Traction control algorithm

[thedrew]

Traction control question --

I have three wheel speed sensors now (RWD)--

VSS1 - right rear wheel
VSS2 - front wheel
VSS3 - left rear wheel

It says it computes slip based on driven vs undriven, how does it take into account the 2nd driven input (or at all)?

Thanks!

[dontz125]

Assuming this is a RWD with a non-limited-slip diff, you might be better off having VSS1 on the drive shaft. If your RF and RR wheels are stopped because your LR is spinning helplessly, the TC won't trigger.

Alternately, you might consider a circuit that passes the highest frequency / voltage of the two rear sensors to the VSS1 input of the MS.

[thedrew]

so the TC code only takes into account VSS1 and VSS2?

[dontz125]

From the tooltip:

Traction control method:
Perfect Run = a drag race strategy for a single pass comparing actual VSS against best possible.
VSS %slip = compares VSS1 to VSS2 and detects slip%.
Perfect Run RPM = similar to perfect run but without VSS for classes where that is not allowed.
Switch input = for use with an external slip detector.

Off hand, I can't think of any function that actually uses the VSS3 /4 inputs. Perhaps a diff-locking function might compare left and right, but right now I *think* it's just datalogging.

[thedrew]

just thinkin out of the box here....maybe the code could check the freq of all 4 vss's (if available) when on slip % mode. Would be alot easier than rigging up a freq checking circuit.

Its a 74 bug with a trans axle, no driveshaft!