Something missing in transient fuel

[Maxwell Power]

I'm trying to get tip in to not fall so lean and the available tables just aren't cutting it. Lots of other calibrations have more available for transient fuel so I'm certain something is missing.

These tables are factors of an existing value.

Where is that value? Just based off the VE table?

Any help would be greatly appreciated.

The picture shows this, but:
The car in question is 05 CTS-V with 5.7
The engine is now a 6.3L with a cam and maggie setup.

Now that the temp has dropped my tip in stumble is even worse. Logs show it is falling very lean, very instantly on a quick stab.

[Ethan_Bill_Bennett]

Just my two cents, I have been working on and learning my idle for quite some time now and I spent hours and hours dialing in air flow and IAC tables to get it to idle right, go into gear right, and be good on tip in. I solved most of the issues but I still didn't have alot of torque in drive, reverse, and on tip in. The idle would dip down, stumble, and I would oscillate between rich and lean. I found that if I matched up the idle spark advance tables to the main spark advance table so that there was a smooth transition on tip in, I had plenty of torque. I also went to a more aggressive cam before I started tuning and I wasn't aware that I needed 6 more degrees of advance to make a stable idle lol. Everything is pretty rock solid now. I also changed the power enrich rate from 1.0 to 1.25 because I was logging a KR on WOT transients. So it could be in your spark advance, since you have a new cam, or in rate of power enrich... or I could be way off lol.

[JamesLinder]

I would try increasing throttle cracker air in the area you are experiencing the stumble. As I understand it, TC air is supposed to add the extra air (and fuel) the motor needs when you open up the throttle and there is a sudden rush of additional
air flow. This is also where VE table values are used the most, and having VE values
to low would also contribute to being lean on throttle transitions. You might want to post your current tune so I can look at the values you have in your tables.

[Maxwell Power]

Thanks guys.

I just figured it out this morning. "Minimum Fuel Milligrams"

Not actually what it's for it seems, or not explained properly and likely the wrong units.

The way it seems to work:
Seems that it should be a unit of time based on injector pulse width which could be mistaken for a fuel measurement. However, since it isn't a fuel measurement and it is a unit of time, when you add bigger injectors this throws it off.

1. Engine calculates continuously the amount of air entering the engine.
2. That calculation is never very smooth as the system is very dynamic.
3. When there is a change in rate and the ecu is calculating transient fuel there are thresholds that much be exceeded for it to actually inject extra fuel. I'm guessing this is done to help with gas mileage and keep the engine from developing any surges. So when the airflow changes at a quick enough rate, the calculated fuel needed changes. The calculation must exceed this threshold for accell fuel to be injected.
When installing bigger injector the pulse width needed for the same quantity of fuel drops dramatically. This means that this threshold is now much too high for the ecu to begin it's accel fueling strategy on time resulting in a lean spike at tip in.

Again, that's just how I see it and how it fixed my issue. I just lowered that value by the same ratio as my injector increase and the car instantly ran better with excellent throttle response and no more lean tip in.

Maybe the "pros" can come in here and verify.

[propliner]

What number are you now using for Minumum Fuel Milligrams?

[Maxwell Power]

What number are you now using for Minumum Fuel Milligrams?

right now just .020.
I'm not done. I still have to get her back in the dyno and get the wbo2 plugged into it to follow the afrs during a tip in transient.
I just know that dropping this made all the difference in the world. When I get on the dyno, I'll change it and see where it takes me.