Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1990RANGER 4WD L4-140 2.3L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSDESCRIPTION AND OPERATIONEFI & SEFI ENGINESAIR SUB-SYSTEM
1990 Ford Ranger 4WD L4-140 2.3L SOHC
Air Sub-System
1990 Ford Ranger 4WD L4-140 2.3L SOHCSECTION Air Sub-System
The air sub-system consists of an air cleaner, an air cleaner valve assembly, vane meter, throttle air bypass valve and air tubes.
Air entering the engine is measured by the vane meter located between the air cleaner and throttle body assembly.
The output of the vane meter is applied directly to the ECA to assist in determining the correct air/fuel ratio. The vane meter consists of two separate sensors, a vane airflow (VAF) sensor and a vane air temperature (VAT) sensor.
The throttle air bypass valve regulates the amount of air which flows around the throttle plate to control engine idle speed.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.