E92A not using MAF values at idle when dynamic air is disabled

[Dominatorstang]

I notice when I disable dynamic air, that idle does not appear to use MAF values even though the scanner shows air calc as Hi Speed. I say this because I see a constant 18% rich mixture so I try cutting the values on the MAF, but it makes no difference to the 18% rich. I do see the new values in the scanner for MAF, but no change to idle air/fuel.

I am just overlooking something right?

maf idle tuning.hpl
maf idle I keep pulling values down but fuel error stays the same.hpl

[TriPinTaZ]

Based on those logs, you have some airflow and torque model issues. Dynamic air is never truly disabled. Your throttle blade shouldn't be open 15%+ with 0 degrees of timing at idle. It is likely exacerbating the issue.

[Dominatorstang]

I just keep learning more and more on especially 17+ models do not let you disable things. The thing is I actually get ~+15deg timing and ~15% throttle and ~20ftlb torque when I leave dynamic enable numbers normal. But I find -18% fuel trims being logged when coming to a stop and some pretty ugly fuel trims when coming out of DFCO which I read some of that on DFCO is normal. The rest of my fuel trims are pretty close, I am just trying to fine tune these areas.

[TriPinTaZ]

I just keep learning more and more on especially 17+ models do not let you disable things. The thing is I actually get ~+15deg timing and ~15% throttle and ~20ftlb torque when I leave dynamic enable numbers normal. But I find -18% fuel trims being logged when coming to a stop and some pretty ugly fuel trims when coming out of DFCO which I read some of that on DFCO is normal. The rest of my fuel trims are pretty close, I am just trying to fine tune these areas.

You can actually make DFCO kick in faster to negate that issue. I have to do that on some cars I tune. Its a very vague setting and I don't know why it has the affect it does, but it does.

Also, if you're getting positive timing with dynamic airflow "enabled" and negative with it "disabled" then you need to alter your VVE table in the idle area AND/OR modify your MAP Virtual Torque values. The VVE table is used at idle and transient but it all depends on what percentage the ECU weights towards VVE vs MAF. Idle and Transient has a higher weight towards VVE. WOT and steady state has a much higher weight towards MAF.

I suspect your fuel trims are partially to blame for your throttle blade being open 15%. I don't know the setup but that is high even for a cammed setup.

[Dominatorstang]

Thanks for the tips TriPinTaz. I will check into those.

[TriPinTaZ]

Thanks for the tips TriPinTaz. I will check into those.

I forgot to post this.

FUEL > OXYGEN SENSORS > LTFT IDLE CELLS THRESHOLDS > Change the Enable VSS and Disable VSS to speeds the car will never see. This will cause DFCO entry much quicker. I still think your fuel trims are out of whack partially because of the airflow or torque model keeping the throttle blade open too much.

[Shane Hewitt]

Just to rule something out, log your EVAP Purge. I stumbled on it by accident, wondering why the fuel trims at idle in my 18 Silverado would swing significantly. Some times trims would be as you would expect hovering around 0, other times I would see trims go into the negative high teens/low 20s............the fuel trim swings correlated exactly with when the truck was running EVAP purge events.

May be totally unrelated, but worth logging to rule it out.

[Dominatorstang]

You do make a great point with the EVAP. I would not think it should enable at idle, but if it were leaking then it could cause me some skewed numbers. I did unhook the hose and plug it for testing and add it to my log. It did not appear to be effecting me by leaking or opening at this time. Correcting the VVE at idle resolved my fuel trim issue. I now just ignore idle area when tuning MAF.

[GHuggins]

Keep in mind when you make changes to one table on these, you have to recheck and possibly tweak other tables. They all correspond with one another.