Rodeo S 2WD L4-2.2L (1999)
Fuel Metering System: Description and Operation
Fuel Metering System Modes
Acceleration Mode
Acceleration Mode
The PCM provides extra fuel when it detects a rapid increase in the throttle position and the air flow.
Battery Voltage Correction Mode
Battery Voltage Correction Mode
When battery voltage is low, the PCM will compensate for the weak spark by increasing the following:
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The amount of fuel delivered.
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The idle RPM.
Clear Flood Mode
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal down all the way. The PCM then de-energizes the fuel injectors. The PCM holds the fuel
injectors de-energized as long as the throttle remains above 80% and the engine speed is below 800 RPM. If the throttle position becomes less than 80%,
the PCM again begins to pulse the injectors ON and OFF, allowing fuel into the cylinders.
Deceleration Fuel Cut Off (DFCO) Mode
Deceleration Fuel Cut Off (DFCO) Mode
The PCM reduces the amount of fuel injected when it detects a decrease in the throttle position and the air flow. When deceleration is very fast, the PCM
may cut off fuel completely for short periods.
Engine Speed/Vehicle Speed/Fuel Disable Mode
Engine Speed/Vehicle Speed/Fuel Disable Mode
The PCM monitors engine speed. It turns off the fuel injectors when the engine speed increases above 6000 RPM. The fuel injectors are turned back on
when engine speed decreases below 5750 RPM.
Fuel Cutoff Mode
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the ignition is OFF. This prevents engine run-on. In addition, the PCM suspends fuel delivery it no
reference pulses are detected (engine not running) to prevent engine flooding.
Run Mode
Run Mode
The run mode has the following two conditions:
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Open loop
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Closed loop
When the engine is first started the system is in open loop operation. In open loop, the PCM ignores the signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP, ECT, and MAF sensors.
The system remains in open loop until the following conditions are met:
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The HO2S has a varying voltage output showing that it is hot enough to operate properly (this depends on temperature).
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The ECT has reached a specified temperature.
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A specific amount of time has elapsed since starting the engine.
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Engine speed has been greater than a specified RPM since start-up.
The specific values for the above conditions vary with different engines and are stored in the programmable read only memory (PROM). When these
conditions are met, the system enters closed loop operation. In closed loop, the PCM calculates the air/fuel ratio (injector on-time) based on the signal
from the HO2S. This allows the air/fuel ratio to stay very close to 14.7:1.
Starting Mode
