Powertrain Management: Description and Operation

PURPOSE
Computerized Engine Control (CEC) Systems electronically regulate the air/fuel mixture, idle speed and ignition timing to achieve optimum[1] engine performance.

INFORMATION STRUCTURE
Information in this section is divided into the following four major sub-headings:

COMPUTERS AND
CONTROL SYSTEMS Addresses the on-board computer system and components as related to engine management. Consult this section for information regarding on-board diagnostics, sensor inputs, computer outputs, etc.

EMISSION CONTROL
DEVICES Addresses emission related systems and components only. Includes (but is not limited to) Exhaust Gas Recirculation (EGR) systems, Evaporative Emission (EVAP) systems, Positive Crankcase Ventilation (PCV) systems, Exhaust Emission controls, Air Injection Systems (AIS), etc.

FUEL SUPPLY AND
AIR INDUCTION
SYSTEMS Focuses on systems and components related to fuel and intake air delivery. Does NOT include information regarding electronic engine controls.

IGNITION SYSTEM Focuses on primary and secondary ignition systems and components. Does NOT include information regarding electronic engine controls.

TRANSMISSION CONTROL
SYSTEMS Automatic transmissions on this vehicle have specific computer controls of shift patterns and control pressures. Separate diagnostic codes are used for diagnosis of the transmission control system. Consult this section for information regarding on-board diagnostics, transmission sensor inputs, outputs, diagnostic codes, etc.

[1] Optimum performance means the best possible compromise between the demands of high power, low fuel consumption, and the cleanest possible exhaust emissions.


ABBREVIATIONS:


ALDL Assembly Line Data Link
ATS Air Temperature Sensor
CCP Controlled Cannister Purge
CTS Coolant Temperature Sensor
CPS Crankshaft Position Sensor
DIS Distributorless Ignition System
ECM Engine Control Module (now referred to as PCM)
EEPROM Electronically Eraseable Programable Read Only Memory
EST Electronic Spark Timing
EVO Electrical Variable Orifice
HWS Handwheel Sensor
IAC Idle Air Control
IACV Idle Air Control Valve
I/P Instrument Panel
MAP Manifold Air Pressure
MAT Manifold Air Temperature
MFI Multi-port Fuel Injection
PCM Powertrain Control Module (Previously called ECM)
[1][2]PCV Positive Crankcase Ventilation
PSPS Power Steering Pressure Switch
SIR Supplemental Inflatable Restraint
TCC Torque Converter Clutch
TPS Throttle Position Sensor
VSS Vehicle Speed Sensor