FUEL SYSTEM <4D5-step
III
> -
Troubleshooting
13-54
Standard wave pattern
(V)
ATDC
90
_
1 engine revolution
BTDC35
_
Crank angle
sensor output
wave pattern
TDC
TDC
5
0
BTDC9
_
ATDC
12
_
T
Explanation of Wave Pattern
The crank angle sensor detects the rotation of a sensing plate. Accordingly, the period T (seconds) can
be measured and the engine speed can be calculated from the following formula.
Engine speed (r/min) =
2
4T (sec)
×
60 =
30
T (sec)
Wave Pattern Observation Points
Check that cycle time T becomes shorter and the frequency increases when the engine speed is increased.
Examples of Abnormal Wave Patterns
D
Example 1
Cause of problem
Sensor interface malfunction
Wave pattern characteristics
Rectangular wave pattern is output even when the engine
is not started.
D
Example 2
Cause of problem
Abnormality in sensor disk
Wave pattern characteristics
Wave pattern is displaced to the left or right.