I'm coming from a week reading deeply about Bosch Motronic... so I know how that handles Load and its definition is this:
Motronic needs exactly three things to calculate LOAD.
1) A signal from the air meter, normalized to "Q" airflow in kg/hr
2) A measure of current engine rpm "n"
3) A programmed injector size constant "Ki" (K sub eye)
LOAD aka Tl (Tee sub ell) is calculated as:
Tl = Q / (n * Ki)
LOAD is not just a representation of cylinder filling, but the
theoretical Injector Time Open (Ti, Tee sub eye) needed to reach
stoich (Lambda= 1) with the current injector setup assuming that
the motor is "perfect".
Which it isn't, hence there are fueling tables which are used as
multiplicative corrections to LOAD to reach the actual Ti.
Hope this clarifies.
Well, here's the math if you have a MAF that produces an analog voltage as
a function of the airmass
First find Q ...
Q=f(Up/Uv) where Up/Uv is the ratio of the MAF output to reference voltages
(Bosch meters are logarithmic/exponential)
From Q, the speed of the engine (n, in rpms) and a CONSTANT (Ki)
which quantifies the fuel injector flow rate we can calculate
the LOAD SIGNAL (Tl) which is effectively the THEORETICAL (Lambda=1)
injector open time for the currently inducted amount of air
per engine cycle or stroke (depending on whether we have a
batch, semi-sequential, or sequential EFI system).
Tl = Q / (n * Ki)
With Tl quantified, we now take into account the vagarities
of the particular engine family and operating conditions by
introducing multiplicative factors to correct the theoretical
injector time to the ACTUAL time for injection (Ti) needed
at that instant. Finally an ADDITIVE factor (Tv) is added to
compensate for the differing injector opening time under lower
than nominal voltages.
Ti = (Tl * [C,D,E...]) + Tv
It is this signal (Ti) that is applied to the injectors
Hope this helps, it's from a BOSCH primer I'm writing ...
So now I have some confusion about how MS3 handle MAF and what Load really is in MS3 maps.
--- I need to know what I have to do to use MAF in ms3. and maybe to resume all info in one topic, since it's all scattered and there aren't deep docs in MS3 manual
1) I know I need a MAF transfer function. I have it, it's 0-5v in kg/h. I'll convert it to adc counts and upload it with tunerstudio. Plenty of docs about this
2) I set in TS:
control algorythm -- MAF
secondary fuel load - disabled
multiply MAP -- don't multiply
incorporate AFRtarget don't include AFRtarget ????? this is ok?
primary ignition load -- MAFMAP
secondary ignition load -- disabled.
AFR table load -- use primary load (algorithm)
EAE table load -- use primary load (algorithm)
3) what I should do with VE table? (engine ran until now in SD, so they are all tuned by MAP)... bosch motronic uses fuel maps as "
multiplicative corrections to LOAD to reach the actual Ti(injector time open)". MS3 manual says that when using MAF as control algorythm VE tables are not used. So I could leave them as they are(SD tuned values)?
4) If I tune with 19# injectors in MS3, then I swap 42lbs injectors, following motronic logic I should change Reqfuel and inj dead-time, small pulsewidths and I should be ready to drive in minutes and near perfect tune... It's right with MS3 too?
5) Maf correction table... what's its use if I already have a perfect maf transfer function? nothing, right?
6) I'm speaking MS3 vs motronic because I have all maps from motronic that I may be able to use with some conversion, fuel, ignition, WUE, ASE, something like EAE etc. and it would be nice to be able to use in some way some of them.
as you can see I have some confusion about tuning with MAF and MS3...