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.
Closed Loop Mode
During this mode, EFC is operational and continuously corrects the air/fuel mixture toward 14.7:1 (best emission control ratio).
When the combustion computer receives signals from the oxygen sensor, and the throttle switch indicates the engine is not at idle, the computer sends a signal to the carburetor solenoid or vacuum regulator solenoid, causing the air/fuel ratio to be changed. This cycle repeats continuously to ensure proper mixture control at all times.
In addition, during the Closed Loop Mode, this system offers the built-in ability to maintain a constant air/fuel mixture regardless of altitude, because of its oxygen-sensing operation.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.