Problem:Poor acceleration occurred and the maximum speed was only 2000rpm

 

First of all,we checked the truck information with its owner.Its injection pump and nozzle were already checked and everything is ok.The howo nozzle has been replaced while problem still there.

 

Analyze:

First, the engine fault detection is carried out with the special diagnostic instrument for this diesel engine, and the following fault codes are found:

1.P1266 No load on feed pump 

2.P0193 Common rail pressure sensor signal is too high

3.P0191 Common rail pressure sensor signal constant value

4.P0093 Supply pump lost load due to leakage from hand pump

5.P0502 Speed sensor signal frequency short circuit or open circuit

 

After clearing the above fault code, start the engine again, read the engine fault code, found no fault code display.Read the dynamic data flow of its engine as follows:

Accelerator pedal position sensor 1 output voltage 0.74V

Acceleration pedal position sensor 2 has an output voltage of 0.37v

Target common rail pressure 62Mpa

Actual common rail pressure of 48.48Mpa

Pressure is 114Kpa

The output voltage of the intake manifold pressure sensor is 1.21V

The maximum speed after the throttle is pressed is 2000Rpm, and the target rail pressure is 135Mpa. However, the actual rail pressure is only about 80Mpa. Obviously, the rail pressure is not enough, causing the engine to be unable to add oil.Considering that the oil pump nozzle has been overhauled and the problem might not come from here, we pulled out the tubing joint of the pressure limiting valve on the common rail pipe and found that the pressure limiting valve had a large fuel flow when idling.It can then be judged that the pressure-limiting valve has been damaged.

 

Troubleshooting & Solution: after replacing the pressure limiting valve, the data flow was read again and found that the voltage value of the rail pressure sensor would drift, so a new rail pressure sensor was replaced.Test again, and read the dynamic data flow, no more trouble.Finally the problem is completely solved.