General Precautions of EFI System Maintenance
F-48
Related Malfunction Symptoms:
1. Idling Jitter
2. Weak Acceleration
3. Increased Fuel Consumption
4. Emission over Standard
Malfunction Diagnostic Guide:
Required Equipment: (Diagnostic Instrument with EOBD Diagnostic Function, Digital Multimeter, and
Correct Circuit Diagram)
Step I: Use diagnostic instrument to read the malfunction information
Read Result I Read Result II
MIL Lamp On P-CODE Present MIL Lamp Off P-CODE Present
P0304
P0304
Maintenance tips:
The malfunction has been confirmed, and the
following problems may possibly exist
1) Fuel injector needs to be cleaned (The 4 fuel
injectors to be cleaned at the same time)
2) Air intake passage needs to be cleaned
3 Air leakage with the valve of the 4
th
cylinder
4) Ignition system malfunction of the cylinder 4
th
(inspect ignition wire, spark plug and replace as
required)
5) Serious wear of the 4
th
cylinder
Maintenance tips:
The malfunction has not been finally confirmed.
Please wait for system confirmation.
60. P0321 BM Signal of DG (Rotational Speed Sensor) to Revolution Signal Gear Notch
Lost Frequently (Signal Malfunction of Rotational Speed Sensor）
Description about Malfunction Cause:
60-2 tooth speed test system is adopted, and the 60-2 inductive gear ring is installed on the flywheel to rotate
along with the flywheel (rotational speed consistent to crankshaft) so as to generate magnetic change in the
sensor, thus to generate induced AC voltage with its frequency based on the rotational speed. The signal
circuit of ECU transforms the input sine wave into square wave, and when ECU detects that the distance
between certain two square waves on the falling edge is larger than the spacing between the two teeth, the
reference position is immediately found. Physically this reference tooth pitch corresponds to the specific
position of the 1
st
cylinder, and the system internally defines the second falling edge behind the gear ring as
the software reference point signal (BM), and the angle of rotation for the crankshaft of the software reference
point away from the upper dead center of the 1
st
cylinder is a fixed value of 108°CA. Hence whenever the
crankshaft rotates for once circle, the system will receive a software reference point signal, and the position of
the system and the crankshaft maintain “synchronized” based on this software reference point signal, further
to ensure the control over correct fuel injection, intake, and ignition timing.
If any of the under-mentioned cases is found, it is then determined to be the malfunction of crankshaft
software reference signal (BM).
1. It is frequently found that the measured crankshaft software reference point signal (BM) is ahead or
behind the expected emerging position.
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