Feedback Carburetor System: Description
The Electronically Controlled Carburetor (ECC) system is a computerized emission and fuel control system. The system is used on all Federal models without 4WD and all California models.
Two versions of the ECC system are used on Subaru models, depending upon carburetor application. One system is used with Hitachi carburetors and another system is used with Carter carburetors. All California models are equipped with Hitachi 2-barrel carburetors. Federal models without 4WD can be equipped with Carter 1-barrel or Hitachi 2-barrel carburetors.
The ECC system controls engine operation and lowers exhaust emissions while maintaining good fuel economy and driveability. The Electronic Control Module (ECM) is the "brain" of the ECC system. The ECM controls many engine related systems to constantly adjust engine operation.
The ECC system is primarily an emission control system, designed to maintain an ideal air/fuel ratio of 14.7:1 under all operating conditions. When an ideal ratio is maintained, the catalytic converters can control carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) emissions.