EEC IV Theory/Operation: Description

NOTE: This article contains information pertaining to the basic operation of the Ford Motor Co. EEC IV engine control system only. For testing with codes and diagnostic information see the following appropriate articles:

For 1.9L CFI, see: 1.9L CFI EEC IV TESTING
For 1.9L EFI, see: 1.9L EFI EEC IV TESTING
For 2.3L EFI/EFI Turbo, see: 2.3L EFI/EFI TURBO TESTS
For 2.3L HSC/EFI, see: 2.3L HSC/CFI TESTING
For 2.5L HSC/CFI, see: 2.5L HSC/CFI TESTING
For 3.0L EFI, see: 3.0L EFI EEC IV TESTING
For 3.8L CFI, see: 3.8L CFI EEC IV TESTING
For 5.0L SEFI, see: 5.0L SEFI EEC IV TESTING

The center of the EEC-IV system is the Electronic Control Assembly (ECA). The ECA receives information from various sensors and switches. Based on information received and the operation program in the ECA's memory, the ECA generates output signals to control engine operation.

The calibration module for EEC-IV system is mounted inside the ECA. The ECA is located in one of the following locations: under dash behind right kick panel, under dash on left side of steering column, or on left rear corner of engine compartment (below windshield wiper motor).

The EEC-IV system controls 3 major areas of engine operation: air/fuel mixture, ignition, and emission control. Additionally, the system can control A/C compressor clutch operation and idle speed. The system provides self-diagnostic capabilities.

The air/fuel mixture control is accomplished by an airflow controlled, multi-point fuel injection system on 1.9L EFI, 2.3L EFI, and 2.3L EFI/Turbo models. Escort, EXP, and Lynx models equipped with the 1.9L CFI engine use a central fuel injection system. Sable and Taurus models equipped with the 2.5L HSC/CFI engine use a central fuel injection system, as well as a 3.0L EFI (multi-point fuel injection) engine. Tempo and Topaz models with the 2.3L HSC/CFI engine uses central fuel injection, as do all models with a 3.8L CFI engine. All 5.0L SEFI engines use sequential electronic fuel injection.

The EEC-IV ignition system is controlled by the ECA through a Thick Film Integrated (TFI-IV) ignition module. Ignition timing (advance or retard) and dwell are controlled with this system to improve ignition system performance. The ignition coil is an "E-core" version and replaces the earlier oil filled coil.

Emission control components controlled by this system include EGR and canister purge. These systems are normally off, but are turned on when the engine is ready to operate with the mixture change caused by EGR and canister purge operation.