Originally Posted by
smokeshow
Your two primary knobs for transient fuel will be both of the 'Gas' tables under Impact Factor and Evap Factor. The impact table values represent the fraction of the fuel from a given injection event that will not enter the cylinder, but instead stay as a liquid in the head port. Baby steps with that one...since it is a fraction of a whole and not a detached quantity itself, adding a little too much can be way too much. The evap table represents a value proportional to the time constant of an exponential decay: it is continuously evaporating, unlike the impact factor where only a fixed amount of fuel hits the port wall. It isn't as sensitive, but good practice anyway to adjust these values little by little.
What you should be looking for on a throttle tip-in is an initial spike in the injector pulse width. The heavier the tip-in, the easier it is to see in the data. That spike is the extra amount of fuel that you have to add in advance to make sure the right amount makes it into the cylinder. If you don't have enough impact factor, the spike will show up as leanness in the wideband instead. Look at every one of your throttle tip-ins and you'll see exactly that. So you'll need to increase the value in that impact table where you are seeing the issue to account for the extra necessary fuel.
On the flip side, tip-outs will often show up as the opposite - a rich droop in the wideband. A quick decrease in manifold pressure basically sucks the fuel right off the port walls and ends up being more than you need. So the opposite must take place - give it less fuel on a tip-out. To do that, you'll still need to increase the values in that table, not decrease, since the evap factor essentially represents the rate of fuel vaporization. Keep in mind though that engines are imperfect and suffer from poor combustion during deep decel MAP/retarded spark advance maneuvers. Without a complete clean burn of the mixture, it can still show up on the wideband as leanness. And that is usually accompanied by the rich droop.
One caveat though, something I discovered when trying to get non-LSA injectors working in an LSA blower...you may run out of transient fuel before you fix the problem completely. The 'puddle' of fuel that the impact factor contributes to is clipped to 2 grams of fuel to prevent puddle models from getting too large. You can't monitor this value, but you'll know you hit that mass clip when adding more impact factor doesn't help anymore. That should be enough info to get you most of the way.