On these engines, their control system is considered as part of the emission control system. Major components include carburetors, feedback control system, air intake system, accelerator control system and EGR system. The heart of the engine and emissions controls is the carburetor and electronic air control valve (EACV). Other parts of the system are sensors and switches that provide information to the on-board computer, which in turn opens and closes several solenoid valves and the EACV to maintain the ideal air-fuel ratio in the air-fuel mixture under all engine operating conditions. The catalytic converter used on carburetor engines is identical to that on fuel injected engines.
When maintaining and repairing an engine management system, it is very important to know when and under what conditions a problem occurs. At high speed? At idle? Only at high load or at high acceleration? In wet weather? After receiving answers to a detailed questioning, you roughly determine the damaged system. Clarity and certainty in the formulation of the problem will help to exclude many systems from inspection as serviceable, and, conversely, quickly identify the faulty one. Before you decide that the electronics are faulty, make sure that all vacuum hoses are intact and electrical contacts are not rusted or shorted by abandoned tools. Very often, just when connecting and disconnecting, rust is knocked off the contact and the operation of the device is restored. Be sure to check everything properly, especially if the car has undergone several major repairs.