Port Fuel Injection

It was the standard petrol system for decades and is still used on many engines. Some engines combine port and direct injection to get the benefits of both. The fuel pressure is low, typically a few bar.

The injector sprays fuel onto the back of the intake valve where it mixes with air before entering the cylinder.

Port injection keeps the intake valves clean. Clogged injectors cause misfires and lean codes and can often be cleaned.