Next on the agenda is looking into changing the ABS setting for the front brake bias to see if there’s any discernible change in the car’s braking distance.
I got started today recording a couple of braking events, starting and 60 mph and slowing to a stop, or just about stopped. So that I can conduct this exercise more easily I record the ECU data using ME7Logger and then the time stamp and vehicle speed to find the distance travelled. The results using this method may not be valid for comparison with tests where a true distance measurement is taken, but in the interest of getting some results to look at I’ve chosen this method.
The time and speed data is crunched via an excel macro and the distance is calculated, along with an estimate for g-force’s during the deceleration.
The first two test runs are shown on the two charts below:
To check for consistency I plotted the distance versus time for the two test trials.
Those are clearly NOT consistent results. I will need to make a few more trial runs before I have enough baseline data to feel confident about moving on to recording comparison data with the RS4 brake bias setting.
This chart also reinforces my belief in making multiple runs to get a number of data points to consider. All too often I read about tests being performed where a single reading is taken before, and then a single reading taken after, with the results being presented as definitive proof of a change, or lack thereof, attributable to the one variable (out of many) that the tester chose to consider for monitoring.
Returning to the test I performed. I began at sixty miles per hour and decelerated to close to 0. When the readings start to get near to zero it seems that the data value from the ECU becomes very small, but zero is not reported. This creates errors as it leads to calculating additional distance traveled that may not be occurring. My solution to this limitation in the measurement system is to call 1 mph close enough to zero to be the stopping point.
For the purposes of the check I am interested in, whether adjusting the ABS bias improves braking performance, my hope is that this measurement challenge is mitigated by being able to compare several curves and that the trend line will be indicative of a change, or no significant change. This would lessen the importance of the overall distance measurement.
The next step in the test is here.