Theory/Operation - CARBURETED: Introduction
NOTE:
This section covers the basic description and operation of engine performance related systems and components. Prior to diagnosing vehicles or systems with which you are not completely familiar, read through this section.
Feedback carburetor engine control systems monitor vehicle operating conditions (input signals) and regulate the air/fuel mixture and other engine control operations (output signals) to lower exhaust emissions, while maintaining fuel economy and driveability.
The control systems have a built-in fail-safe mechanism. If a fault occurs while driving, the system will substitute pre-programmed values. Driving performance will be affected, but the vehicle may still be driven.
Fuel injected systems also have a self-diagnostic feature. These systems have the capability of recognizing a system fault and storing a related trouble code in memory for future diagnosis.