Nubira SX Hatchback L4-2.0L DOHC D-TEC MFI (1999)
Fuel Injector: Description and Operation
FUEL INJECTOR
The multi-port fuel injection (MPFI) assembly is a solenoid-operated device controlled by the powertrain control module (PCM)/engine control module
(ECM). It meters pressurized fuel to a single engine cylinder. The PCM/ECM energizes the fuel injector or the solenoid to a normally closed ball or
pintle valve. This allows fuel to flow into the top of the injector, past the ball or pintle valve, and through a recessed flow director plate at the injector
outlet.
The director plate has six machined holes that control the fuel flow, generating a conical spray pattern of finely atomized fuel at the injector tip. Fuel
from the tip is directed at the intake valve, causing it to become further atomized and vaporized before entering the combustion chamber. A fuel injector
which is stuck partially open will cause a loss of fuel pressure after the engine is shut down. Also, an extended crank time will be noticed on some
engines. Dieseling can also occur because some fuel can be delivered to the engine after the ignition is turned OFF.
