Pro racer - shift schedule

[JoeBoomz]

I'll do this in multiple parts because there's lots to type. Also the non-interested parties can just skip the preface and get to post 2 for the details

Recently I ordered the SCT Pro Racer Package from Mr. Dennis Reinhart so that I could tune my Marauder to my liking. One of the first things I wanted to address was my shift schedule. My MM is a summer daily driver so I have had lots of great opportunity driving to/from work to tweak these settings.

I don't know if a lot of people feel the same as I do about this, but I HATE cruising along at a higher RPM than necessary. As a very basic example, cruising at 2,000 RPM in 2nd instead of 1,250 RPM in 3rd. To solve this while driving, I would have to speed up then take the foot off the gas to force an upshift to get the engine to a lower RPM, then slow back down to speed (where it would maintain that gear). This is something I wanted to address in tuning.

Secondly, I HATED the downshift schedule. When I hammer the pedal, I want my car to shift down to something aggressive. NOT just down one gear to 3000 RPM. While this was fine for my Grand Marquis, the Marauder should be more ballsy. This is something I wanted to address in tuning.

Third, the upper RPM on shifts. If I recall, stock does it around 5500 RPM. BOOOOOORRRRRRRIIIIIIINNNNNNG. Jack this baby up to 6500 and you'll really start having fun. This is is something I wanted to address in tuning.

Last reason - I bought my Marauder used; the original owner had Dennis' Level 2 Transmission kit (ArtCarr) and JMOD installed, resulting in VERY firm shifts. 1-2 especially. What this means is that at 1-2 WOT, I ALWAYS get wheelspin. At higher RPMs, sometimes over 2 seconds of wheelspin before the tires grab again. However, at lower throttle positions, the tires would grab right away and the car would THUNK, or JERK. Very annoying. Even at light throttle, starting at the lights, it would accelerate to ~2,500 RPM then JERK into 2nd. Sometimes to avoid the embarrassment with passengers in the car, I'd start out in 2nd. This is something I wanted to address in tuning. Let me preface this by saying I have already reduced the shift pressures to their minimums without solving the problem. I found that the problem is fixable in the shift schedule, though.

Continued on Post 2...

[JoeBoomz]

...continued from Post 1

SCT Advantage III (the Pro Racer software) defines the shift schedule using Speed in MPH and Relative TP (Throttle Position). I posted more details regarding TP's HERE.

Here's what the screen looks like where you define the 1-2 shift (this is the stock 1-2 shift schedule for processor code JHM1):



The software locks the top and bottom TP values at 1020 and 0. I'm assuming these are the max/min values that the computer will process for this purpose. Initially, I could not figure out why my shift in the top row was never happening. What I realized is that your car may not reach this TP value. I will post about TP values separately - read there for further understanding of TP_ABSOLUTE and TP_RELATIVE. The shift schedule uses TP_RELATIVE. I posted more details regarding TP's HERE.

It is important to consider this - you can change the table to "focus" on certain TP ranges more than others. For example, your TP rows could be 1020, 900, 750, 600, 500, 400, 300, 250, 200, 0, which would allow you a more granular control over the shift points at lower throttle, where you spend more time.

It's hard to get an idea of how this all works without graphing it out. Luckily, the team at SCT provided built-in graphing in Advantage III. Here's the graphical representation of the stock shifting schedule.



When I first saw this I said WTF?! Now I know why it's so freaking hard to predict the shifts in my car! What a mess!

First we take a step back and think "maybe they do this for a reason, to maximize the use of the engine's peak torque and efficiency at certain RPM's." Then I remember that when I'm cruising along at 3,000 RPM I have to speed up to force an upshift to slow the engine down and decide "NAH. There was no plan."

Continued on Post 3...

[JoeBoomz]

...continued from Post 2

My first goal was to build a schedule that was predictable. So that me (the driver) could actually CONTROL the shifting in my car via the gas pedal.

Aside from not shifting at all, the next most predictable setup would be a straight-line TP to MPH shift schedule. Here it is:



In testing, this actually works VERY WELL. Not PERFECT, but I think better than stock. This schedule shifts at 6000 in the top end, and the downshifts will occur up until the downshift results in an RPM higher than 5500. This means that when I hammer the pedal in 2nd or 3rd, it will go to 1st if the resulting RPM is lower than 5,500 RPM. The most aggressive scenario is a downshift to 1st to 5,500 RPM, accelerate to 6,000 RPM, and then shift back into 2nd (with accompanying wheelspin if at WOT).

One other cool feature about the above schedule is that if you keep your foot on the gas pedal in the same position, ALL of the shifts occur at the SAME RPM. So if you're down a third of the way and don't move the pedal while accelerating, 1-2, 2-3 and 3-4 all would happen at ~3,500 RPM, as an example. So if you start out light on the gas the car is very polite and has manners like a Lincoln Towncar - it upshifts quickly and keeps the RPM's down and the engine quiet. If your foot is on the floor it behaves like a Marauder should.

This is a good time to bring up another very important point - SHIFT LINES CANNOT CROSS. The 1-2 shift line cannot cross the 2-1 shift line. If it does, your transmission will freak out and shift back and forth rapidly. The Advantage III software warns about this and I didn't try it to confirm it. I makes perfect sense to me and I'll take their word for it.

How did I fix my 1-2 JERK issue? Easy, the 1-2 shift occurs at very low speeds at lower TP's, before we've got enough power to cause a JERK. It's similar to starting out in 2nd, but automatic. If I'm WOT, it stays in 1st up to 6,000 RPM. "Why not 6,500 Joe?" you ask? I get too much wheelspin then!!!

To figure out the lines and slopes, I had to dust off the old formulas I learned in school. Well technically, I Googled them, but it came back clear as day.

A straight line has the formula y = mx + b, where m is the slope and b is an offset. How to calculate m and b?



So to build the shift lines, you figure out the top speed you want in the gear, the bottom speed you want in the gear, and at which TP's you want the shifts to occur. This gives you a set of (x,y) coordinates that you can use the formulas to calculate the rest.

Here's the 1-2 shift table for a linear shift schedule (this one does have a 6,500 RPM shift):



*IMPORTANT* Notice the TP column is "cleaned up" compared to the stock table in post 2 - because your TP_RELATIVE positions will focus more heavily on lower TP values, you may not want to use the TP scale shown here as a jump from 0-200 TP misses a lot of different (and important!) throttle positions encountered during non-WOT driving.


Speaking of lines, here's something important to realize that follows from the granular TP discussion above. With a straight line, you only need two points. Consider the following two graphs:





The bottom graph accomplishes in 4 points what the top one does with 10. The computer in the car will use the nearest points on the graph to where you actually are in the TP/MPH calculation to calculate the slope and determine if it should shift or not. So if you're working with a straight line, two points will cover it.


I'll repeat myself here in that I found that the straight line solution wasn't perfect. I found driving like this for about a week that sometimes the downshifts came too easily. Also, I would have also liked it to rev a bit higher before shifting in many cases.

The next step was to build some shifting curves to accommodate these needs.

Continued on Post 4...

[RacerX]

Hey Joe! Nice work BTW! SCT forums are like a ghost town...
Raise your RPM based scalars too.

Here's a couple of 1-2 schedules I've used:

[JoeBoomz]

...continued from Post 3

Dammit Bill, you had to get a word in edgewise, didn't you? You're right though I did get hung up on the scalars limiting the shift RPM's as well. You need to jack these up to match or exceed what your shift schedule is set to, otherwise your shifts will occur early. For everyone else, here's what that screen looks like:



I decided to post this here instead of the SCT forum because I'm sure there are a few Marauder owners that might consider PRP after seeing some of what it can do for their car! Also, the data then applies to them.



So I needed downshifts to occur at higher throttle positions, and upshifts to occur later than they were. Straight lines weren't going to cut it. At this point things get a bit more nerdy, so DOOM and CBT, I won't mind you guys check out to go drool over some more DTR's.

Let's start with some pictures to illustrate what the end result needs to look like:





First, I fired up Google again, planning on working with some hardcore 2nd and 3rd degree polynomial functions to draw me some sexy curves. Then I realized, "hey, we're working with 10 points with straight lines between them." So I went back to the straight line formulas.

To start, I figured out what sort of slope I wanted between the 200-300 TP positions.

On an upshift, a tall slope (greater than 1) is required so you don't shift right away into the next gear while accelerating if you have the pedal down.

For downshift, a small slope (less than 1) allows the vehicle to maintain the gear at lower TP's, and only command a shift when you put the pedal down.

I used Excel to build out some template worksheets to calculate the slope required between each point to start out a target MPH at low TP and finish at the desired target MPH at the high TP. The sheet, using Excel's Goal Seek function, calculates the points based on the provided slope.

Here's the 2-3 shift slope calculations:


1. Specify the slope divider per step (how much the slope will be divided by between each TP). This makes your curve more or less aggressive. Slope divider of 1 builds a straight line, whereas > 1 builds a "convex" upwards slope and < 1 builds a "concave" upwards slope slope.

2. Figure out your desired bottom MPH value (at TP 200). Then use Goal Seek to find the first slope (in blue) required to get to your desired top MPH value.

Here's the 3-2 shift slope calculations:



The resulting 2-3 3-2 shift curves feel much more "natural" to drive than the linear schedule does - you have more room to move the pedal around before a shift will be commanded, however you still have perfect control over upshifting (let off the gas) or downshifting (put it down).

Continued in Post 5...

[JoeBoomz]

...continued from Post 4

In the end, after tweaking the curves I think I've found the schedule that works "perfectly" for me. It is still quite predictable, but it allows a decent amount of movement of the pedal before a shift is commanded. Here are some of the features:

- 1-2 upshift happens instantly at lower TP to fix my JERK issue. Put the pedal down however and it'll go up to 6K before shifting
- 3-4 upshift happens at higher RPM's at lower TP's. I found that, in traffic, the car would move into 4 and then I would downshift back to 3rd as soon as I needed to move around someone. Bringing the 3-4 upshift to a higher RPM has alleviated this and 4 only kicks in now when I'm cruising at higher speeds. See also: OD disable button
- Downshifts are more aggressive - the car will go to the lowest gear that it can up to 5,500 RPM.


I have played with two different variations on the shift curves now. The first has "concave" downshift curves:

The big difference with this set up is that you won't command an downshift at only partial throttle. You always have to put it down to make the car shift.

After a few weeks of driving this daily, I missed having downshift happen at part throttle. So I started playing some more and here's what I'm using now:

Here's another version, with "convex" downshift curves:

Downshifts in this schedule are more aggressive than the one above. A downshift will be commanded at part throttle now - not enough to be annoying like the linear shift schedule, but it makes for a very fun driving experience.


For further reading, I have posted further about shift schedules and TP values HERE. Let me know if you have any questions!

[LANDY]

good info here guys, keep them coming.

[Michael]

Excellent information. Thanks

[justbob]

Sounds nerdy I love it. Keep it coming, been wanting to look into this for quite sometime.

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[sailsmen]

Good information. Thanks for the write up.

Go to the track and see how your shifts are.

I have used the Pro Racer software to get the shifts dead on where I wanted them making adjustments at the track as well as dowloading different tunes emailed from my tuner while at the track.

You can also adjust the TC lock up schedule.

[JoeBoomz]

Good information. Thanks for the write up.

Go to the track and see how your shifts are.

I have used the Pro Racer software to get the shifts dead on where I wanted them making adjustments at the track as well as dowloading different tunes emailed from my tuner while at the track.

You can also adjust the TC lock up schedule.

I don't take my car to the track, but if I DID, I would use the fully linear schedule that lets you control at which RPM's the shifts occur by keeping the pedal in a certain position at all times.

For track usage, are you not always at WOT anyway?

[Svashtar]

This is outstanding work. Really nice research and write up, thank you. I have to say though I feel like a total dumba$$, because I don't think I could duplicate your analysis in a month of reviewing it! (I understand the Excel stuff, but that's about it. )

I have an old SCT Tuner from DR, I think it was the 9100? .cex files, and the tuner and download cable was 5 bills. After the tranny rebuild and PI 3000 install the 1-2 shifts are brutal, and I honestly hate the kick in the butt jerk when just taking off from a stop light in normal traffic.

I recently switched back to the factory tune in order to get my '03 smogged for just the second time. I had to run it for a week before my ScanGauge showed "Ready" (all internal diagnostics had completed successfully). One night I took it around to a private track and I _could not believe_ the acceleration at WOT. It was like a whole other car with the stock tune! The full art carr rebuild actually feels like it slowed the car down when coupled with the original '04 tune. I have no idea why.

I know it's not logical, but aside from the lousy TC handling at slow speeds, the stock tune actually feels faster, at least SOP feel, and especially at WOT. (It's sloppy at slower speeds though with the much looser converter.) And the mileage went up from 15 to nearly 19 mpg. If I could just leave it alone and tweak it to recognize the 3000 stall and the 4:10's I think I just might do it.

Here's something I've never been able to explain (after the full trans mod): DR tune, WOT, then take your foot off the gas, car slows quickly; stock tune, WOT, then take your foot off the gas, and you are still _moving_. It takes a much longer time to slow the car. The variable has to be the tighter tranny.

If I had half your knowledge I would try to tweak mine to just lower the RPM's a bit and make the same shift adjustments you're doing.

Anyway, I have hopes that someday I'll be able to get it properly tuned. There has to be a compromise between the stock tune and a full out race tune. Mine is a 30 mile per day daily driver, but I want it to go when I stomp on it.

Thanks again.

Norm

[TooManyFords]

Here's something I've never been able to explain (after the full trans mod): DR tune, WOT, then take your foot off the gas, car slows quickly; stock tune, WOT, then take your foot off the gas, and you are still _moving_. It takes a much longer time to slow the car. The variable has to be the tighter tranny.

There is a setting in the tune whether or not to release the lock on the converter when decelerating. I suspect DR has tweaked that to not release.

I'm sure it is a preference sort of thing, and one I do not use myself.

[Blackened300a]

Here's something I've never been able to explain (after the full trans mod): DR tune, WOT, then take your foot off the gas, car slows quickly; stock tune, WOT, then take your foot off the gas, and you are still _moving_. It takes a much longer time to slow the car. The variable has to be the tighter tranny.

My tuner had my trans unlocking the convertor everytime I took my foot off the gas at highway speeds. With a stock convertor it wouldn't be too noticable, with my 3K stall it was irritating. I would let off the gas, the car would coast, then I would step on the gas and the RPMS would flare up then the convertor would lock. I called him up and he tuned that out so the convertor will stay locked above 45MPH. This also helped me slow down by just just taking my foot off the gas and not hitting the brakes.

[justbob]

My converter is fully locked out to 65 MPH under light load and will unlock with OD off, 1/4 throttle or so, or will unlock itself if coasting down to 35 (typical off ramp speed). LOVE IT. OD is set to not come on to 53 MPH (typical speed limit around me is 45 and lower) Thanks a million Zack!
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