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Originally Posted by thambu19
@ arghx7 @ solidONE @ steve99 @ Kodename47 @ ztan
My concern is if the fuel trims go up or down too much say more than 10% it will take the estimated load along with it. Estimated load = Originally assumed load through MAF signal +- corrections from fuel trim. This means the cam and spark lookup will move around unnecessarily?
I dont know how exactly it works on the FA20 so this is just my assumption. This is assuming that most OEMs trust their fuel modeling more than air flow modeling. So when fuel trim moves the load estimation moves as well. |
You're giving Subaru too much credit. It's not that smart, or at least, not that anyone has proven. Unless someone here wants to link to somewhere showing the load estimation being related to fuel trims. It certainly never did that on the EJ engines.
The code is really not that sophisticated. There's no combustion model based spark control either--or if there is, it doesn't matter enough that anyone has bothered trying to understand it. Have you seen the cooled EGR spark controls on the FA20DIT? It's just a dumb look up compensation table, or at least the one that has been found so far seems that way. No residual gas model aspect to it.
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My other concern is how is MAF scaling going to fix this? For example say if by going 100%PFI at low loads causes the LFTF there to go 10% +ve causing a load estimation to go up 10%. The MAF there would be moved up 10% at the same Voltage to bring the LTFT to 0% but we still have the same problem because now the MAF readings are higher (artificially) causing a higher load estimation and hence spark/cam lookup = bad combustion or knock depending on which direction we go in load lookup
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MAF scaling has always been strategic tail-chasing in this context.