Retarding the static timing is retarded, LOL.
But really, the top line is good.... so what if you can't inject ADTC in part load.
It's only the very start of injection, so why would anyone want injection to start AFTER TDC? Not even the stock map does this at high IQ.
BTW, see the stock SOI map where timing is ATDC? It is where the EGR map is used. No need for any ATDC, except for noise/NOx concerns.
I always thought that EGR retards combustion, but found out that in low loads it actually speeds it up (I guess the heat added?). So that makes sense now why they went ATDC.
Some stock SOI maps have bumps to 3-4 deg BTDC in the big ATDC area, right where fuel economy testing speeds are
(or so they say on ecuconnections).
Change nozzles, and you see the static timing changes (so its not going to inject sooner if you readjust the timing to the top line). That's not going to make you have bad timing up high where it's dangerous. It just makes the range from example 3ATDC to 18 btdc, to be able to be 3 to 24 . Still the tune is what calls for the timing, which sets the timing solenoid. The thing is, if that timing solenoid can't keep up - you lose timing, even though your range can go to 18 lets say, you may not get it when its requested. Like anything mechanical, there's "slack"
Following ecu connections, with some input by someone who did dyno testing (brum?). See where it used to be negative (ADTC) now it is slightly BTDC, don't need much timing because such little fuel is going in. As rpm climbs, timing goes up because of delay of combustion. As fueling goes up, timing goes up because of injection window being bigger.