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Discussion Starter · #1 ·
I wanted to have some kind of traction control for the street. The time based options are expensive and don't accomplish what I want. Here is what I've come up with.

This is based on comparing the front wheel MPH vs the rear wheel MPH and pulling timing if they get too far apart. I used the stock VSS off the transmission for rear wheel speed and an SN95 ABS sensor for the front. A previous owner did a 5 lug conversion with SN95 spindles so I already had the hole for the sensor.
Wheel Automotive tire Gear Motor vehicle Saw


Unfortunately, my hubs didn't have the tone ring so I had buy a new hub.

With the sensor installed:

Automotive tire Rim Bicycle part Automotive wheel system Auto part


Both are VR and produce a sine wave that is converted to square wave with two of these:

Data transfer cable Font Cable Parallel Wire



In the Holley, I configured the two inputs like this:

Font Audio equipment Display device Technology Electronic device


Front:

Font Screenshot Clock Electronic device Display device


Rear:

Watch Font Clock Screenshot Electronic device


Even though I run a 3.31 gear, I had to put the gear ratio in as Drive Teeth/Driven Teeth*Gear Ratio to get the MPH right. Once I verified the Rear MPH with GPS, I made small tweaks to the tire diameters to make front and rear match. I've errored on the side of making the front slightly faster (maybe .25 MPH).

To reduce power to keep it from spinning, I'm using a 2D table to retard timing:

Rectangle Font Software Screenshot Electronic device

Colorfulness Rectangle Purple Font Line


Here is a data log of it at work:

Black Rectangle Slope Font Line


This was all three gears (C4) and WOT from a 15 MPH roll. You can see the tire spin shown by the distance between the lines and MPH values on the left. It starts spinning slightly and gets worse as the turbo spools. It pulls timing and then adds it back in when it gets some traction. Without this table active, it would have hit the rev limiter as soon as the boost (8 psi) came in. 2nd gear is almost as bad. 3rd is a crap shoot. I'll try to get another log this week with the table disabled to show the difference.

I still want to do some adjustments to the timing table. I've only worked in the 1st cells, used -25 as the max, and used the fill function to populate the rest of the cells. I started out with -10 in the 1st cells and it wasn't enough. -15 is working but I think I need to be more aggressive in the next cells. It seems like a 4-5 MPH difference is the max difference you can have and it still be controllable. More testing will tell.

I may move to gear based tables to get more resolution. The gear based tables will also let me be less aggressive on the timing retard in the higher gear. For now, I'm happy with it. I roll around on 275/60 Radial Pros and even with those, it would get sketchy going WOT from a 60 MPH roll in 3rd depending on the road.
 

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Excellent! I don't have a Holley but TC makes high HP cars damn fun!
Good to see someone playing with it!

For reference I also use 4mph as the limit before TC kicks in and I could try 3mph.
I have to be extremely aggressive when pulling timing to control spin so it pulls timing to -25* ATDC instantly. Anything less and tire spin can't be controlled before over revving.

I'm not sure how the Holley adds timing back but MSPro adds timing back just as fast as it is pulled (not gradually) so looking at the log file it shows timing going from 11* (max timing while in boost) yanked back to -25* when spinning then back to 11* then back to -25*, it's kinda violent and I haven't been able to smooth it out yet..

ks
 

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This is a kick ass write up, thank you for contributing. Something I might want to use as well.
 
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Discussion Starter · #5 ·
I'm not sure how the Holley adds timing back but MSPro adds timing back just as fast as it is pulled (not gradually) so looking at the log file it shows timing going from 11* (max timing while in boost) yanked back to -25* when spinning then back to 11* then back to -25*, it's kinda violent and I haven't been able to smooth it out yet..
Holley is the same. Timing is whatever is happening in real time. I was worried about the scenario you describe but fortunately, it doesn't do that. It doesn't have to control as much power as you are making so I think that helps a lot. I haven't had it on the dyno but based on fuel flow and some math assumptions, it's probably 580ish RWHP on 8 psi. With the timing reduced to 8 BTDC, it's has to be below 500.

Once I get a control on 8 psi, I'll turn up the boost to see how it reacts. I wish I could create my own PID loop to control how it ramps the timing back in but there isn't an option for that in the Holley EFI that I've found.
 

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You are doing the same setup I did on my car back in the day. I finally just moved to a Dominator and Profiler for my TC.

The setup works, it’s the hard ramp back in can cause issues down the road. I wish they would allow for some sort of PID but they don’t.
 

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Discussion Starter · #8 ·
Found a video on you tube where I guy does it a little differently and I think it's better so I've made some changes.


You create a PWM table within an output:

Font Audio equipment Automotive lighting Display device Gadget


Colorfulness Rectangle Slope Line Font


This creates a table for % of wheel slip.

Then you create a new 2D table of Wheel Slip vs Front MPH:
Colorfulness Rectangle Font Slope Line


Have the Wheel Slip table created in an Output for reference lets you create another table to modify the rev limiter to drop cylinders to further help with the wheel speed control:

Colorfulness Rectangle Slope Purple Font


Configured a new datalog view for just traction control:

Rectangle Slope Organism Font Terrestrial plant


This works better I feel and gives me more resolution without having a 2D per gear table. Keeps it all on one.
 
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Discussion Starter · #11 ·
I'm using HP. I've looked at Term X some and I think it will do this too.
 

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Discussion Starter · #13 ·
A little update after some tuning. Here is where the two tables sit now.

Timing:

Colorfulness Rectangle Font Screenshot Slope


And the Rev Limiter Offset:

Colorfulness Rectangle Purple Font Line


When timing can't control the traction, the rev limiter table comes into play and starts dropping cylinders.

This is a datalog from a dig:

Rectangle Black Slope Font Line


You can see where the rev limiter is lowered when the wheel slip % gets too high for just timing to control. It's very soft and subtle. It just touches the rev limiter here and there in 1st, none in 2nd since timing is able to control it, and then in 3rd there isn't enough wheel slip % to get any timing pulled.

You have to set the main rev limiter to soft for this to work:

Rectangle Font Parallel Technology Screenshot


Overall, I am extremely happy with how this is working. No more worries about it getting out of shape on the street. One of the best things I've done with to this car. I was going to add a traction control button so I could turn it off with a switch instead of disabling the tables but I'm out of inputs :mad:
 

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Discussion Starter · #15 ·
I saw that. Might do that in the future if I find the need for more I/O. At $367, I'll click a couple of boxes to turn it off.
 

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Discussion Starter · #17 ·
Single coil and TFI distributor. From the Holley forum, this is how they describe the rev limiters:

Description: There are 4 options available.

· Fuel Only – performs a “hard cut” of fuel flow only when the main over-rev HIGH RPM is hit. “Hard cut” means that fuel flow is stopped to all cylinders until the main over-rev LOW RPM setting is met.

· Spark Only – performs a “hard cut” of ignition only when the main over-rev HIGH RPM is hit. “Hard cut” means that ignition is stopped to all cylinders until the main over-rev LOW RPM setting is met.

· Fuel and Spark – performs a “hard cut” of ignition AND fuel flow when the main over-rev high RPM is hit.

· Soft – begins a “soft cut” of ignition when the main over-rev LOW RPM is hit. “Soft cut” means that ignition will be removed from individual cylinders as needed to limit RPM. If the HIGH RPM limit is reached, a hard cut will be implemented
 

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I'm a big fan of the soft. When I've hit it doing open track stuff or roll racing it's extremely forgiving and gentle on the engine.
 
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