Montero LS 4WD V6-2972cc 3.0L SOHC 12 Valve (1994)
Air Flow Meter/Sensor: Oscilloscope Patterns and Waveforms
Wave Pattern Inspection Using an Analyzer 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 terminal (3) of the volume air flow sensor connector.
Note: Alternative method of connection (when test harness is not available): connect the analyzer special patterns pickup to ECM terminal (70).
Standard wave pattern
Wave pattern observation points: check that cycle time T becomes shorter and the frequency increases when the engine speed is increased.
Observation conditions: Engine idling at 700 rpm (Pattern changes with engine speed changes)
EXAMPLES OF ABNORMAL WAVE PATTERNS
Example 1
-
Cause of problem: malfunction of sensor interface
-
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.