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.
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HOMESERVICE MANUALSMITSUBISHI2004DIAMANTE V6-3.5L SOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSAIR FLOW METER/SENSORTESTING AND INSPECTION
2004 Mitsubishi Diamante V6-3.5L SOHC
Air Flow Meter/Sensor: Testing and Inspection
2004 Mitsubishi Diamante V6-3.5L SOHCSECTION Testing and Inspection
VOLUME AIR FLOW SENSOR
Measurement Method
1. Disconnect the volume air flow sensor connector, and connect the special tool (test harness: MB991348) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to volume air flow sensor connector terminal 3.
Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to PCM terminal 65.
Standard Wave Pattern
Wave Pattern Observation Points
Check to be sure that cycle time T becomes shorter and the frequency increases when the engine speed is increased.
Examples of Abnormal Wave Patterns
- Example 1
CAUSE OF PROBLEM
Sensor interface malfunction
WAVE PATTERN CHARACTERISTICS
Rectangular wave pattern is output even when the engine is not started.
- Example 2
CAUSE OF PROBLEM
Damaged rectifier or vortex generation column
WAVE PATTERN CHARACTERISTICS
Unstable wave pattern with non-uniform frequency. However, when an ignition leak occurs during acceleration, the wave pattern will be distorted temporarily, even if the volume air flow sensor is normal.
Measurement Method
1. Disconnect the volume air flow sensor connector, and connect the special tool (test harness: MB991348) in between. (All terminals should be connected.)
2. Connect the analyzer special patterns pickup to volume air flow sensor connector terminal 3.
Alternate method (Test harness not available)
1. Connect the analyzer special patterns pickup to PCM terminal 65.
Standard Wave Pattern
Wave Pattern Observation Points
Check to be sure that cycle time T becomes shorter and the frequency increases when the engine speed is increased.
Examples of Abnormal Wave Patterns
- Example 1
CAUSE OF PROBLEM
Sensor interface malfunction
WAVE PATTERN CHARACTERISTICS
Rectangular wave pattern is output even when the engine is not started.
- Example 2
CAUSE OF PROBLEM
Damaged rectifier or vortex generation column
WAVE PATTERN CHARACTERISTICS
Unstable wave pattern with non-uniform frequency. However, when an ignition leak occurs during acceleration, the wave pattern will be distorted temporarily, even if the volume air flow sensor is normal.
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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.