Pro Racer - TP Absolute and TP Relative

[JoeBoomz]

Many tables in Pro Racer use TP as one of the axis and I wanted to post this here to save anyone new to Pro Racer and LiveLink a LOT of time.


LiveLink from SCT allows you to datalog your car while it is running, and two of the PID's that are available for logging relate to Throttle Position. They are called TP_ABSOLUTE and TP_RELATIVE.

I did some basic testing when I started using Pro Racer and incorrectly assumed that the TP that was referenced in these tables was TP_ABSOLUTE. This is wrong, and I have since re-tested and confirmed that TP_RELATIVE is the value used in Advantage III tuning tables. It turns out that TP_RELATIVE is a "learned" value based on TP_ABSOLUTE.

My shift schedule and TC lock posts have been updated to refer to TP_RELATIVE instead of TP_ABSOLUTE.


I found this old post by mach1_cal_man on the SCTFLASH forum from June 2007:

You typically use tp_rel in Ford-speak. This is the absolute TP value - ratch. Ratch is the learned offset of the closed throttle body which varies a bit over time and car-to-car, but the differences are small. The strategy uses tp_rel for most throttle position related functions and maps.

So how do the two compare to each other? I took about 60 minutes' worth of datalogging in mixed city/highway driving and compared the average of TP_RELATIVE to different TP_ABSOLUTE values:



I love looking at data like this almost as much as RacerX likes to dremel stuff!!! The leftmost column shows how many lines in the datalog had the corresponding TP_ABSOLUTE (+/- 25). The rightmost column shows the AVERAGE of the TP_RELATIVE data for the corresponding TP_ABSOLUTE (+/- 25). As you can see, most of the time driving is spent with a TP_RELATIVE under 100. This is VERY important to consider when building out your TP-related tables!

My next step was to try to define "scenarios" for different TP_RELATIVE positions. After looking through several logs and taking notes, I have summarized the following for my Marauder:



(other cars may vary, as TP_RELATIVE values are learned by the ECU)

NOTE - the highest TP_RELATIVE I saw in my logs was 750. This is an important observation as many scalars in Advantage III involve WOT and you need to know what numbers will actually apply. Some of these settings come pre-set at 900, which is obviously too high!


So what have we accomplished with this scenario breakdown? Because Shift Schedules and TC Lockup schedules are TP-based, you enjoy very good control over when these events occur. Following are some examples.

Continued on Post 2...

[JoeBoomz]

...Continued from Post 1


I posted about my very harsh 1-2 shift due to the JMOD and ArtCarr transmission kit, and that one solution is to have the 1-2 shift occur early at lower throttle positions to avoid the JERK.

Using the above table of scenarios, it is easy to shift to 2nd as soon as possible at lower TP's. Here's what it looks like:






4th gear is great when you're cruising, but it isn't the best when you're dodging around in traffic. Using the TP scenarios above, you can set up your 3-4 shift so that it occurs earlier when you aren't hard on the gas (or decelerating) but will not occur if you are driving a bit more aggressively.






I also posted before about the TC lockup and associated BOG (drop) in RPM's. Using the above TP schedule, I was able to build out an enhanced 4th lockup schedule which will only lock the converter in 4th when you are at a very light cruise, greatly minimizing the drop in RPM's.






What other TP-related settings are there? Here are a few:

TP Above to Disable AC at WOT - this is "cool" if used at a setting like 500
TP Below to Enable AC After WOT- when to re-enable AC after a WOT run - 300
TP for WOT - stock settings have this at 800! As shown above, does this actually happen???
Max TP to Allow Learning - If you don't want the ECU to learn fuel correction above certain TP's this is your setting
Alternator WOT Cutout TP - Mine is set to 600
Alternator WOT Turnon TP - 500
Throttle Position to Not Unlock W Brake - use this to turn off TC unlock when braking, if you wanted
Throttle Position to Open Conv at Closed Throttle - mine is set to "6" but you might be able to tweak this to control unlocking at other throttle positions, unrelated to your vehicle speed


Oh, and one more important one - Trans TV pressures (shift pressures) are also TP-based:

*note my shift kit makes a very hard 1-2 shift, so my pressures are greatly reduced. Stock transmissions can run a 99-120 1-2 shift pressure with great results.

I haven't gone as far as to redefine the TP (X)-axis on the TV tables for the different scenarios, but if you want to get picky about shift pressures at different TP's, it's entirely possible.


I'll add more here as I find more uses for the specific TP scenarios.