View Full Version : Air Flow Rate limit
izaks
June 30th, 2019, 04:24 AM
PID: Air flow rate from Mass Air Flow sensor (Grams/s) maxes out at 655.35 . I have increased the value of UNM-16-11 (gps), but it made no difference to the logged maximum of 655.35
6.8L supercharged high boost running E38 at 10,100+ hz
Is this a hard coded limit or is there a way to increase the limit
GMPX
June 30th, 2019, 01:05 PM
I can't think of that PID name off the top of my head but '655.35' certainly calculates out (with scaling) to the maximum limit for an unsigned 16bit value (65535).
It will have a scaler of 0.01 so that is where the 655.35 comes from, unfortunately that is all controlled in the ECM code.
izaks
June 30th, 2019, 06:15 PM
Sorry, SAE.MAF
izaks
June 30th, 2019, 06:24 PM
I logged GM.AIRPERSEC, and it logs past the 655.35 limit
GMPX
July 1st, 2019, 09:25 AM
Glad you found an alternative, the SAE limit is just the limitation of that PID.
See here:
https://en.wikipedia.org/wiki/OBD-II_PIDs
22916
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