More questions:

Doesn't the intake calibration determine the load since it determines the mass air flowing into the engine?

Is there any other factors that play into load determination in the stock ecu besides the intake calibration?

 

Well, it finally got pretty cold here in the deep south last night and I noticed that I was hitting 9.5:1 at WOT. At first I thought that I had not reloaded my realtime intake calibration correctly and that was why it was running extremely rich. After reloading and double checking from logs whether or not the realtime map was actually in use I determined that it was in use and that that wasn't my issue.

I then started looking at IAT and it was in the low 60's last night (ambient temp was close to freezing). I also noticed that I was hitting loads of 4.0 when previously I was maxed out at ~3.3.

Upon consulting him, SS thought that my load scaling was causing me to run rich as it would have interpolated farther out than my max load column (3.4 from Wolf's rescaled base map).

well, INTERpolation means that you have available data further out than your operating point. if your maps don't have available data out PAST that load value, then the ecu was EXTRApolating.

in this case, the target afr is what you see in the closest load with valid data. it cannot (and should not) assume that you want anything other than what you tell it. so if your map afr target was say 11:1 in your higest load column, and you were actually hitting 9:1, then i would have to infer that the upper end of your MAFv-->g/s translation table is off.

however there MAY be other maps that are coming into play to offset your afr target. for example on my bugeye rex ecu there is an additional lambda offset map called "load/rpm target bias manual" which is a 7r/8c matrix. mine was NOT zeroed out in oem form (though it is now). i would not be surprised if your more complicated 32bit ecu has similar correction maps applied to it.

until you determine if there are other corrections applied you can't assume that the issue lies in the mafv--g/s table.

I guess my question becomes: is it possible to run that much higher of a load due to cold weather or is my intake cal not loaded correctly and I am not realizing it?

ambient air temp has a huge effect on pumped air mass.

 

Well, I went out and retuned the maf table. it is back to stable 11:1 at WOT and I spot checked the rest of the fueling in a typical drive cycle. It got up to about 68 degrees today and before the retune of the maf it was just as rich as it was last night when it was 35 degrees so I don't see how it could be an IAT correction if that was the case and like I said SS @ subaru of gwinnet advised me that he doesn't change any IAT corrections for bigger than stock injectors. I will double check tonight when it gets cold again.

Thanks for the help ride.

 

Double check your wastegate compensation tables. Make sure they are negative values and not positive. Jumping up to a 4 load is crazy. Also are you running the stock intake calibration calibration or did SS adjust the values to get closer to target afr's? Another possibility may be the boost/coolant fuel compensations. If either value is significantly off then the ecu dumps fuel for saftey. This table is not available in ST but is available in protuner and enginuity. Just a couple of thoughts. I would assume that something else if off such as tables you do not have access to that are not rescaled such as the high det. fuel map and if you hit a 4 load then my assumption is that is enough to cause the ecu to switch into the high det map which in unaltered form has a max load of 2.75 and runs rich in the 9's.

 

I think what happened was that the correct maf table was not loaded. Isn't the maf table the only thing that determines load? If so then that is what happened caused my loads to be so high.

Anyone know for sure what determines the load?

 

Unless the values are significantly higher in the MAF table then there is no way it would have hit 4 load on the stock turbo. Also the higher the MAF the richer it will run. If you are running the stock intake, there is really no need to change values within that intake cal. table. If anything the tune would have probably decrease MAF values to get target AFR's to get closer to actual.

Yes the units for calculated load are g/rev. Therefore its the reference MAF value (g/sec) * 60 (sec/min) / RPM (rev per minute). I suppose if you did exceed the max airflow value stock 300 then that would have caused you to run rich and maybe hit 4 load. If you want to post an image of your before intake calibrations that could be an easy indicator of if it was that much off or something else happened.

 

Unless the values are significantly higher in the MAF table then there is no way it would have hit 4 load on the stock turbo.

I don't think you can hit 4 load on the stock turbo. Even with 23-24psi midrange you are only hitting about 3.6-3.7 load.

Are you sure you weren't accidentally looking at the MAF voltage?

t

 

Man, you guys think I'm really stupid don't you? It was a 4.0 load. the g/sec were at ~250 g/sec. Which I know should not yield a load of 4. I will post the datalogs as soon as I resolve my excel issues. (I'm just kidding about the stupid part and I do appreciate your help)

Also, my current maf table has ~230g/sec for a peak load of around 3.3 (this maf table is hitting solid 11:1's at wot and is pretty good elsewhere as far as part throttle fuel targets)

Does this sound right to you guys?

 

Alright, based on some quick calculations (using crystalimpreza's formula for load) my problem was in my maf table. The load for the maf volts that I logged should have been 4.0 so in effect my MAF table was off greatly (the g/sec were way to high) and that also explains why I was running so rich. I don't know how well I stated this before but I reset my ecu right before all this stuff started happening and I was confused as to which MAF table was actually loaded onto the ecu.

A few questions come to mind:
How many maf volts is typical on a stock intake sti?
Also, how many g/sec are you guys pulling on your stage 2 setups?

I actually have an APS Inlet tube with the stock intake before it so I think that may be causing me to get higher than normal MAF voltages (that's my theory and it can be somewhat validified if someone can offer up some numbers for another stage 2 with a stock inlet tube).

Once again, thanks for everybody's input.

 

With a lowered intake calibration due to my meth to lean out my AFR's and at 22psi I hit somewhere around 255~260 g/sec at around 4.57-4.61 volts. With this calibration, I hit around 3.15~3.2 load at peak VE.

If you reset your ecu via ST or the AP then the realtime map should still be loaded. If you did a hard reset via disconnecting the battery than the basemap calibration would have been loaded. Why do you have different calibrations loaded in the base/realtime maps?

 

On a stock intake STI you can expect ~4.6 (give or take) MAF volts with a tuned stage 2 setup.

With an APS inlet tube you will get higher MAF Volts for sure. Not a huge difference, but you will see a difference.

With my 70mm MAF I am pulling 4.45 MAF volts for about 290g/s.

Also ...

my current maf table has ~230g/sec for a peak load of around 3.3

^^^ I am not following this comment. The MAF table is Voltage vs. g/s. There is no load indicated anywhere on the MAF table unless you are making a rough calculation by hand.

t

 

I suppose if you did exceed the max airflow value stock 300 then that would have caused you to run rich and maybe hit 4 load.

if he exceeds the max mapped airflow mass then the car will run increasingly leaner, not richer.

 

Wolf,

I meant that at peak load (and thus VE) I am pulling 230 g/s and that same peak load is about a 3.3.

crystal,

Actually if you reset via AP then it resets all realtime maps to whatever is on the basemap but I think you are right about using the reset ecu feature in ST not resetting the Realtime maps.

I ended up reloading the COBB stage 2 maf table and lowering the upper portions of it just slightly (multiplied by .97) to get the WOT closer to 11:1. All is well now.