VP37: Spritz Valve and Pump Internal Pressure

First of all: I did it - I bought the Bosch Diesel Engine Management (and I'm now learning it by heart 45 EUR, it's worth it)


Regarding the VP37 fuel injector adjuster, as stated on page 231, the fuel injector adjuster solenoid controls the internal pressure of the pump.
open valve -> pressure reduction (at the actuator side) -> subsequent spraying start
geschlossenes -> Voller Druck auf Versteller -> früher

So, if the pump is starting too early, but the PWM of the solenoid valve is already at its maximum, and furthermore, the basic setting of the pump is exactly on the midpoint, then I have:

1. a contradiction
2. This has absolutely nothing to do with the "insufficient pump pressure due to wear" mentioned earlier, because that can only occur "too late".

I see the contradiction as follows: How can the optimum be achieved in principle, when almost 4 degrees are sprayed off in normal operation?!?!? (Idle, Target -3.1° -- ACTUAL 0.6° -- PWM at 3.1% therefore open = late)
Especially, how can "PWM on start" change if I go to the basic settings (the motor noise and speed change)?

Could "leaky" valves also be a reason - opening too early, for example?

In the recently tested ASV, there was a noise issue at idle and during acceleration. NIX changed.


I don't want to create problems - I just want to understand the system.

m;

Hello dieselmartin,

I am still in the process of fully understanding the complexities of diesel engine management,
However, it can definitely be said that a correctly set initial spray start, in the basic settings for new nozzles, causes a shift in the spray start towards earlier timing compared to old nozzles. This is because the 170 bar (wear limit) opening pressure is likely to be reached sooner in time than the 190 bar. How significant this shift can be, our professional mechanics should know.

Hi, KAi

@ Kai

I understand.

But I haven't exchanged anything yet!!!

I have only been measuring so far and have already found inconsistencies

m;

dieselmartin wrote:

The contradiction I see is: How can the optimum be achieved in principle, if almost 4 degrees are sprayed off course in normal operation?!? (Idle, Target -3.1° -- ACTUAL 0.6° -- PWM at 3.1% therefore open end = late) Especially, how can "PWM on start" change something if I go to the basic settings (which changes the motor noise and speed)?

Hi Martin,

If there is a noticeable difference between the operating settings and the default settings, the pump must also be operated differently - that's what my logic tells me.

It seems (I haven't measured it!) that the PWM of 3.1% is set to 0% as the default setting in normal operation, so that the valve receives a constant voltage without timing, which, (presumably!) causes the metering valve to move a little further than in normal operation.

As I said, purely theoretical, but I can't think of anything better...