gasoline and how long they remain open. In this way, the engine control unit ensures that the fuel has enough time to thoroughly disperse and mix with the air before entering the engine.
2. Regulating Ignition Timing
An engine control unit's governing power extends far beyond the fuel injectors themselves. The control unit also regulates the activity of your engine's spark plugs. The spark plugs, as you probably know, release tiny jolts of electricity in the cylinders. This electricity causes the air-fuel mixture to combust.
Ideally, combustion should occur just at the moment when the piston has compressed the air-fuel mixture completely. Ensuring such precise timing can be tricky since a split-second gap occurs between the releasing of the spark and the actual moment of combustion.
Releasing the spark too soon or too late means that the air-fuel mixture's pressure will not be at its maximum state. As a result, combustion will not generate as much power.
The engine control unit monitors the position of the piston by means of a crankshaft position sensor and also monitors the timing of the spark plugs. By collating these two sets of information, and accounting for the slight combustion lag, the engine control unit can regulate the spark plugs to ensure optimal timing.
3. Controlling Idle Speed
The engine control unit constantly monitors and responds to engine conditions - even when your car is simply idling. Of course, idle speeds vary too, depending on the environmental constraints and by things such as running the air conditioner, which requires an extra amount of power from the engine.
The engine control unit sizes up all these factors and determines the most appropriate idle speed to meet a given set of circumstances. The control unit seeks to keep idle speeds as low as possible to conserve fuel, yet not so low as to cause the engine to stall.
Few parts of a modern car hold quite the same level of importance as the engine control unit. For information about what it takes to keep your engine control unit working smoothly, please contact the pros at Walnut Creek Import Service and Sales.