aside from some cold start bugs, the engine starts and idles well at around 850rpm. we are setting up our secondary fuel injectors. we are using the staged injection option. we are using TPS based staging. staging turns on at 12, and off at 11 (throttle percents). the scaling factor is 255 (our secondaries are the same size as primaries). here's the weird bit:
when we enable staged injection, the engine has a hard time starting, and then when it does start it immediately dies. simply turning off staged injection eliminates the problem. when this failure occurs (with the throttle practically closed at startup), the secondaries are not receiving a signal (as they shouldn't yet) and obviously are not flowing any fuel (again, as they shouldn't). it seems like this is a software thing? simply enabling the staging screws up our cranking and makes it impossible to hold an idle for over 2 seconds. it can't be a wiring problem since the injectors are not even doing anything when this happens.
has anyone run into similar problems?
Thanks,
Max

 

after a little investigation it seems as though i should not be putting in "11" and "12" for the staging activation points. i want it to start staged injection at about 12% TPS (which is where the secondary plates start to open), but i guess i don't actually want to enter a value of "12" right? well apparently this value has to be between 0 and 255, so i figured that 255 equates to 100% TPS, so i did 12% of 255, which is about 31. i entered "31" where i used to have a "12", but i get the exact same problem. is there some non-linear transfer function to convert a 12% TPS to the correct value for the staged injection window?

 

First off, you need to calibrate your tps. closed tps will not mean it is at "0" when closed. Mine is right around 20 when closed and about 185 when open all the way. This is using an s5 tps with the full sweep part of it. You are assuming too much and its causing your engine to flood I assume. Staging should not be untill the higher rpms with some boost. Or in an n/a engine you can stage at a rpm at a certain kpa set point as an extra. You will need to do some more reading before you will figure this out I figure. Just keep monkeying with things till you figure it out. at least then you will know how it works a little better.

dpf22

 

yeah so we figured it out. we had three problems. we were not doing the ADC correctly, we were not interpreting Staging Off Delta correctly, and we did not have enough injections per cycle.

we ended up changing the staging point to 80, which CORRECTLY translates to a TPS of about 12 to 13 %

Delta off was changed to "2" because it's not the "TPS position to turn off" its really the "deviation (delta) from the ON point at which it turns off"

and the main thing that took some thinking (and this is the reason that it didn't even want to start) is because when you run staged injection it divided the number of injections per even in half regardless of whether it is actually activated or not. for this reason we were actually only getting 1 injection per cycle even though we had it set to "2" in "basic settings". because of this there were certain intake events that were not receiving any fuel because of fuel pulse "timing". we changed our "squirts per cycle" to "4", which resulted in 2 per cycle while staged injection was activated.
everything works finer now, i hope this helps others.

furthermore, why in the hell does everyone turn the secondaries ON at a certain RPM? they should come on when air starts to travel past them, hence when the secondary throttle plate begins to open. setting this to happen at x RPM might work alright, but it's certainly not the proper way to do it. the secondaries should only come on when the TPS is at a certain position (about 12% for our motor). am i missing something here?

 

Most people have an RPM component in the staging point b/c the stock ECU does.

I set mine on so that you have to be above a certain RPM AND above a certain MAP or throttle position.

I'm going to work on a code option for ms2/extra 2.5 that will internally calculate the primary duty, and stage whenever that duty is over a certain, user-selectable point.

That way you'll only use the secondaries when it's absolutely necessary, and when there is almost definitely enough air going by them.

Ken