Traction Control
In order to set up the Intelligent Traction Control, we first need to know how much driveshaft rpm acceleration is normal before the tires brake loose and we see a spike in the rate of change in the shaft rpm per one tenth of second. Using the data logger and in the safety of MCR's parking lot, Brian adds throttle until the tires brake loose. About the greatest rate of change the tires can handle is an 84-rpm increase per 0.1 second, also known as delta driveshaft rpm.
With this info, Brian can set up the parameters for the ITC, such as the minimum TPS percentage required for the ITC to operate, as well as minimum and maximum driveshaft rpm. He settles on a Delta DS RPM of 100, which means that if the driveshaft rpm increases faster than 100 rpm in a tenth of a second, the ECU will begin to pull timing until the rate returns to that level. He can then make another pass using the data logger again to see if enough timing is being removed to control wheelspin. If not, the rate at which timing is removed can be increased until wheelspin is controlled.
On the vertical axis is the amount of timing removed and the horizontal axis is the rate of change of driveshaft rpm or Delta DS RPM. Notice that the graph starts at a Delta DS of 100 with no timing retard and that the amount of timing retard increases as the rate of driveshaft rpm change increases. (If the Delta DS RPM is set too low, the ECU will pull power under hard acceleration, even if the tires aren't breaking loose.) The benefit of this method is that engine rpm and road speed are totally ignored, so it will work under any conditions as long as the minimum parameters are met (TPS percentage and minimum driveshaft rpm).
Here you can see a zoomed in portion of the traction control part of the data log. The top trace (pink) is actual driveshaft rpm. The green one is the amount of timing retard occurring. Notice how the timing retard closely parallels the Delta DS RPM curve (light grey) indicating that the Delta DS RPM is being very tightly controlled. The maximum amount of timing retard was only 10 degrees.