Originally posted by azgn
any chip worth its salt cares less what the maf is reading at wot (assuming a stock maf that won't read beyond 255)
fuel tables are derived above that level based on experience, your build, etc
The only chip that doesn't care about the MAF reading is the MAFless ME. While there is little change at the very top end of the MAF readings fuel wise, the gm/sec is used.
What people do is figure a fuel curve, based on what makes the engine run best, at WOT. In reveiwing alot of DS datalogs you'll note odd commanded WOT AFRs. Some are set just to run the injectors static, and some are AFRs that are for air flows higher then the ecm can calculate.
Just by example, and picking numbers easy to use.
Say you see a data log with 36 PPH injectors and a commanded AFR of 6.5:1. Obviously the engine wouldn't make max power at that AFR. If you look at the PW graph of a DS for that combo, you'll see the duty cycle is 100%. So if you were to do the calcs using a reasonable AFR you could figure out what the actual gm/sec were. And a rough estimate would be like 300 gm/sec.
Now, say you look at a data log for 72s. Now you see a commanded AFR of say 9.5:1 and a DC of 80%. Now in this case the engine is say flowing 400 gm.sec and being fueled at 12:1 actual AFR.
Now, in the first case you tune by twisting the wastegate, since there is no actual fuel curve, since the injectors are just static.
In the second case you can taylor the fuel to actually develope a curve and match what the engine needs at some RPM points.
But, neither are actually reading over 255, and run *too* rich up until the air flow matches what the injectors are doing.
The exception being the translators where they can read over 255, and the MAFless MEs since they don't use the MAF.
To actually match the fuel at a number of points thru the rpm/ load points does take an aftermarket or rewritting the code for the original ecm.
Jackson's gone an 9.6 with a stock ecm using a MAFless ME so the stock computer can run well on fast cars.
Just an matter of what options you want to take.
To get past static injectors is gonna take some money. Just a matter of seeing what your thinks most cost effective for you.
