10 Cent Injector Start/Adjustment Range (VP37)

Hello everyone!

'In the 10-cent tuning process, the possibility of advancing the fuel injection timing is also considered.'
Delaying the needle advance signal using an RC circuit is mentioned.

It is recommended to use a 470 ohm resistor and a 100 nF capacitor there.

Since I couldn't find any more specific information using the search function, here are my questions:

1.: Has anyone already measured how many kilowatt-seconds an earlier injection timing actually results in, in practice (of course, at a specific RPM and with the injection timing not yet limited)?

2.: What is the actual adjustment range (in kW degrees) of the injection timing adjustment (full <-> no injection at all, with the same amount of fuel injected) on the VP37?

Thank you in advance!

Best regards to everyone.
Michl.

MichlM wrote:

Hello everyone! It is recommended to use a 470 ohm resistor and a 100 nF capacitor there. 1.: Has anyone measured how many kilowatt-grades an earlier injection timing actually results in, in practice (of course, at a specific RPM and with the injection timing not yet limited)?

Hi Michl,

A true measurement (via the diagnostic port) is practically impossible because the engine control unit, with the NHG manipulation, essentially outputs the same target and actual values as it would in a normal state.

I once tried to infer the effect on [something] based on the still different key ratio (with/without NHG distortion).

For this, I took a third run with an SB (presumably referring to a specific device or system) that had been adjusted by 2 degrees earlier.
The pulse width matched the NHG distortion between 3000 and 4000 rpm to such an extent that I can say that approximately the approximately 2° advance I had calculated was achieved.

Quote:

2.: What is the actual adjustment range (in kW degrees) of the injection timing adjustment (fully activated <-> completely deactivated injection control - with the same amount of fuel injected) on the VP37, anyway?

During the fuel cut-off phase after the DZR test, the target injection start time shifts by approximately 18° KW towards a later timing at around 4000 rpm.
However, since the actual value displayed during deployment (with thrust shut off) is always 0°, I can only speculate that the real steering control range must cover at least these 18°.

The adjustment range will likely be much narrower at low engine speeds, because there isn't a high pump pressure inside the injection pump that can be "overridden" by the fuel injection timing adjuster to allow for late injection and improved scavenging.

2.: What is the actual adjustment range (in kW degrees) of the injection timing adjustment (full injection <-> no injection at all - with the same amount of fuel injected) on a VP37 pump?


The VP37-EDC should be calibrated to 15° northwest, which translates to 30° clockwise when considering the four-stroke engine's timing.

CU Gremlin.

Thank you very much for your prompt information!

Now I am (hopefully ) up to speed...


Best regards!

Michl.

Deleted upon request.

Therefore, it's not so easy to simply double the adjustment angle for the motor. The 'truth' lies somewhere between Ulf's 18° and Gremlin's 30°. But anyway, does it really matter for manipulating the injection start timing?


Sure... and it's also quite obvious that the 30-degree adjustment range on the motor doesn't really serve a purpose.


Detail on the periphery: In cases where a reference mark for the OT (optical transmission) is incorrect for any reason in a VP15/VP34/VP36/VP37 system, the operating data from the control unit may be correct, but the motor runs unsatisfactorily. In the last 8 years, I have encountered 3 such cases with motors that have a distributor pump. I personally analyzed 2 of them. The third came from a forum and was very specific and easy to understand. There's really nothing you won't find.

It's only logical. The pump receives a speed-boost adjustment (SB) due to the internal pressure. In other words, with the control valve closed, the SB is solely dependent on the internal pressure (which equals the speed). The EDC system knows this curve and takes it into account in its control loop. If the pump is twisted relative to the engine, but still within the adjustment range, this characteristic curve is distorted. The control loop then has a problem and will work unsatisfactorily, especially with significant dynamic changes.

CU Gremlin.

diesel.gustav wrote:

In cases where a false reference mark is used for the OT (Optical Torque) due to any reason, the operating data from the control unit may be correct, but the engine runs unsatisfactorily. In the last 8 years, I have encountered 3 such cases with engines equipped with a distributor pump on VP15/VP34/VP36/VP37 systems. I personally analyzed 2 of them. The third case came from a forum and was very specific and easy to understand. There's really nothing that doesn't exist.

Hello Gustav,

How can something like that happen?
Misaligned output shaft sensor wheel, or a faulty output shaft sensor?
What were the causes in "your cases"?
What was the size of each error in degrees?