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Unfortunately, we cannot directly measure the difference between rough roads and smooth ones. This is within the capability of the observer, but in order to have that level of precision you would have to have much more accurate sensors. Specifically, you'd need a danged good elevation profile for your road. Also, a throttle position sensor would help.
the TPS value will NOT help.
the MAF or MAP (on speed density systems) value will
and
better still (as stated already in this thread )
the calculated load PID will
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with the mpguino Can
they are using OBD2 data to make the calculations
on many systems using AFR sensors ;
you can not use an analogue connection to measure all AFR sensors
some use changes in current flow , very small changes and there is no easy way to break into the harness to get an accurate measurement .
but
you can use the STFT or EQ ratio value in OBD2 generic data as the output of the AFR sensor is directly reflected in
STFT and EQ ratio -
if your scan tool has a fast enough update rate and can graph the data
you can get some really neat graphs going after only 1 or 2 PIDs at a time
and
you can flag a biased AFR sensor IF it does NOT center on ZERO trim or Lambda on most systems
you can get a basic idea if your MAF sensor is reporting correctly by
comparing calculated load at WOT over 4k rpm in 2nd gear uphill
calculated load should be very close to 100%
do not use the absolute calculated load PID , values will always reach 100% and they will not be correct
If there is a BARO calculation (ford) it better be accurate for local ambient BARO pressure at the time , other wise suspect incorrectly reporting MAF .
if calculated load is less than 100% under WOT as described above
and the system is still in fuel control and NOT open loop , look at fuel trim
IF SUM of fuel trim s is adding more than 10%
expect an underreporting MAF or restriction to fuel flow
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