Port Fuel Injection
A fuel injection system where injectors spray fuel into the intake ports rather than directly into the cylinder.
Port Fuel Injection (PFI), also known as multi-port fuel injection, is a fuel delivery system where fuel injectors are located in the intake manifold runners, pointing directly at the back of each cylinder's intake valves. In this system, fuel is sprayed and mixed with air before entering the combustion chamber.
One of the major advantages of PFI is that the gasoline-and-additive mixture flows over the intake valves, washing them clean of engine oil vapor and combustion residues. This prevents the carbon buildup common on the intake valves of direct-injection engines. However, PFI is less efficient than direct injection because fuel can cling to the runner walls, and the system cannot control combustion as precisely.
Symptoms of PFI system issues include clogged fuel injectors causing lean codes, hard starting, and rough idling. Mechanics test PFI systems by checking fuel pressure and using a noid light to verify the electrical pulse signals to each injector. Regular fuel system cleaning additives can help keep PFI injector tips free of deposits.