Help me to Understand the Traction Control Tables

[bluegoat06]

I've eliminated most of the TM stuff and part of the traction control system modifying the following tables:

Trans Input MAX, stock: 2952 ft.lb Modified to :6046 ft.lb
Trans Output MAX, stock: 5904 ft.lb, modified to: 6046 ft.lb

I've also modified the ETC TPS max from stock values to all 100's
and the Spark Retard vs Torque Reduction from stock values to all Zero's

Now that the winter is here, i've put back the stock values in the ETC TPS MAx and Spark Retard vs Torque Reduction, leaving the Trans Input and OutPut MAx alone at 6046lbs.

I'd like to have a better understanding on the values that i'm actually changing, i don't care about this any other time of the year since i rarely drive with TC on, but now that's im starting to see some tiny snow flakes, i'd like to be covered by the TC even though i'm not going to be plowing snow with this vehicle

so, ETC TPS MAX

The vertical axis have FT.LB values starting from 0 and going up to 708 ft.lb
The horizontal Axis have Engine RPM from 0 to 6400rpm
my question on this one would be about the cell values, reading from VCM editor help, this is the maximum allowed ETC throttle percent based on the current torque being delivered.

Here is where i get confused, my car idles at 11% ETC, what happens in this table when i stab the throttle in 1st gear from 2500rpm. i did a little test today (Sorry i can't recall how the stupid TC system works since i've never used it before, even when i was stock), and my car spun the crap out of the tires, and i saw the TCS kicking in the logs about 1-2 sec later, so how is this Maximum allowed ETC throttle percent working on this table ?, does it remove or add throttle like a timing table would do? basically closing the ETC by the % value adding or removing from the main ETC on the cell, or just closing the ETC completely by the % value on the cell ???

The second and even worst to understand, at least for me
Spark Retard vs Torque Reduction

The Vertical axis has a % value, with numbers ranging from 0.0 to 100.0, what's the meaning of this % numbers ?
The Horizonal Axis has another % with numbers ranging from 0 to 80, what are they, % of what ?
and the cells in between have their values, based on ???


Any help is greatly appreciated.

[5_Liter_Eater]

Subscribing

I've never fully understood the gen 4 tables either.

[Chris@HPTuners]

The Trans Input & Output torque limits are maximum torque values. The PCM has the ability to calculate the torque through most driveshafts and axles and you can set limits for them. Usually only trucks have limits in place.

The ETC TPS Max is the maximum throttle allowed at any particular point. ie. setting this to 100% effectively removes any throttle limiting. It is not related to torque limiting due to the TCS system requesting torque. That is a reactive system initiated by the ABS (EBCM) module.

Teh spark retard is the amount of retard to command for a desired % torque reduction. Most systems request a percentage torque reduction rather than an absolute value. eg. the trans might request a 50% torque reduction during a shift, the PCM uses the spark table to convert that to retard. So 0% means no reduction and 100% means full reduction.

Hope that helps,

Chris...

[5_Liter_Eater]

Where I get confused is what tables are for "torque management" and what tables are for "traction control". I would like to know that I am not affecting/disabling my traction control while also disabling any torque management (what little there is on a manual transmission).

Also, there are three different methods of traction control (spark, ETC and fuel) but the only table you can adjust is the amount of torque loss per degree of spark retard; no tables for amount of torque reduction per ETC% reduction. So if I enable fuel or ETC traction control is it a total cutoff?

Lastly I would like to start playing with the ETC max table finding the sweet spot just before traction loss realizing this will differ based on different road types, tire temps, etc. Something like a histo to show the max ETC plotted against the ETC limit table with a filter of Traction Control Desired Torque >= Calculated Torque.

[Chris@HPTuners]

the problem is that the requested torque reduction from ABS initiated traction control is part of the ABS controller (EBCM). It requests torque reduction via the CAN bus. The ECM can be calibrated to use spark, fuel or throttle to reduce torque (just as the RPM limiter can). On E40 there is a direct table that the ECM uses for spark retard (it usually uses spark as the first choice becuase it acts the fastest). For throttle it uses the Max ETC TPS table (converts the % to a torque desired using current torque). On the E40 if you zero and 100% these two tables you effectively eliminate any spark or throttle torque management (there are some exceptions but i forget).

The E38 does away with these tables and uses a direct formula approach to calculate the spark retard and the throttle %.

On E40 and later ECMs the fuel cut is usually per cylinder depending how much torque reduction is requested, the older LS1 PCM was all or nothing.

Bottom line is if you want TCS to function normally then don't mess with these tables on the E40.

[5_Liter_Eater]

Is the max TPS table only used when TC or TM engages or is it used all the time? IE: could it essentially be used as a throttle stop?

[Chris@HPTuners]

i don't remember, try it and see

I *think* it is only used when reduction is commanded.

[5_Liter_Eater]

Yea, it would be easy enough to test.

Chris, aren't you in Vegas for SEMA? And you're trolling the forums from your hotel room? Come on man!

[Chris@HPTuners]

nope, back home now, SEMA was last week

[bluegoat06]

i don't remember, try it and see

I *think* it is only used when reduction is commanded.

and reduction is commanded only when the ABS system kicks in initiated by the ABS traction control system correct ?

where do the trans input/output max come into the picture if they do ?

are they actually used in the TC calculations to reduce spark at all ?

[bluegoat06]

the problem is that the requested torque reduction from ABS initiated traction control is part of the ABS controller (EBCM). It requests torque reduction via the CAN bus. The ECM can be calibrated to use spark, fuel or throttle to reduce torque (just as the RPM limiter can). On E40 there is a direct table that the ECM uses for spark retard (it usually uses spark as the first choice becuase it acts the fastest). For throttle it uses the Max ETC TPS table (converts the % to a torque desired using current torque). On the E40 if you zero and 100% these two tables you effectively eliminate any spark or throttle torque management (there are some exceptions but i forget).

The E38 does away with these tables and uses a direct formula approach to calculate the spark retard and the throttle %.

On E40 and later ECMs the fuel cut is usually per cylinder depending how much torque reduction is requested, the older LS1 PCM was all or nothing.

Bottom line is if you want TCS to function normally then don't mess with these tables on the E40.

There is another table in the traction control method system TCS method/ Min Desired Torque, and it reads:
Minimun TCS Desired Torque vs RPM: the minimum allowed torque for traction control limits, TCS can never command a lower torque than this.

Can we use this table to control the requested torque reduction initiated by the ABS Controller and effectively use TPS max as a throttle stop as suggested by 5_liter ?

[flea]

I'm wondering if the Active DC Min could also be adjusted. Appears to be set at 24% for LS2 vettes and GTOs. However, the value is higher on some of the Holden vehicles and I believe on the Trailblazer SS (40% I think). Might be a way to make TC more or less intrusive?

[flea]

Active DC Min
Trailblazer SS: 30%
Thunder Ute SS: 40%

Or maybe these differences relect different types of ABS and/or TC systems? My impression is that increasing these values would raise the threshold for the TC system to kick in.

[bluegoat06]

Well, i did some logging tonight, and i have some interesting results to share.
everything was done mostly in 1st gear. i'll be posting the results soon. i was able to see the TC and ETC TPS Max in action with the ETC TPS Max table and Spark Retard vs TQ reduction back to stock settings.

[bluegoat06]

first run
TM ON (stock ECT TPS MAx, Spark Retard vs Torque Reduction)
TC ON
1st gear WOT from 1600rpm, TCS not engaged, but TM Advance is showing up, 4.1* timing dips down to 17.5* from the 23* base spark.

[bluegoat06]

2nd run
TM ON (stock ECT TPS MAx, Spark Retard vs Torque Reduction)
TC ON
1st gear, WOT from 2700rpm, TCS kicks in, ETC TPS Max Kicks in effectively closing ETC
no TM advance, but the timing is drops

[bluegoat06]

TM ON (stock ECT TPS MAx, Spark Retard vs Torque Reduction)
TC OFF
1st gear WOT, ETC TPS Max doesn't Kick in, TCS doesn't Kick in, but TM advance is showing up, 6.3*

[bluegoat06]

TM ON (stock ECT TPS MAx, Spark Retard vs Torque Reduction)
TC OFF
1s gear wot, violent wheel hop, some KR showed up because of this, TM advance again 8.7*, No ETC TPS Max

[bluegoat06]

TM ON (stock ECT TPS MAx, Spark Retard vs Torque Reduction)
TC OFF
2nd run WOT from 2600rpm, TCS does't kick in, ETC TPS max doesn't kick in, TM advance shows up one more time, 4.9*

[bluegoat06]

TM OFF (ETC TPS max set to all 100's, Spark Retard vs Torque Reduction set to all zero's)
TC ON
2nd gear wot from 2700rpm, no signs of TM advance, no ETC TPS Max, timing doesn't drop from the 23* base.