I never understood the why the stock injector scaling is different in USDM/AUDM roms (513) than JDM (542)?

But my question: does such variation make any difference when scaling larger injectors in any rom version?

 

Grayw siad it was something to do with the USDM cars having injectors with a different spray pattern. Maybe to do with emissions?

 

So, USDM injectors are physically different?
Which means that that the scaling should be changed to 542 when using a USDM or AUDM rom on JDM/EDM cars... correct?

 

I would suggest it maybe a good starting point. From there test the settings against the fuel trims, the latencies can actually make a big difference, but start with the scallings.

 

All evo 560cc injectors flow the same i dont buy into the different type of injector theory at all , what scaling works well on one doesnt necessarily work on another ,just get the trims within +/- 5%

 

I don't currently have an issue, I'm just curious about this difference. A similar case is found in Ceddy's rom, in which the injectors are scaled at 575 (DSM) I never understood why, is it just a measurement difference?

 

The fuel calculation code is a little different. JDMs always end up with slightly different injector scaling to the "norm".

 

Maf scaling or compensation is different between the two type of roms

 

I was tuning a JDM E9 MR, I calibrated larger injectors (1200cc) on the original rom (MAF) then I wanted to tune it with a V7 SD rom & the only rom version that seemed available was an AUDM rom with 513 scaling. So, I was wondering if my initial calibration values would work or if I'd need to rescale it again. If fuel calculation is different it means that the scaling would be different for any given injector size...? (JDM/EDM vs USDM/AUDM)
In my case, I ended up using a JDM V5 rom, so, I used my initial calibrations, but I thought to ask about it just in case if I pump into a similar case again.

 

https://www.evolutionm.net/forums/ec...djustment.html
I posted this a while back on the 513/542 difference.

 

According to Ceddy the 575 with DSM scale shows the "true" size of the injector, and the 542 with EVO JDM scale is what we usually select in the Ceddy rom variants. But no fueling changes are being made when changing between these two scales cause you´re not manually changing the injector size or flow in Ecuflash, it´s just a different scale; like going from °F to °C doesn´t chage the temperature.

 

Well this is not about different reading. There are 2 ways how to scale stock 560cc injecotrs:
1 513scaling + latency table + maf scaling
2 542scaing +(it's own) JDM latency table +(it's own) JDM maf scaling
You should not use 513 scaling with latencies from 542 and/or maf from 542...
Both makes indentical afr, but works a little different.