Description

Sudden poor power and poor acceleration above certain rpm while driving could be caused by abnormal fuel system, intake and exhaust system leakage, abnormal EGR system, abnormal VGT system. The purpose of this inspection is to analyze the cause of poor power and poor acceleration.

Diagnostic Procedure
Current data inspection (Fuel system)
1.

IG S/W 'ON', ENGINE 'ON'.

2.

Connect scantool to Data Link Connector (DLC).

3.

Allow the engine to warm up to normal operating temperature.

4.

Electrical system and A/CON 'OFF'.

5.

Select 'Fuel pressure', 'Fuel pressure set point value', 'Engine speed', 'Actual injection Quantity', 'Pressure control valve(rail)', 'Output of Fuel Metering Unit(MPROP)' parameter on the scantool.

6.

Monitor 'Pressure control valve(rail)', 'Output of Fuel Metering Unit(MPROP)' at fuel temperature 50 ~ 70℃, engine speed idle rpm.

7.

Monitor that 'Fuel pressure' and 'Fuel pressure set point value' data should be almost same and 'Fuel pressure' data should be stable.

[ Normal data of fuel system ]

[ Stable 'Fuel pressure measured' data at idle. ]

8.

Use graph function after selecting 'Fuel pressure' and 'Fuel pressure set point value' parameters on the scantool.

9.

Monitor that 'Fuel pressure' and 'Fuel pressure set point value' data should be almost same at stall test.

note

Refer to 'Stall test' of detail inspections (Equipment settings).

[ Normal 'Fuel pressure' data ]

Symptom

Inspection procedure

Case1

● Fuel system data are normal and "Fuel pressure" is controlled well by ECM to follow "Fuel pressure set point value".

● Go to 'EGR and MAFS inspection'

Case2

● 'Fuel pressure' is unstable or 'Pressure control valve(rail)' and 'Output of Fuel Metering Unit(MPROP)' data are abnormal.

● 'Fuel pressure' is NOT controlled by ECM to follow

● 'Fuel pressure set point value' at stall test, finally poor acceleration occurs or engine stall.

● Go to 'Low fuel pressure inspection'

Яндекс.Метрика