T5 Engine Jerking: CAAB Code Troubleshooting

Hi!

I have a T5 CAAB engine with a problem where the engine is not running properly. The compression is okay, and all four injectors and the high-pressure valve on the fuel injection pump have been replaced.

After 200 kilometers, the vehicle lost power again and experienced severe jolting at low speeds.

After resetting the learning values of the high-pressure pump, the vehicle is running smoothly again.

FSP P106500 Fuel pressure regulation - control differential.

Hi,

Please perform a complete vehicle scan. In principle, there are three possible reasons why the rail pressure is lower than what the engine control unit expects:
- Fuel system leak.
- Faulty high-pressure valve or faulty control system.
- The high-pressure pump is not pumping enough.

I would first check whether the pressure is generally too low or if it's simply not being regulated to the target value.
-> Compare the control of the high-pressure valve with the setpoint pressure, actual pressure, and motor speed.

Why did the workshop replace the injectors, and what is the vehicle's history?

Best regards, Rainer.

The vehicle has nearly 300,000 kilometers. It came with significant fluctuations in rail pressure. One injector showed an increased return flow, so it was replaced along with the High-Pressure Regulator (HDR) valve on the fuel pump.

The vehicle ran smoothly for approximately 500 km, but now it's experiencing jerking again. The other three injectors have since been replaced.

After the learning values of the high-pressure pump were reset again, the car ran for another 300 km without any problems.

Now it's shaking again, especially at low speeds and when going uphill, with no power.

After resetting the learning values in the pump again, it is working correctly now.

Compression exceeding 20 bar.
The pump delivers approximately 4 bar, as measured by the pressure gauge.
I checked the control valve N276 according to the instructions, and I was able to achieve a return flow of 100 ml within 30 seconds.
Difi NEW.

I've read that the pressure control valve on the fuel rail often fails, resulting in the P106500 fault code for "Fuel Pressure Control - Regulation Difference."

I am sending the AU scan now.

Quote:

The pump delivers approximately 4 bar, as measured by the pressure gauge.

It could be a pre-pump, but definitely not the high-pressure pump, because that would require a factor of 500.

Yes, the pre-charge pump reaches 4 bar.