Quote:
Originally Posted by Unclemeaty
Seems our 370zs have two WideBand O2 sensors. I just have to confirm what they are, but logging options show bank 1 and bank 2, WB A/F ratio. The ECU as well has a pretty nice AFR target map for the mixture to reach, and then there is a closed loop correction % for hitting that target taken from the main fuel maps. The sensors can absolutely be logged along with up to ~20 out of ~50 other sensors.
What you mean by half-mafing is adjusting the precision of the MAF to where the ECU will start hitting values to the leftern parts of the maps rather than values all the way to the right.
So in the Subaru world... Your MAF sensor<s> can go up to 300 g/s? I presume that is pretty close to the 5v mark and about ~300-325 WHP on an AWD turbo car. That about right? Im not educated on Subaru, but I'm sure you've got a different MAF sensor and as we've got two in our 370s.
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Half mafing is where you take any tables that are referenced to load (where load is derived from the MAFv values and an equation, where calculated load = (g/s*60)/RPM) and then half those values. That way when your hitting a load of 2, its actually a load of 4 and your just tricking the ECU into being able to account for more airflow. You loose resolution doing this, but its better than just plugging in a really rich value in the last cell for open loop fueling, and hoping that it is rich enough to account for the air past the 268 g/s limit so that the AFR is right. As you can imagine, in that case, the AFR would swing rich, then back lean again.
So as an example, all the loads in the ignition advance table, and the fueling are halved, and the injector scalar is halved, and any other table that references the MAFv is halved. You don't have to halve it, you could say, use a value of 75% or something. But the thing you have to remember is when you data log, the values will be different. Its a tricky thing to wrap your mind around, and I honestly wouldn't recommended it without knowing for sure that other tables are not referencing the MAF to apply compensations.
The thing about g/s is it doesn't necessarily mean you can predict the MAFv. There should be a table that is called a mass airflow sensor calibration (or something similar) where a voltage range (1-5v) is correlated with the appropriate g/s for that voltage. These are the values you would change to account for a CAI bringing in different g/s than the stock intake, for a similar voltage.
I'm sure the Subaru MAF is different. However ours don't read past something like 4.76 volts. My 300 g/s is hit at that voltage, however I'm only at like 4.6x volts.