MAF Airflow Limit 2016 Mustang GT

[Blown383]

Today I tuned a 2016 Mustang GT w/ KB 2.8H. At around 6600 RPM, MAF Lb/Min in the scanner would flatline at 86.69 lbs/min. Is that a hardcoded limit? Everything looked fine so I proceeded to tune it no problem. Zero issues. MAF Period continued falling as normal. Fuel trims and wideband stayed in line. I know were at the limit for the MAF housing but is there anything I should worry about flat lining the MAF lb/min like that? Thanks.

MAF1.PNG

[Witt]

It's a limit on the sae pid. Applies to other makes as well.

[Jn2]

SAE PID limit, but not the limit of the MAF, you can see that MAF period will keep dropping lower and fueling should stay accurate.

[murfie]

PIDs that return 1 byte have a limit of 255
PIDS that return 2 bytes have a limit of 65535
These are the highest decimal value that can be represented with the limited bits.
MAF is limited to 655.35 g/sec. Its formula gets divided by 100.
They all have limits, RPM would flat line at 16,383.75 if you could get the engine to spin that fast. The formula divides it by 4, so you can see the 65535 value.
SAE MAP channel would be limited to 255KPA or ~22-23 PSI of boost. Middle of your 3 bar MAP sensor range.
255 Km/h or 158.45 MPH.
Go to the wiki page to see the limits of others. https://en.wikipedia.org/wiki/OBD-II_PIDs

[Blown383]

Awesome. thanks a lot guys. I figured it was something like that. I knew in the back of my mind the newer ECUs, 05+ didn't have airflow limits that low but wanted to make sure.

[Jn2]

Awesome. thanks a lot guys. I figured it was something like that. I knew in the back of my mind the newer ECUs, 05+ didn't have airflow limits that low but wanted to make sure.

it's a SAE PID limit, so 05+ would hit the same 86.69#/min limit that the coyote would, this is not the limit of the MAF, only the PID, the ECM still calculates airmass just fine past 86.69#, the PID just can't display it

[Thatwhite5.0]

If you'd rather it not flatline, you'd need to rescale and recalculate your inverse tables by increasing the last row's axis value in inverse. Theres also a limiter you may or may not hit when engine brake or etc torque request exceeds 730ft lbs.