Gearshift Maps
 

I've been looking at the TCU recently and have located the shift plan and figured out how to decode it. The shift plan is composed of multiple shift maps. There is one shift map for each possible combination of mode, stick position, and current gear. Each shift map is comprised of an upshift curve and a downshift curve.

As an example: The UK TCU has 6 modes (Normal, Economy, Power, Manual, Cruise and Overheat). There are 4 stick positions (D,3,2,1) and obviously 4 gears (1st,2nd,3rd,4th). Therefore there are 6x4x4=92 shift maps in the shift plan.

The shifting decision is based on vehicle speed and throttle, not rpm. This is confirmed by the factory service manual. Let me demonstrate how it works with the aid of the Normal-StickD-Gear2 map and the Normal-StickD-Gear3 map.

http://www.alcyone.org.uk/ssm/gearmap1.jpg

Suppose you are driving in Normal Mode, with the stick in D, at 50mph and 40% throttle. The gearbox is in 3rd gear. Imagine a dot at (50,40) on the 3rd gear map (the one on the right). If you floor the gas, the dot will move vertically up the chart. When you get to about 88% throttle, the dot crosses the downshift curve and the box changes down to 2nd gear.

Now the dot is on the 2nd gear map at 100% throttle and moving right as the speed increases. When you reach 85mph the dot crosses the upshift curve and the box changes up to 3rd gear.

That's the basic theory. Now lets look at some more pictures.

Here are the upshift and downshift curves for a USDM SVX in Normal mode, with the stick in D. I have superimposed the 4 maps into one diagram.

http://www.alcyone.org.uk/ssm/gearmap2.jpg

You will note that the gear1-downshift map is a horizonal line at 100% throttle, because obviously we can't downshift from 1st gear. Similarly, the gear4-upshift map is a horizonal line at 0% throttle because we can't upshift from 4th gear.

http://www.alcyone.org.uk/ssm/gearmap3.jpg

If you compare the Power mode curves you can see that in Power mode, the TCU upshifts at a higher speed, and needs less throttle push to trigger a downshift. At 60% throttle it will change from 2nd to 3rd at 64mph in Power mode compared to 43mph in Normal mode. If you squeeze the gas pedal at 50mph in 4th, Power mode will downshift at only 35% throttle whereas Normal mode requires 62%.

The USDM TCU is a little more complex than the UK version. It has 7 modes (Normal,Power,Manual,Cruise,LowPres1,LowPres2,Over heat) and therefore 7x4x4=112 maps. The LowPres1 mode is activated when the atmospheric pressure is low. The LowPres2 mode is activated when the atmospheric pressure is very low. The TCU uses power mode if the atmospheric pressure is very very low. I have no idea why Subaru would need different shift maps based on atmospheric pressure. Perhaps to compensate for reduced engine power at altitude? Only the USA model has this feature, the UK and JDM don't even have a pressure sensor.

Now for yet another answer to the FAQ "What does the manual button do?". Below are the maps for Manual Mode with the Stick in 3. You can see that the car will start in 2nd but then upshift to 3rd almost immediately and then hold 3rd right up to 143mph. On the downshift, it will hold 3rd all the way down to almost a standstill. When the stick in is 2 (not on this diagram), the car will start in 2 and hold it right up to 91mph. Essentially, Manual mode does its very best to keep you in the gear you have selected on the shifter.

http://www.alcyone.org.uk/ssm/gearmap4.jpg

The JDM model has only 5 modes (Normal, Power, Cruise, Manual and Overheat), however there is data for 2 extra maps that never seem to get used. I was expecting that the Normal and Power maps would be the same between JDM and UK models, but they are not. Here is a comparison of the upshift maps between the two models.

http://www.alcyone.org.uk/ssm/gearmap5.jpg

It appears to me that the UK Economy mode is slightly more relaxed than the JDM Normal Mode while the UK Normal Mode is slighly more aggressive than the JDM Normal Mode. ie. The JDM Normal mode is inbetween UK Economy and Normal. The UK Power mode is also more aggressive than the JDM Power mode. There is no point in comparing the USDM maps without some way to compensate for the different diff ratio.

I have extracted the maps into a big Excel spreadsheet attached to this post. So you can have a play with it if you are interested. To plot a graph, first select the tab for the version of car: UK, JDM, USDM. Select column A or B depending on whether you think in mph or km/h. Then hold CTRL and select additional columns for the maps that you want to include in the graph. As a first attempt, try columns C,E and G (Normal-StickD-Upshift maps for each gear). Then click on Insert/Chart. Select the "XY Scatter" chart. Click on the last icon "data points connected by lines without markers". Then Next/Next/Next and admire the pretty picture.

Having decoded the shift plan, I'm pretty confident that I could modify it and I'm already thinking about loading the UK power mode maps into one of my JDM cars. Plus, maybe an improved version of the as-yet-untested power mode mod for UK cars. But there's a few more things I need to figure out first, like the torque converter lockup for example.

Re: Gearshift Maps
 

I know I said there was no point, but actually it quite interesting to compare the UK, JDM and USDM models on the same chart.
http://www.alcyone.org.uk/ssm/gearmap6.jpg

Re: Gearshift Maps
 

So how far from being able to remap the TCU are you?

Re: Gearshift Maps
 

It depends what needs remapping. I could modify the gearshift maps now, but other stuff like the workings of the 4wd system I haven't figured out yet.

Re: Gearshift Maps
 

Think you could write a chip that eliminates the ECU inputs like we had talked about?? I am sure I could get TPS and RPM outputs from the Hydra as long as we have a place to input them

Tom

Re: Gearshift Maps
 

I would be interested in experimenting with this. :) Let me know what i need :)

Re: Gearshift Maps
 

Yes. Should be fairly straightforward. I'll start working on it.

Re: Gearshift Maps
 

OK. Here's a quick howto:

1. First you need to grab a spare TCU and modify it as per the instructions on my website. Unsolder the ROM chip and solder in a socket. If you aren't good at soldering, go find a TV repair shop. You are also going to need an eprom programmer and a blank eprom. A select monitor interface and some datalogging software would be useful for debugging your modified maps.

2. Then you need to download Nomake Wan's TCU file from my website. 1992 USDM model, RomID 705404. Or you can extract your own using my tcudump program.

3. Find the map you want to change:
Open the file in a hex editor and scroll down to address 0x0000CFAD. For those who don't know, writing 0x in front of a number indicates that it is a hexadecimal number. At address 0xCFAD is a list of 16 bit pointers to the maps. ie. It holds the start address of each map. The first map is at location 0xD16D, the second at 0xD17C, the third at 0xD17F etc.

Decide which map you want to modify and work out its position in the list:
Map Number=(Mode*32)+(Stick*8)+(Gear*2)+Direction
where:
Mode: Normal=0, Power=1, Manual=2, Cruise=3, LowPres1=4, LowPres2=5, Overheat=6.
Stick: PosD=0, Pos3=1, Pos2=2, Pos1=3
Gear: 1st=0, 2nd=1, 3rd=2, 4th=3
Direction: Upshift=0, Downshift=1

This should give you a Map number between 0 and 223 (decimal). The Pointer address is 0xCFAD + (Map Number * 2).
For example: The map for Power-Stick3-Gear2-Upshift: Map Number=(1*32)+(1*8)+(1*2)+0=42. Pointer Address=0xCFAD+(42*2) = 0xD001

Look in the list at address 0xD001 and you will see the address of the map is 0xD2E7. Now scroll down to 0xD2E7 and look at the map itself:

4. Here is how you decode the map:

Arrange the data into columns of three bytes like so, label them K, M and T
Convert them all to decimal and then subtract 128 from each number in column T.
K is a speed in km/h. The TCU will use the first row for speeds up to 40km/h, the second row for speeds up to 81km/h, the third for speeds up to 126km/h and so on.

T is a TPS signal between 0 and 127. Zero represents no thottle, 127 represents full throttle. In the previous posts I have converted this figure to a percentage.

The tricky bit, M is the gradient, in 16th's of the line running back from point (K,T) on the graph.

Expressed algebraically, the formula for the graph is: y=T-((M/16)*(K-x)).
where
x is the speed in km/h that you want to know the tps value for.
K,M and T are taken from the appropriate line of the table that corresponds to the speed x.
y is the tps value from 0 to 127.
http://www.alcyone.org.uk/ssm/gearmap7.jpg
As an example:
Suppose we want to know the tps value of the change point at 100km/h.
We use the third line of the table: x=100, K=126, M=24, T=112.
y=112-((24/16)*(126-100))=73
Converted to a percentage (73*100)/127)=57% thottle.

5. To modify the map, work out where you want the shift points to be, then work backwards through step 4 to find what the new values should be and update them in your hex editor.

6. Now use my checksum program to update the checksum in the modified TCU file. I'm pretty sure the TCU never checks this, but better safe than sorry.

7. Write the modified TCU file to an eprom chip and insert it into the socket on the TCU.

Re: Gearshift Maps
 

I have a ton of TCU's here if anyone needs a spare, pay shipping and its yours.

Tom

Re: Gearshift Maps
 

Awesome! I'm going to run this by my buddy who tunes my OBD1 stuff. Then I'll start making changes and provide updates as far as how I like it, ease, etc.

Hey tom, I'd be interested in a TCU. Let me know the deal :)

Re: Gearshift Maps
 

Not to keep posting lol, but are you thinking or trying to create a program to simplify this into a basic GUI program?

Re: Gearshift Maps
 

I have a program that I created to extract the maps from the TCU dump file into a CSV file that I used to create the Excel spreadsheet.

I am thinking about making some modified maps and I will probably write some software to help with building and testing them. It will be Linux or DOS though because I don't have experience at writing Windows software.

Re: Gearshift Maps
 

Like I said, shoot like $15 for shipping anywhere in the lower 48 and I will send you one

Tom

Re: Gearshift Maps
 

One further thing I should mention on this topic is the RPM limit. There is a RPM limit that forces an emergency upshift to save the mechanical bits from destruction.

This is at location 0xD881 though 0xD884 for 1st through 4th gears or alternatively 0xD885 through 0xD888 if the manual button is on. This is global and applies for all the different modes and maps.

Without manual button, the values are 5E 5E 5E FF.
With manual button, the values are 61 62 64 FF

I *guess* you multiply these numbers by approximately 70 to get rpm.

5E=6580
61=6790
62=6860
64=7000
FF=17850 (it can't upshift up from 4th)

Re: Gearshift Maps
 

Excellent. I really dont like windows all that much anyways lol...... Also im just looking to have the trans stay in 1-3 a little longer and have it downshift at a lower TPS reading

Tom PM me an address for sending a MO.

Re: Gearshift Maps
 

I've figured out the maps for the Torque Converter Lockup. I'll post the technical details of how to decode them on my website in due course.

There are 52 maps in total: 3 modes (Normal, Power, Overheat) multiplied by 4 stick positions ("D","3","2","1") multiplied by 4 gears ("1st","2nd","3rd","4th") makes 48 plus Cruise mode in 4 gears = 52 total.

Each map has a lock curve and an unlock curve. The TC will be locked when the speed rises above the lock curve and unlocked when the speed falls below the unlock curve. The x scale is tps and the y scale is speed. This is the opposite way around the the gear shift maps earlier in the thread. I have converted the scales to a percentage and mph for the picture below.

Most of the maps, for example 1st,2nd and 3rd gear are a straight horizonal line at 159mph. This effectively means "do not lockup the torque converter" because the car is unlikely to ever exceed 159mph in those gears.

If you look at the top left map in the picture below, this is Normal-StickD-Gear4. You can see at 50% throttle, the TC will lock as you accelerate past 77mph and unlock as you decelerate past 55mph. If you were drag racing at 100% throttle, it would lock at 92mph on the way up and unlock at 86mph on the way back down.

It has been mentioned in the "Power Mode Mod" thread that the TC does not lockup in power mode. This is not entirely true. As you can see from the top right map: In 4th gear, it will lock at 92mph and unlock at 86mph in any throttle position.

In the bottom left corner you can see the cruise map, the TC locks up at lower speed and lower throttle for smooth driving and economy.

Finally, in the bottom right corner is a sample of the overheat maps. When the TCU is in overheat mode, it locks up the TC even in 2nd and 3rd gear, not just 4th like the other modes. It has often been said that the TC generates a lot of heat. When the transmission gets too hot, the TCU locks it up whenever possible to try and stop the temperature from rising any further.

http://www.alcyone.org.uk/ssm/lockup1.jpg

These maps were taken from a 1992 USDM TCU.

Re: Gearshift Maps
 

good work,

I can supply the prototype and 94 tcu bins if you want them.

Re: Gearshift Maps
 

If people want I can supply socketed tcu's. I have a box of them. I don't want to sell them rediculously cheaply though...or be acused of charging too much either..so i don't know.

Re: Gearshift Maps
 

Thanks Mike. I find the TCU code a little easier to work with than the ECU. :)
Yeah. Thanks. Every little bit helps with the research.

I have the 92 and 94 JDM bins. I upgraded my 92 car to the 94 firmware just in case it helps the transmission last longer. I haven't analysed the differences yet :rolleyes:

I've just been looking at a Legacy TCU from 1990. It doesn't have any of the "overheat mode" processing. I suspect that Subaru may have added the overheat mode in an attempt to overcome transmission overheating problems with the early SVX prototypes.

Re: Gearshift Maps
 

Ya, I think you'll notice a few things in the first 5 minutes of looking at the late model code. i sent to the email on your website.

Re: Gearshift Maps
 

I have a Legacy Turbo TCU that I have yet to put in my wife's car (Previous owner swapped the TCU out when he put the non-turbo motor in it, thinking it was the ECU) I wish I had an EPROM programmer so I could dump the maps out of both of them and see if they are any different.

Re: Gearshift Maps
 

You don't need a eprom programmer for that.

You just need a cable to connect your car to your PC. Then you need a linux bootdisk and my tcudump program.

Re: Gearshift Maps
 

:eek: :lol:

I'm guessing this TCU (725606) uses a different CPU chip? Not very different, but different enough to break my 6811 disassembler. Maybe a 6816?

Is this from an OBD2 car?

Re: Gearshift Maps
 

No, that's the 94 usdm rom. Most if not all obd1 USDM awd SVXii use the e23aa11p or e23aa12p roms. That's the e23aa12p rom--the latter model obd1 rom. I used the Dewtronics M6811Dis v1.0 code seeking dissassembler back when I did it. Maybe you didn't notice it's sitting in a 32k ROM and your control file is loading it complete with padding to c000? May also need to edit some entry points?

Re: Gearshift Maps
 

I noticed the 16K of FF on the front. I am loading this image at 8000. I guess the bigger rom gives much more space for TCU mods. :D

Now that I have looked at it properly, I can see that the image you sent me is corrupt. Bit 1 of every single byte is set to 1. This obviously results in incorrect disassembly. I thought I was using the wrong disassember.:rolleyes:

Compare the following:

This is the 705402
This is the 725606
You can see it better in binary:
The whole image is corrupted like that, every single byte has that bit set to a 1. I can't imagine how it could have happened.

Re: Gearshift Maps
 

that would mean it's a 705404 bin. I'll look at my files and figure out what's going on. I labled that file yesterday off of the rom code so it happened at least before that. I thought that bin was the basecode I'm running in my car but I guess not. I have a good 94 bin here somewhere because it's the base of what I'm running in my black car; unfortunately I don't seem to have labled anything very well.

Re: Gearshift Maps
 

ya, sorry about that. It should be 705404. I think that bin I sent you yesterday was a read of a mis-solder I forgot to throw away. I remember I had to settle for soldering my surface mounts to a less than ideal adaptor that proved to be a pita to solder. I'm sending a good bin now.

Re: Gearshift Maps
 

OK Thanks. That one looks better.

You take the chips off the board to read them rather than using the select monitor port? That really must be a PITA. I find it impossible to unsolder them from the board without destroying them.

Re: Gearshift Maps
 

I'm pretty good at desoldering; I don't have any problems removing the surface mounts. I think your euro and jdm tcu's might not be coated but the usdm tcus are coated after assembly--that's really the annoying thing about socketing them. It costs a fortune in solvent getting them stripped before desoldering.

I guess now is a good time to give tips to anyone who's going to socket a US tcu. Don't even try desoldering/soldering until after you clean off the coating. Assuming you aren't experienced at desoldering, do what Phil does and cut the legs of the surface mount with an exacto knife instead of desoldering it (cut along the rom, not the pcb). If you do a clean job of cutting the legs you shouldn't even have to desolder them. You still have to clean the coating off of the through holes for the dip chip before you can empty them and solder in the socket.

Re: Gearshift Maps
 

phil,

just in case you want independent verification of addresses here are my main svx specific labels

label 1044 VB
label 0019 VSP1
label 001A VSP2
label 00B6 EREV
label 0017 ATFT
label 1040 THV
label 004E GEAR
label 00B3 PLDTY
label 00B4 LUDTY
label 00B5 4WDTY
label 1046 BAROP
label 0011 BITFA0
label 0012 BITFA1
label 0013 BITFA2
label 0014 BITFA3
label 0001 DIAGU1
label 0005 DIAGU2
label 0003 DIAGM1
label 0004 DIAGM2

label 0018 VSpeed

Re: Gearshift Maps
 

705404 is the 92 ROM isn't it? I don't think I'm finding the right file for the 94. I'll just read it again.

Re: Gearshift Maps
 

I just use a 0.8 mm pin drill, to drill through the solder holes for the socket. Saves heating the board too much while you suck the solder out.:)

Harvey.

Re: Gearshift Maps
 

The euro and jdm ones are coated too. I haven't used solvent on mine. Just melted it with the soldering iron and scraped off the residue. Then take off any remaining solder with copper braid and polish with a fibreglass pencil. It looks shoddy but it works.

Solvent would be a better way to do it, but I didn't know at the time.

Re: Gearshift Maps
 

Thanks for confirming the addresses. They match exactly with my list and the one from Tom's select monitor.

Yes. I just checked and your 705404 is the same as the one from Nomake Wan's 1992 car.

Re: Gearshift Maps
 

Phil what are you doing with your shift maps? Do you have any engine work deserving of higher revs?

I'm a big fan of making the 2 to 1 shift come in with less throttle and raising the shift points/rev limits. I haven't really found anyting else in the shift maps I care to change. Even in a stock SVX I find changing the 2 to 1 downshift map a huge improvement though. I can't imagine anyone not wanting to.

Re: Gearshift Maps
 

I find the JDM box pretty much perfect, I don't really plan to change anything except perhaps to lower the temperature that the overheat mode kicks in. My engine is completely stock and my ECU and TCU are running the standard JDM maps.

What you suggest about the 2 to 1 downshift sounds interesting. I drive with the power button on nearly all the time. But I have noticed that when pulling away from a slow roll, it is often better to be in 2nd than 1st. The engine has plenty of torque available. Is that what you are talking about?

I have done a mod for the UK models to change the econ mode switch to a power mode switch. A few people have that now but nobody has tested it yet.

Other than that, I've been talking to a guy about doing one optimised for cars with the 4.44 or 4.11 diff swap. Somebody else is talking about swapping the internal gears in their box and wants a custom TCU for that. But I'm not working on either of these things yet.

I am planning to do a version of the USDM TCU that doesn't require signals from the ECU. It can be used with the standalone ECU that Tom is working on.

I do want to try the paddleshift code just to see it working. I wouldn't want to keep it on my car permanently.

Re: Gearshift Maps
 

Phil I perfer the shift maps on the JDM TCU. I found I drove most of the summer with the power switch turned on my JDM car. Really only switching to compare the two modes

I have done the power mod switch on my Canadian SVX and found while it is great in that it feels very sporty it holds each gear too long under lighter throttle. I find myself constantly turning power mod off and on.

If I had a choice I would have JDM power as normal mode and USDM (Canadian) power mode mapping for the power mode switch.

Peter

Re: Gearshift Maps
 

kind of,

I was mainly talking about the downshift of the normal mode map but yes I also like to change the normal mode upshift map into a kind of a hybrid betwen the normal and power mode map.

Re: Gearshift Maps
 

Thanks to Phil :) if you like playing with electronics you do have a choice. You don't have to know anything really about computers or software to do what you want. That's a simple copy from one map and paste in the other map kind of thing.

Re: Gearshift Maps
 

Phil, did you notice full throttle shifts are off the rev limiter not the map?