A car engine runs on petrol or diesel. Or on electricity. On a gasoline engine, a carburetor or electronic injection ensures that the engine receives fuel in just the right amount. A diesel engine always has injection and an electric motor has a power supply. Carburettors are actually no longer on cars. They are still used on motorcycles, mopeds and scooters, for example.
A carburetor can be adjusted manually. Propellers control the idle speed and the amount of air. A nozzle determines the amount of fuel.
The carburetor mixes that fuel and air and that air mixture enters the cylinders. There it is ignited. The electronic injection does exactly the same, it also mixes fuel with air but in a completely different way. There is nothing to adjust manually on an electronic injection. That is what the electronics developed for this purpose do.
An electronic injection is also adjusted while driving and that has advantages. In this way, the optimum amount and composition of fuel/air can be supplied to the cylinders under all kinds of circumstances. Various sensors monitor things such as the engine and outside temperature, the composition of the exhaust gases in relation to the environment, the speed and, for example, the altitude at which the car is driving, because this indicates how much oxygen is in the air. All factors that a modern car engine takes into account in order to perform well and economically.
The electronic injection in cars is regulated and controlled by a computer: the engine management computer. That computer can be influenced, but that is not necessary in principle. It works or is defective. In that case, a new computer will have to be installed. However, it is possible to tune car engines by setting the computer differently. Tuning, yes chip tuning mentioned is changing values so that more power is delivered by the engine or that the tractive effort is increased. Tuning is usually only useful for turbocharged and diesel engines.