NON-AIR FLOW CONTROLLED
See Figures 1 through 5
The Bosch Electronic fuel injection system used on all Type 3 models, and on 1971-74 Type 4 models (except 1974 models equipped with an automatic), consists of two parts. One part consists of the actual injection components: the injectors, the fuel pump, pressure regulator, and related wiring and hoses. The second part consists of the injection controls and engine operating characteristics sensors: a manifold vacuum sensor that monitors engine load, trigger contacts used to determine when and which pair of injectors will operate, three temperature sensors used to control air fuel mixture enrichment, a cold starting valve for additional cold starting fuel enrichment, a throttle valve switch used to cut off fuel during deceleration, and the brain box used to analyze information about engine operating characteristics and, after processing this information, to control the electrically operated injectors.
It is absolutely imperative that no adjustments other than those found in the following pages be performed. The controls for this fuel injection system are extremely sensitive and easily damaged when subject to abuse. Never attempt to test the brain box without proper training and the proper equipment. The dealer is the best place to have any needed work performed.
It is not recommended that the inexperienced mechanic work on any portion of the fuel injection system.
AIR FLOW CONTROLLED
1974 Type 4 models equipped with automatic transmission, as well as all 1975-81 Type 1 and Type 2 models, are equipped with an improved system known as the Air Flow Controlled Electronic Fuel Injection System. With this system, some of the electronic sensors and wiring are eliminated, and the control box is smaller. Instead fuel is metered according to intake air flow.
The system consists of the following components: