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.
Feedback Control System
Carburetor Feedback Control (FBC) system maintains a controlled air/fuel ratio which allows catalyst to reduce HC, CO, and NOx in addition to providing better driveability and fuel economy. Exhaust gas is monitored by an Electronic Control Module (ECM) by way of an exhaust manifold mounted Oxygen (O2) sensor. ECM processes O2 sensor signal and adjusts air/fuel ratio through a mixture control solenoid in the carburetor.
The ECM, located under the glove box, controls fuel-cut system, idle-up system, bowl vent system, EGR system and secondary throttle valve system, as well as the feedback system.
ECM controls this function through the following received signals: O2 sensor, engine coolant temperature (thermal) switch, throttle position (wide open and idle) switch, engine speed, electrical load, gear position, altitude compensation and engine compartment temperature. See Fig 1 .
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.
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