Firebird V8-305 5.0L (1982)
Mixture Control Solenoid: Description and Operation
The ECM controls the air/fuel mixture through the MC solenoid ground circuit--actuating the metering rods.
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When the MC solenoid is energized (down position), fuel flow is reduced providing leaner mixtures.
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When the solenoid circuit is open (up position), more fuel is allowed to flow, providing richer mixtures.
The ECM cycles the MC solenoid "ON and OFF" at a fixed rate of 10 times per second.
The air/fuel mixture is adjusted by varying the amount of time the solenoid is energized per cycle--solenoid dwell.
NOTE: Solenoid dwell can be read using most dwell meters. If engine operation changes when a dwell meter is connected to the mixture control
solenoid use a different meter. Meters with three leads are more likely to be able to measure solenoid dwell correctly than those with two leads.
