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Testing Sensors
Section
2
FLOW
- F +
Typical
MAF
Sensor
• Related trouble codes sent by computer.
• Driveability problems such as hard starting,
rough idle, stalling, hesitation, stumble, surging,
knocking (pinging), poor fuel economy, black
exhaust smoke, backfiring, catalytic converter
overheating or no torque converter lock-up.
When to Test
Location
The sensor is mounted in the engine incoming air
ducts—typically just behind the air cleaner assem-
bly or near the throttle body.
How it is
used?
The computer needs to know incoming air flow to
properly adjust air/fuel mixture and ignition timing
for varying engine load and operating conditions.
What is It?
This sensor is an electronic module which sends a
signal to the computer indicating the amount of air
entering the engine. Depending upon sensor type,
the signal may be a dc voltage or a frequency. The
signal level increases (higher voltage or frequency)
as the air flow increases.
Within the sensor is a heated wire located in the
path of incoming air. The module determines air
flow by measuring the temperature drop of the
heated wire as air passes around it.
Mass Air Flow (MAF) Sensors
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