EEC IV THEORY/OPERATION -1985 Ford Pickup F150
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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 the passenger compartment, in one of the following locations: under the center console, under dash on left side of steering column, under passenger seat, or under dash behind right kick panel.
The 2.3L and 5.0L EFI models use the Bosch/Ford Electronic Fuel Injection system (EFI). The EFI system is classified as a multi point, pulse time, speed density, fuel injection system. The EEC-IV computer accepts inputs from various engine sensors to compute the required fuel flow rate necessary to maintain a prescribed air/fuel ratio throughout the entire engine operational range. The computer then outputs a command to the fuel injectors to meter the appropriate quantity of fuel.
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.
On all other models, the air/fuel mixture control is accomplished by use of a feedback carburetor (FBC). The ignition system is controlled by the ECA through a Thick Film Ignition (TFI-IV) module. Ignition timing (advance or retard) and dwell are controlled with this system to improve ignition system performance.
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.
Tuesday, August 5th, 2008 AT 3:19 PM