Programmed Fuel Injection System (PGM-FI)
In the PGM-FI system, electrical pulses of a clearly defined duration are used to control the injection of fuel through injectors directly into the intake port of each of the engine's combustion chambers. The moment and duration of opening of each of the injectors is controlled by the powertrain control module (PCM). The PCM continuously monitors various engine operating parameters and, based on the incoming information, determines the required volume of fuel injected into each of the intake ports. In this case, the throttle body serves only to control the supply of air to the fuel supply system. Due to the fact that each of the cylinders is equipped with its own injector, this scheme provides the ability to very accurately control the composition of the air-fuel mixture.
Fuel pump and fuel lines
Fuel is supplied from the fuel tank to the injection system and its excess is returned back to the fuel tank via two metal lines laid under the bottom of the car. The submersible electric fuel pump is located inside the fuel tank and is combined into a single assembly with the fuel flow sensor unit. The fuel vapor return system carries out the removal of fuel vapors back to the fuel tank via a separate return line. Access to the fuel pump/fuel flow sensor assembly is carried out through the luggage compartment of the car by dismantling the plastic cover.
The PGM-FI main relay (fuel pump relay) is mounted on a bracket under the instrument panel on the driver's side of the vehicle, to the left of the steering column. The relay is controlled by several different electrical circuits. One of these circuits is supplied with battery voltage from the ignition switch. The second circuit is connected to the PCM, which closes the relay for one second. During engine cranking, the PCM closes the relay to ground until the piston position sensor (CYP) provides a signal (see Chapter Engine management). If there are no reference pulses for two to three seconds, the pump is switched off. The third circuit de-energizes the relay when the clutch pedal is released (models with manual transmission), or when the AT selector lever is moved out of the "P" position. Protection of this circuit from overloads is provided by a 7.5 A fuse.
Exhaust system
The exhaust system of V6 models consists of a pair of exhaust manifolds, a Y-shaped downpipe, a catalytic converter with an oxygen sensor (l-probe) located behind it, a muffler and a downpipe. On 4-cylinder models, the exhaust system design is even simpler, since the catalytic converter is connected by a downpipe to the engine's single exhaust manifold.
The catalytic converter is one of the main components of the exhaust gas toxicity reduction system. The models in question use single-section converters with a 3-functional catalyst.
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