Help with Staged Injection / Secondary Injection

[VSRacing]

Hi! I am trying to get staged injection / secondary injection to work, but have not been successful yet. The issue I am having is that the engine starts running too rich as soon as i am entering into the secondary injection split.

The setup is as illustrated in this diagram below. Four primary injectors are connected individually to the EMU Black. The secondary injectors are wired in pairs each to an injection driver pin. All injectors are the same cc/min size.

I am suspecting that I have misunderstood the staged injection parameters? I have interpreted the Secondary Injectors → Injectors size per output as the individual injector size, 245 cc/min.
Should Secondary Injectors → Injectors size per output instead be the total size of the injectors connected to each bank, i.e 2 * 245 = 490 cc/min?
What should I set Secondary Injectors → Num secondary injectors to?
Appreciate your feedback.

[Jadzwin_ECUMASTER]

@VSRacing

→ Injectors size per output instead be the total size of the injectors connected to each bank, i.e 2 * 245 = 490 cc/min?

You should enter 490cc/min. It is not enough clarified in the Help.
If still you will be too rich please publish the base map and the log and I will analyze it what could be the problem.

[VSRacing]

Thanks for confirmation and your help! Then I will test with 490 cc/min for the secondary injectors. Next track testing is next week hopefully. I will update with how it goes.

[VSRacing]

Update: The bike now runs good with the updated settings of 490 cc/min for the staged injectors

I can however not understand fully from the logs if it really is working correctly?

Looking at the log it seems like the injection events for the secondary injectors is a bit intermittent? It looks like it is sometimes injecting for a bit and then stops? I also expected the primary injectors 1-4 to have a much shorter inj time in the Inj outputs signal since the split is set to be 80 %.

I dont fully understand what the Injectors PW and Secondary Inj PW show during split injection.
I think that Secondary Inj PW show only the pulsewidth for each injection event for the secondary injectors, and there are two events per engine cycle for the sec injectors.
What does the Injectors PW show during split injection? Does it show the total injection time for both primary and sec injectors? Does it show only the primary injectors PW?

I am thinking about this setting Minimum inj. time and what it controls? If it as now is 2 ms, is it allowing sec fuel injection if the total sec inj fuel dose per engine cycle is >= 2 ms, or is it only allowing sec fuel injection if each one of the two injections events per engine cycle are >=2 ms?
I tried lowering it to 1 ms, but then the engine would run full lean when entering the sec inj split.

Assuming Minimum Inj time of 2 ms means that the sec injectors can activate if each sec inj pulse is >= 2 ms / 2 = 1 ms, it seems like the sec injection is at the limit for activation since the Secondary Inj PW in the logs are around 1 ms?
20250603_1851_Tisdagsträning_Linköping_Analyzed.emublog3 (391.2 KB)

[Jadzwin_ECUMASTER]

First of all the injection and axu outputs channel is logged at 25Hz.
So it is ok to check if some outpus are continously on, but it is not a good tool for such events like injection or other PWM stuff (too less frequency).

Split defines injectros flow splint not injection PW split. Both PW shows current PW of primary and seconday injectors.
Min PW means that secondary injectos PW must be higher to inject the fuel.

[VSRacing]

I think that I figured this out earlier last year and managed to work around the issue! I want to follow up here so that the issue hopefully can get resolved.

I came to the conclusion that the proper configuration for the secondary injection stage is to configure such that

Injectors size per output * Num secondary injectors equals the total flow rate of the secondary injection stage.

I.e in my case i have two pairs of 245 cc/min injectors connected to two individual injector driver outputs giving (2 x 245 cc/min) x 2 = 490 cc/min x 2 = 980 cc/min.

So I can enter

Injectors size per output = 490, Num secondary injectors = 2 OR
Injectors size per output = 245, Num secondary injectors = 4 OR
Injectors size per output = 980, Num secondary injectors = 1

it does not matter

Then after bench testing the ECU with signal generators simulating the crank and cam signal patterns and measuring with oscilloscope I came to the conclusion why the engine started running very rich as soon as the sec inj split is entered is that

The secondary injectors Minimum inj time settings is completely ignored.

What seems to be happening is that the fueling calculations are correctly performed and the inj split is correctly calculated taking the min inj time of the sec injectors into consideration.
However since the sec inj stage incorrectly output injection pulses already from 0 ms pulse width and not only for pulse widths above the secondary Minimum inj time setting a lot of additional fuel is added causing the engine to run super rich.

The results below illustrates this issue. Here I am running the ECU under steady state conditions at

Fixed 12000 RPM
Fixed 40 % TPS
Pri and sec inj dead times calibrated to zero

and only varying the commanded secondary injection split percentage.

Under these circumstances the fuel dosage delivered to the engine should be constant. I.e the total fuel flow from primary injectors + secondary injectors should be constant regardless of sec inj split percentage value.

0 % secondary injection split. Here it is working as expected with only the primary injectors operating.

20 % secondary injection split. Here the secondary injector stage is incorrectly activated at around 0.4 ms pulse width adding additional fuel causing the engine to run too rich.

40 % secondary injection split. The secondary injectors active below the configured 1.5 ms min inj time. The primary injectors pulse width does not change which is correct.

60 % secondary injection split. The engine now runs almost 60 % rich.

80 % secondary injection split. Now the pulse width for the secondary injectors are above the sec inj min inj time value of 1.5 ms and the primary injectors inject time is correctly reduced giving the correct fuel flow.

100 % secondary injection split. Only the secondary injectors are active. It works as expected and the correct fuel flow is delivered.

This table summarizes the results

I could work around this issue by setting the secondary min inj time to the lowest possible value of 0.5 ms and by tuning out the rich effect in the fuel table.

It also seems like the Fuel usage (l/h) measurement variable don’t take into consideration fuel flow from the secondary injection stage since it shows smaller values when sec inj split is active.

3.062 client and firmware.

EMU log is attached.

20260106_1932_Staged_secondary_inj_benchtest.emublog3 (156.4 KB)

[Greg]

Are you taking in consideration dead time of injectors i dont think you can add pw directly for example 50% sum of this pw will be longer because you have two injectros dead times

[VSRacing]

For this test I have set both the pri and sec injector dead times to zero to remove the influence of that.
But you are correct, if dead times are included the total pulse width of the two secondary pulses would be longer for the same fuel flow compared to if it is to be delivered by the primary injectors.

[Jadzwin_ECUMASTER]

Thnk you for your good job. It looks like the issue is exactly what you discover. I will fix it ASAP for you.

[VSRacing]

That is perfect thanks! Looking forward to coming releases with the fix .

[Jadzwin_ECUMASTER]

Here is a link to 3.062.001 with staged injection minimum pulse witdth bug fixed.

Dropbox

[VSRacing]

Thanks for very fast bugfix!

[VSRacing]

Tested new 3.062.01 firmware today and it works perfectly as expected!

20260110_1802_3_062_01_sec_inj_benchtest_fixed.emublog3 (65.4 KB)