TT_Vert

iTrader: (12)

or doing something else? Im trying to understand exactly what is happening. And lets say the LTFT is -2 and the STFT is -0.8. Does this mean the actually correction at that time is the LTFT of -2 PLUS the STFT of -0.8? or just -0.8?

Thanks
dave

66ImpalaLT1

Doesnt change the IFR TABLE at all, it changes the resulting injector pulse width.

My understanding, which may be incorrect, is that the LTFT of -2 contributes to the injector pulse width. I also think that if the STFT stays consistantly around -0.8 for a period of time it will move the LTFT closer to -2.8 not closer to -0.8.

You might be overthinking it a bit, but there's nothing wrong with that. The whole point of LTFT tuning is to get your WOT to perform consistantly. Since negative LTFT doesnt affect WOT, but positive does, we try to keep them negative for consistancy.

TT_Vert

iTrader: (12)

ok im just trying to understand what exactly is happening so in the future i can play w/ it with more complex setups.

dave

TT_Vert

iTrader: (12)

ok so, lets say my LTFT is at -4 and my STFT is at 0. Does this mean the STFT is exactly what the LTFT says it should be or is it actually 0? :


Dave

jimmyblue

iTrader: (11)

You have a fuel shot calculation that is based on the
desired AFR, MAF (and/or VE, MAP, RPM) airflow and
the injector table. That's the open-loop fuel calc.

Then it's multiplied by 0.96 (for 100% + (-4% LTFT) +
(0% STFT) as a fine adaptive adjust, that's how the
loop is closed.

TT_Vert

iTrader: (12)

ok is the adjustment from the LTFT plus the STFTs modify the IFR or what?
IE 4% less in IFR table?

So to ensure im understanding this correctly. if i had a LTFT of -4.8 and a STFT of -5.2 id have an overall correction of -10%/
Dave

jimmyblue

iTrader: (11)

The IFR table is static data. The open-loop part of the
calculation only changes via programming and sensor
inputs. The trims modify the primary calculation's result,
downstream - not its bedrock data.

As to the second example, I believe you have it correct.
Though whether it's really 1.00-0.048-0.052 = 0.900X,
or (1.000-0.048)*(1.000-0.052)=0.902X, I don't have
the detailed algorithmic knowledge to split gnats' gnuts
that finely.

TT_Vert

iTrader: (12)

lol ok so i guess im still confused do you know how consistantly the STFTs would have to be in a certain area before they begin to affect the LTFT and bring the Strims back to 0??

Dave