diesel tuning anti Lag/ "prespool" techniques

hello, I have reverse engineered Isuzu (and some other Makes) denso sh70xx ecu's far enough to make custom code with custom maps.

currently I have an os patch, that when I press the brake pedal and the cruise + button I enter "prespool" mode. it activates a 12x12 table with RPM and Inj Quantity as the axis' the outcome of this map is then used in My "main SOI" function in order to retard timing at 1500RPMS until the brake is released. I also have a 2d table that is limiting IQ while I am in "pre spool mode" this is to manage egts. At Cut, I am getting misfire(white smoke) rather then black smoke/flames/turbo spool. I think this is likely due to the amount of time between Pilot injection, and main injection. I am debating whether I should ad maps to also retard pilot injection, and lower rail pressure.... or! I also found a post injection function in the ecu that was never enabled by the OEM. I am considering enabling post injection during this "pre Spool Mode". I am in no way a professional at this nor am I a diesel tuner. I just have a lot of time on my hands. hoping to glean some input from someone that may have experience tuning standalone diesels. what are the maps you like to see in a prespool tune? can this be achieved with two injection events or are three better? I imagine that this function will also later be employed for antiLag

I don't have any real world experience to offer, but how much have you retarded SOI? and how much have you limited your fuel qty? Can you start with just loading it up with no prespool maps changed (just stall it up without holding your cruise + button in your case specifically), get a baseline for how much boost you can generate and what RPM it gets to.

Then try again with only minimal changes, say retard main SOI by 10 deg and leave the IQ as is, or maybe even increase your max qty 5-10%, see what effect this has.

I think you may be fighting yourself in this instance if you are trying to control EGT's during a spoolup strategy, those things are almost at odds with each other. You need heat to spool the turbo in absence of mass flow.

Sounds like a really cool project, interested to see where it goes. How did you even go about writing custom code for it? It's always been something that interested me but I've not been able to find any good resources on the topic and wouldn't even know where to start.. are you using IDA pro, Ghidra or similar?

Diesels are different from petrol/gasoline engines, so you can't directly compare them.

Following on from Ben's comment, it also needs heat for the fuel to ignite - if the fuel is being introduced on the back side of TDC, the air may not be hot enough to ignite the fuel properly?

NOTE, I'm not a "diesel guy", but if you have a pre-injection option, this should potentially prove useful to increase the charge air temperature to improve combustion - maybe move it nearer to TDC?

One thing to watch out for is SOME piston bowl designs are sensitive to injection timing - this may not be an issue with that engine, but something to bear in mind.

Awesome work you have done on that ecu, can you share with me a mapack and your file to check it? i have not played with Sh7058, only bosch ecus and im very curious to find how it works too.

You are right you have to keep dwell time between pilot and main the same "ish", pressure, temp and rail preasssure impacts on how much you need to retard pilot, in some cases you retard too much main injection and that produces a more difussive combustion "like a torch from the injector" and you need to advance it a little...

Overall to get a boost control like antilag or launch control.

Reduce rail pressure (combustion happens slower and increase ignition delay so it happens latter on the stroke)

Reduce Main injection and pilot injection by one deegre at time.

DONT Reduce main injection to like -15 (deegres) you will be injecting outside the bowl of the piston

Try increasing fuel q on pilot injection q after finding the optimum retard of timing of main and pilot injection.

Be aware that this is general guideline as RPM range and boost pressure will afect it enourmous by varying the ignition delay in the cylinders.