fcar

http://www.automobilediagnosticscanner.es
Model: Isuzu
Year: 2007
Electric Control System：Euro III Engine
Fault Phenomenon: the malfunction indicator of the car does not light up. We learned from owner that when the car is running at the speed of 50 km/hour, its engine becomes powerless; in idle state, the engine could be throttle up normally, it could not be throttle up while driving at high speed, if throttle up engine urgently, engine would rush forward, along with the increases of fuel consumption.

Fault diagnosis: the car was equipped with EFI system, according to the judgment, it is might be the electric control system that cause the failure, first of all, use Fcar scanner to read fault code, connect scanner, then enter Asia, choose "Isuzu” according to the model, choose the engine type to enter into the corresponding system to read fault code. The decoder shows that: "P1520 air inlet manifold impeller failure; parking/neutral position switch short-circuit badness".

Failure analysis: malfunction parts could not be located just with the fault code that read, analysis must be made on the basis of data stream and fault code, after using decoder to read data stream, the engine data stream is in (table 1). Step on the accelerator pedal and check data stream, we find that when the engine speed rises, the actual air flow is changing between 715 mg/str to 821 mg/st , By comparing with the Isuzu standard data stream we know that "actual air flow" is abnormal (see table 2). Theoretically, the increasing of engine speed and the volume of inlet flow rises with the increasing of engine speed. When the engine running at 1500 turns, the actual value of air flow should reach 1200 mg/st or so. However, when the engine running at 2000 turns, data stream still shows that the actual air flow 821 mg/st. The initial judgment is the intake system might be faulty. Adhering to the principle of handling easy one before the difficult one, check the air flow sensor first. Through the inspection, we found the air flow meter has been damaged.

Troubleshooting: clear fault code out after replacing air flow meter, then read fault code out again, auto scanner displays: "system normal". Through road test we found the failure phenomenon has disappeared, at this time we affirmed that the malfunction had been eliminated.

Tabla 1 Los flujos de datos que se ha leído

Name of the Data stream

High Speed

Idle Speed

Stationary

Table2 estándar Valor de la corriente de datos de Isuzu

High Speed	High Speed	Idle Speed	Stationary
Engine Speed RPM	1500	701
Vehicle Speed Km/h		0
Pump Speed RPM	432	349
Accelerator Pedal Position %	50.00	0.00	0.00
Actual Air Flow mg/stroke	1200	800
Rated Air Flow mg/stroke	1006	1006	1006
Atmospheric Pressure kPa	100	100	100
Rated Fuel Injection Quantity mg/strk	18.0	14.4
Actual Injection Quantity mg/strk	18.8	15.1
Rated Injection Starting Angle℃A	11	8.8
The Actual Injection Starting Angle℃A	11	8.7
Coolant Temperature℃	60.0	46.5	26.0
Fuel Temperature℃	38.2	35.4	28.0
Inlet Temperature℃	33.0	31.9	26.0
System Voltage V	14	14	12