How to use fcar f3-d heavy duty tool solve Man Engine poor acceleration

Posted by fcar on September 30th, 2014

MAN Vehicle mode: MAN
Date of manufacture: June, 2000
Driving : 645201KM
Fault phenomenon: This vehicle dirving powerless, engine unable to accelerate, EDC light on.
Fault diagnosis: This vehicle is electronic control system, to diagnose with Fcar F3-D heavy duty scanner,connect testing cable to test head and main unit respectively,(diagnostic plug is above relay box besides center console).

Diagnostic socket
Pic.1 Diagnostic socket position

In the case of without 37-pin diagnostic connector,you can use jumper box to connect and diagnose.Jumper method see table 1,connect testing cable respectively with jumper box and main unit of F3-D heavy truck diagnostic tools.Turn ignition switch to ON gear position,swtich on power switch of Fcar heavy duty truck tools.Entry to menu 【Diesel】—【MAN】—【V5.3】—【BOSCH EDC MS5/M(S)5】—【Read DTC】,Fault display ”87 intake pressure sensor fault””85 coolant temperature sensor fault” 【Clear DTC】display“System clear success”in【Read DTC】“87 intake pressure sensor”“85 coolant temperature sensor”appear again,DTC cannot be cleared Selct menu【Read data stream】on menu and click to enter and check(Readout data see Table 2).To analyze the specific faulty part combining with data stream.

Name Jumper box jack label Diagnsotic socket label Diagnostic socket voltage V 
Positive VCC A 24V
Negative GND D 0V
Signal K 15 Z 23V
Signal L 7 a 23V

Table 1 Connection of Jumper box with diagnostic socket

Fault Analysis
Pic.1 Engine coolant temperature sensor

To analyze according to reading data stream, the vehicle engine still cold water temperature sensor data stream is 95 degrees, the intake pressure sensor data 120kPa. Start the engine, after idle for some time no change in water temperature data, depresses the accelerator pedal to increase engine speed, view the data stream, intake air pressure sensor data is still 120kpa unchanged, indicating that the water temperature sensor and intake air pressure sensor data is abnormal (see data stream of this vehicle in Table 2, Table 3 are data stream that has some changes), initially judge water temperature sensor and intake air pressure sensor part is defective.

Pic.2 Engine coolant temperature sensor

Check water temperature sensor and intake air pressure sensor, both of which were found abnormal, to be replaced.

Sensor name High speed Idle Static
Water temperature sensor° 95 95 95
Inlet pressure sensor kpa 120 120 120
Engine speed rpm 1900 730 0

Inlet pressure sensor position
Table 2 data stream of this vehicle

Sensor name High speed Idle Static
Water temperature sensor 85 85

Pic. 3 Inlet pressure sensor position
Inlet pressure sensor kpa 600 200 100
Engine speed rpm 1900 730 0

Table 3 changed data stream             

Replace water temperature sensor see Pic.2,inlet pressure sensor see Pic.3.Use menu on Fcar truck diagnostic tools menu to clear DTC,display clear success,Read DTC,system normal,road test,fault disappear,completely remove fault.

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