High-Pressure Pump Timing: Why It Matters

Hello, I'm wondering why the high-pressure pump in a VW CR engine is also connected to the crankshaft and camshaft.

Shouldn't it actually not matter in which position the pump is? It only increases the pressure of the diesel fuel, which is then stored in the rail. The water pump isn't disconnected either.

So, can someone please enlighten me?
What have I misunderstood or misinterpreted here?

Thank you.

Ralf.

Hello Ralf,

The pressure in the high-pressure accumulator is not constant. I suspect that disconnecting the high-pressure pump is intended to better manage resonances in the fuel pressure.
The engine control unit can predict, based on a defined pump position, how the fuel pressure will change in advance.

Best regards, Rainer.

dieselschrauber wrote:

Hello Ralf, The pressure in the high-pressure accumulator is not constant. I suspect that disconnecting the high-pressure pump is intended to better manage resonances in the fuel pressure. The engine control unit can predict, based on a defined pump position, how the fuel pressure will change in advance. Best regards, Rainer

Absolutely correct!

Yes, that makes sense.

Thank you, I now understand.

The HD isn't a centrifugal pump. I hadn't thought of that.

Great.

Ralf.

Bosch describes the "injection synchronization" feature in the CP4 documents, which in the passenger car sector is typically a single-piston pump that does not provide continuous fuel delivery.

For comparison: CP1, CP1H, CP2, and CP3, as well as various high-pressure pump systems based on common rail technology (Deutz), provide continuous fuel delivery.

So, does it not matter how the pump relates to the rest of the system?

And what type of fuel pump is in my Passat 2.0 TDI (CBBB)?

Thank you.

Ralf.

Quote:

So, does it not matter how the pump relates to the rest?

Everything except the CP4 is actually irrelevant. Although, for example, with PSA, the high-pressure pump (CP3) is also disconnected, the synchronous operation is rendered unnecessary due to the 2/3 ratio.

Quote:

And what kind of fuel pump is in my Passat 2.0 TDI (CBBB)?

If it's a Bosch system, the EU5 standard typically uses a CP4 injector. This applies to most other manufacturers as well.

I suspect that one of the reasons the five-cylinder engine disappeared from the Crafter is that it would have been too complicated to adapt it. Instead, they could simply use a similarly powerful four-cylinder engine from the "passenger car/van" lineup.

Okay, thank you, so CP4.

Do other people also experience so many problems with chip-generating HD pumps?

"Mine got it recently too. It's quite an expensive thing."

Thank you, Ralf.


Subject: Off-Topic: Why don't I receive emails when something is posted here?

KombiBlue wrote:

Do all other people also have so many problems with HD pumps that produce shavings? Mine also experienced it recently as well.

It's quite an expensive ordeal.
What kind of engine do you have? What's the engine code?

Quote:

OT: Why don't I receive an email when something is posted here?

It should work, have you checked the spam folder?

Best regards, Rainer.

According to the signature, a CBBB.

Damn, I just thought that only the 3.0 TDIs of certain model years were affected.

@KombiBlue: What's the mileage and year of manufacture?

If it's the one from the signature... from 2009.

The mileage is still missing.