RomRaider

So I may be way out in left field here but while really looking at all the tables in a couple of different roms tonight I noticed that the "Primary Open Loop Fueling" table contains cells that appear to be beyond the capability of the front 02 sensor?
In other words, from about 1.2 g/rev @ 4K rpm and up, the cells read below 11.1 (estimated) AFR.
The "Front Oxygen Sensor Scaling" table only goes down to 11.1 AFR
The "Primary Open Loop Fueling (failsafe)" table contains values that are even lower than 11.1 AFR (9.96 AFR for a stock rom on an 06 WRX).
I must admit that the light bulb in my head with regards to open source has not gone off yet. I am struggling to grasp how everything is tied together, I spend at least 2-3 hours an evening reading and trying to grasp just a little bit more every day.

My current tune is set to run at 10.75 AFR from 2.0 g/rev and up above 3800 RPM or so. as seen in the image below.

The million dollar question I have is: HOW is the ecu controlling fuel delivery at AFR's below 11.1:1 ?
What does it do when it reaches the lower limit of the front 02 sensor? and how does it know if the AFR is pig rich at 9:1 ?
My own observations and logs confirm that I am hitting the AFR targets in the cells in the "Primary Open Loop Fueling" table because I can log my wideband, and when I also log my front 02 sensor, it pegs at 11.1 while my wideband shows that I am in fact hitting 10.7 or even richer in some cases.

This has me really confused.

The values in the open loop fueling table are just enrichment or enleanment values. How ever you want to look at it. The value lets you modify ipw for a different load and rpm cell. The ecu isnt looking at the 02 sensor after it transfers to open loop fueling. Your ipw is set and the fueling map modify's it as the ecu reads through the cells as the rpm and load changes.

The answer is simple: the ECU doesn't pay attention to the O2 sensor in open loop.
That's actually what the term "open loop" is all about.

Closed loop:

1) look at load value, and the currently AFR correction, and decide how much fuel to inject to reach 14.7 AFR.
2) inject fuel
3) compare the current AFR to 14.7, calculate a new AFR correction
4) go to step 1

Open loop:

1) look at the load, and decide how much fuel to inject to reach the value in the Primary Open Loop fueling table.
2) inject that much fuel
3) go to step 1

Those aren't exactly correct, but conceptually speaking, they're close enough. Using AFR information as an input to the fueling equation "closes the feedback loop," hence the term "closed loop." In closed loop, the ECU uses the O2 signal to keep the AFR on target. In open loop, the ECU simply injects (what it hopes is) the right amount of fuel to achieve the mapped AFR.

But that is my point, (the part I highlighted) is how does the ECU know when it has hit the target ? especially in load/cells where the target AFR is below the ability of the 02 sensor....or... if as stated, the ECU does not look at the 02 sensor in closed loop, how the heck does it know how much fuel to add/subtract.

The fueling table is what it uses. Romraider lets you see values in afr or lambda but the ecu is seeing offset to pulse width either + or - the pulse width from the scaler value and whats in the maf scale and comps.
In other words it adds or subtracts from the cc/min in the scaler value plus or minus from the maf scale and plus or minus some comp tables.
Man thats complicating!!!!

The ECU doesn't know when it has hit the target. It does some math to figure out how much fuel should reach the target, and then does a little more math to figure out how many milliseconds of injector pulse will squirt that much fuel, and then it pulses the injectors for that duration. Period.

In open loop, ECU just assumes that your MAF scaling and injector settings are correct. If those assumptions are wrong, the AFR will be off. This is why it's so important to get the MAF scaling and injector scaling correct.

Actually, I'm starting to have doubts that even getting the injector settings and MAF scaling correct is sufficient for FMIC'd cars. That's a whole other story:
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