actual afr is 0.4-0.6 leaner at low loads and 1.0 leaner at high loads, comparing to map's afr

it's evo3 with evo8 ecu, AEM uego installed in test pipe, ecu was in forced open loop while testing

again and again thinking about MAF scaling is incorect or what could cause it ?

 

It does not matter if map AFR doesnt match actual AFR. The number in the map is just an arbitrary number. Higher number means leaner, a lower number means richer.

 

Jay is right, but your MAF scaling may still be wrong. A lot of people using the 8 ecu with 2g dsm/evo 1-3 MAFs have the wrong scaling.

 

+1 yes the true AFR and AFR number on your fuel map rarely ever match, and is never meant to.

also dont get confused by wreckleford's comment... its not incorrect but then again most USDM evo owners do not upgrade the maf, except to remove it for speed density. actually something simple as going from stock intake box to cone filter can throw off the maf scaling abit also.

the question is do you truely have an issue or are you assuming you have an issue simply because your true and map scaling AFR doesnt match?

 

wreckleford
then it's not a problem to have incorrect maf scalings ? doesn't it affect performance, afr, etc..?

mifesto
I'm just assuming it, because don't know if that scalings are correct, I just copied the table from another forum member, who stated that it was correct maf scaling, that he used on his evo2 with evo8 ecu
I just want to map the car (maby will switch it to constant open loop and map that way) and wondering if the incorrect maf scaling can be disturbing factor any way. If it's not a problem and I can disregard this thing, better for me, one less thing to think about

can you confirm it ?

 

MAF scaling will affect fuel trims more at cruise and idle if they're off. Both latencies and MAF scalings can be adjusted to fine tune fuel trims and youre goal is +-5% low and mid ltft. If you throw a filter or new intake on the car it can scew those numbers and cause the car to run more lean or more rich and affect fuel consumption. You can pretty much disregard it in boost unless someone is screwing with the scalings in that area.

The 14.7's up to 100 kpa load are pretty much right on since the o2 is constantly trying to target 14.7 afr but after that you need to adjust according to the AFR sensor, not what the table says.

 

thanks for your input guys. so it's not a disturbing factor for mapping the car, as I've undertand

 

think of the fuel map as a compensation, rather than a target AFR.

its 14.7 in low loads, but really it's 0 compensation, the raw value is 0x80 (128), the ECU does this a lot of time, uses 128 as a middle value, either side is either more or less of whatever you are compensating.....

in hindsight it was probably a bad idea to use "AFR" in the fuel maps since it confuses some people... but it's stuck, and I doubt if it will ever change...

you can dial your MAFScaling in more/better to get the Fuel map to be a closer approximation of your actual AFR, but really its not necessary...