Megasquirt Hemi Gold Box -%slip Traction Control - Works!

Sharing my current progress on a rear launch control/max acceleration strategy for the 'Cuda.

I have a VR output shaft speed sensor that has proven to be accurate on my T56 Magnum. This will serve as my driven-wheel speed sensor. In order to have a proper street car traction control, I need an undriven-wheel speed sensor.

Up front I am using the internal section of the rotor cooling vanes as my pickup [32t/rev]. I have talked to two other Megasquirt users that have done this successfully, we shall see how it works. The sensor is a $25 Cherry brand off of Amazon and is a nice stubby all-thread for very good range of adjustment.

I have fed shielded 3-wire cable through the firewall for the VR and Hall Effect in an attempt to mitigate interference.

Hopefully this week I will button up the front sensor wiring and generate a signal. After that I should be off to tuning the traction control. This will complement what I have setup already for launch control and flat-shift.

My goal is to mimic some of how this car in the video operates. Managing a %slip from front to rear via pulling timing to provide the fastest acceleration. It will compensate as much as it can for tire grip and surfaces to keep the car moving forward.


https://www.youtube.com/watch?v=FembJNagxOE

Now to put it back together and tune it..

https://www.youtube.com/watch?v=rprVqfdYR00

That’s a slick set-up. Your car is a perfect blend of a modern car with vintage sheet metal...

This is interesting. Retarding timing based on driveshaft speed and front wheel speed. Could you show how you do that in MS?

It may depend on the box you use, but the ms3 has built in launch and TC. I can try to post some screen shots this evening.

Thanks that would be great. I guess it would be similar to retarding timing vs boost.

Screen shots attached. I on using the spark retard vs time.

Bit confused on the Slip x Time. What are the increments of time? Is this something a user inputs?
Looks like you get a lot of features for the money

So I haven't played with it yet, I'm sure it'll start making more sense once I dig into it.

Yes, the user inputs the degrees of timing to retard and can adjust the magnitude of slip as-needed. The colored cells can be changed and drive what shows up on the graph.

As you can see in the note, it is slip [1-(WSS/VSS)] multiplied by 0.1s. In a basic form, I believe it is just the magnitude of slip you are experiencing. A little slip pulls 3.0°, a lot pulls 20° and the ECU will interpolate as needed to hit the target %slip value shown in the setup features [1st image in previous post]

Yes, the MS box offers many features that I think many people over look, or even don't "need". But you need to take advantage of them if you want the most out of it. This is stuff I'd never dream of playing with using a Mopar ECU...

Ok, I didn't see the little note - Slip% x .01 sec
Since the interval is .01 sec then 2.5% slip for .1 seconds becomes 25 slip "magnitude".

You need to get a Whipple supercharger so you can take full advantage of the traction control.

Very Cool, that is something I plan on doing to mine. Mine won't have the resolution yours does on the front because I will be using the bolts that hold the rotor to the hat since I do not have vented rotors. Now lets see some vids of it in action!

Turned it on this morning and it tried to correct for slip slightly. I have some noise on my VR sensor at higher rpm that I need to lose, or convert it to a Hall effect. At least the software and inputs are working, it’ll be a learning curve to get it dialed in.

Are you still using a separate 5V source for your sensors? If so is that 5V converter getting its power and ground from the same place as the megasquirt? Anything that feeds info to the MS needs to share power and ground with the MS.

VR generates its own AC voltage which is converted to digital signal/conditioned in the ms ecu. That’s why they are susceptible to noise. The Hall effect sensor is on its own 5v and doesn’t appear to have any issues with how it’s wired.

Ahh OK I forgot VRs make the voltage, I run all Hall sensors, crank, driveshaft, and I will run one on the front when I get around to it.

Flatshift feature in action.


https://youtu.be/QdP39A-MyiU


Yes, I need new tires.

I've been able to get the traction control work!

Perhaps a hair too aggressive, but it is interfering. This run would have been nothing but major tire spin and not much movement going forward through first and second.

The traction control stepped in and kept the car straight, it's hard to know if it accelerated any faster, but that's what tuning should start to tell me. The green line is reduction in ignition timing due to wheel slip.

https://i.imgur.com/BykV8X7.png

Very cool.
Following!