Fuel Delivery and Air Induction: Description and Operation

Sequential Multiiport Fuel Injection:

SEQUENTIAL MULTI PORT FUEL INJECTION

Sequential Multiport Fuel Injection (SMPI) goes a step further in fuel delivery precision. By providing separate Engine Control Module (ECM) ground controls for each injector, SMPI provides control of individual injectors.

The SMPI system allows the supply of fuel to be matched to the specific needs of each individual cylinder. It also requires that injector operation be precisely timed to valve operation. The ECM in an SMPI system uses additional inputs, over and above those found in an MFI system, to control injector operation.

SMPI is featured on vehicles using the Generic Engine Management System (GEMS).

Basic Fuel Injection System:

FUEL SYSTEM COMPONENTS

The following components are included in the fuel injection system:

- Engine Control Module (ECM)
- Heated Oxygen Sensor (HO2S)
- Fuel Pump (FP)
- Fuel Filter
- Fuel Pressure Regulator
- Fuel Injectors

Additional components are used to monitor and control the "air" portion of the air/fuel mixture. These are listed below:

- Mass Air Flow Sensor (MAFS)
- Throttle Butterfly
- Throttle Position Sensor (TPS)
- Idle Air Control Valve (IAC)