Powertrain Management: Description and Operation

PURPOSE
The Hot Wire Multiport Fuel Injection (MFI) system derives its name from the Mass Air Flow (MAF) sensor which uses one cold wire and one electrically heated wire to measure the volume of air entering the engine.

The function of the system is to supply the exact amount of fuel directly into the intake manifold according to the prevailing engine operating conditions.

OPERATION
To monitor these conditions, various sensors are fitted to the engine to measure engine parameters. Data from the sensors is received by the Engine Control Module (ECM). The ECM will then determine the exact amount of fuel required at any condition.

The ECM having received data from the sensors produces pulses, the length of which will determine the simultaneous open time of each bank of injectors in turn, which will govern the amount of fuel injected.

The ECM provides precise control of fuel injection and emission control systems to ensure optimum performance and strict emissions compliance.


Various engine sensors and other systems supply the ECM with operating information. The ECM processes the sensor input and sends output signals to adjust injector pulse width.

Input signals include:
^ Engine Speed
^ Airflow Volume
^ Engine Temperature
^ Throttle Position
^ Lambda Signal
^ Battery Voltage
^ Vehicle Speed
^ Gear Position
^ A/C Signal


Output Signals include:
^ Fuel Injection Control
^ Idle Speed Control
^ Fuel Pump Control
^ Evaporative Control


ON-BOARD DIAGNOSTICS
In the event of a system malfunction, a fault code will be stored in the ECM, and can be retrieved. Refer to How to Display and Read Diagnostic codes in Computers and Control Systems. Reading Diagnostic Trouble Codes