Optimize Consumption: Injection Start Optimization

Hello.

In almost all modern diesel engines, the start of injection is shifted later than the optimal point for torque, especially under partial load conditions, due to exhaust emissions and noise. Therefore, there is still significant potential for fuel consumption reduction by advancing the start of injection.
In the high-load range, there is likely a risk that further premature adjustment of the injection start time could generate harmful peak pressures.

Therefore, I have chosen the following approach:
"Regarding adaptation channel 4, I've generally adjusted the injection start time to be earlier. I've mechanically adjusted the ESP (Electronic Stability Program) so that the timing is still within the tolerances, but slightly delayed. This allows the injection start time control to reach its mechanical limit at full load. As a result, the original full-load injection start time is only slightly adjusted towards being earlier."

What do you think of this approach?

How many degrees can you safely adjust the ignition timing advance? Approximately where is the optimal fuel consumption point?

I found something similar on this topic in another forum:
http://fatty-fuels.ubitco.de/messages/21793.html

It's adjusted by approximately 5-6 degrees towards an earlier time.

Comments, criticism, and suggestions for improvement are welcome.


Best regards, Joachim.


Volkswagen Bora, 110 horsepower, ASV engine, model year 2002.

Hi,

I'm afraid this probably won't work out well, because the engine control unit will eventually detect the excessively large difference between the desired and actual injection start timing when driving at full throttle. This will definitely result in at least one error message, and very likely also a limp-home mode. And that will happen when you're driving at full throttle and high RPMs, for example, when overtaking.
I find that quite unfavorable.

In Uli's post on the Fatty forum, only the fuel injection map was modified, specifically to inject fuel earlier in the partial load range.

Regarding fuel savings with a faulty AGR valve and a "good" spray start timing, I can only provide a rough estimate, which depends heavily on the driving profile: approximately 0.5 liters per 100 kilometers. The higher the proportion of partial load in the driving profile, the greater the potential fuel savings.

For the sake of completeness: such modifications are not permitted for use on public roads, and the vehicle's operating permit will be invalidated.

Best regards, Rainer.