850Ci M73 Steptronic M Gate - Upgrade to M/S Gate - Sport Drive Mode - DONE Wonderful

[m6bigdog]

It has been 18 yrs. since I purchased my 1997 850Ci.
I’ve spent those 18 yrs. searching for the “HOW TO” upgrade the Manual Shift-Gate Steptronic into the M/S Sport Drive Shift-Gate Steptronic.

So, Now I know “HOW TO”!!
I implemented the Steptronic Sport Drive with a BMW OE GS9.22.1 TCM and a replacement EPROM that has the identical Texas Instruments device spec.

IMHO, this is the most functional performance upgrade for the 850Ci M73 5-Speed since I upgraded to a 3.23:1 LSD.

Sport Drive Shift-Gate Steptronic:
There are two distinct differences between the M/S Shift-Gate and M Shift-Gate Steptronic.

1. When the shifter is tilted from D into the Shift-Gate the IC will display **SD** (Sport Drive) and the transmission will use a Sport Shift program where automatic up/down gear changes occur at a higher more aggressive RPM.
2. After tilting the shifter into Shift-Gate the shifter must then be tapped + or – to exit SD mode and activate the Manual Shift mode, where gear selection M1-M5 are available.
3. Once the Manual Shift Mode has been activated the shifter must be returned to the D position and tilted back into the Shift-Gate to reengage SD.

**Updates - 12/12/22**
After installing the SD TCM in a MY:1/95, 850-M73 the Instrument Cluster EGS Display did not show SD when the shifter was tilted, however, the “D” remains in the EGS display while in Sports Mode.
This did not affect the performance of the SD TCM.
It is assumed this is due to an early EKM HW: 6, module that does not have the hardware configuration to display the “S” letter while in Sports mode. EKM HW: 7, SW 9.8 version is known to work correctly.

So, What I know?

1. SD Programmed EPROM’s replaces the Manual Mode EPROM in the GS9.22.1 TCM.
2. There are two Sport Drive programs, based on the final drive ratio, stock 2.81:1 or 3.15:1. I have tested both SD programs and I’m undecided which I prefer! More testing needed!!
3. The 2.81:1 SD Program is a Sport+ program with automatic 1-4 gear changes with 5th available by tapping the shifter + to M5 or tilting the shifter into the D position.
4. The 3.15:1 SD Program provides automatic 1-5 gear changes.
5. I anticipate a future SD program with an even shorter final drive gear ratio. Details to follow.
6. Completed - 1/25/23 - Work to confirm the compatibility between the various GS9.22.1 TCM’s. 5 TCM modules verified - BMW P/N's: 1 422 253, 1 422 480, 1 422 866, 1 422 870 & 1 423 200
7. Completed - Hence, an SD programmed EPROM can be installed in a spare TCM and the Original TCM does not need to be sacrificed to have the Sports Drive

UPDATE - 10/25/22:
I did a TCM "Hydraulic Pressure Adaption - Reset" with my DIS and was driving around to evaluate the shift quality while the adaption updated and in D Position my 850-M73 was starting off in 1st gear. This was an unexpected surprise.
Update - 11-23-22:
RE: Reply 47, for more detail on D-Position 1-2 Kick-Fast shift profile...
The 1-2 gear changes in D Position occur at much lower RPM.
Update - 12-12-22:
RE: 850-M73 Steptronic M/S Shift Pattern overlay - DIY upgrade to go with the SD TCM
https://www.bimmerforums.com/forum/s...ith-the-SD-TCM
Instead of trying to locate the Unobtanium - 840-M62 Steptronic Trim
Also, could this inspire the +/- Manual Mode shift pattern reversal?
With the correct tools it is easy enough to simply swap the 2 pins in the connector.
E39 Late Model Steptronic replacement shift pattern +/- reversal.
See image of the replacement Shift pattern below...

*******
See Attached Files: BMW Technical Training Manual (03/98) descriptions.

I anticipate the next question will be…“HOW TO - GET IT”?

1. See post in forums "Parts for Sale" section. There are 363 850C1 with M73 & 5HP30. https://www.bimmerforums.com/forum/s...rogram-Finally
2. no longer needed: I would like a BimmerForum friend living in the SF Bay Area and interested in the SD upgrade to PM me.
3. (8 each, SD-TCM's installed and performing as anticipated, 1/25/23 - Evaluation no longer needed) I have upgraded several non-E31 GS9.22.1 TCM’s with the 2.81 and 3.15 SD Programs, available for evaluation.

[E36Ron]

This is great news!

From what I can understand, even though the BMW Technical Training Manual (03/98, US Edition) specifies the SD behavior you describe, none of the 363 US M73 cars actually came with this implemented. (I guess this was a Euro-only feature?)

So it will be great to have access to this behavior, which I believe was also standard on the M73 E38 cars.

We all look forward to further updates on this development!

-- E36Ron

[rjjablo]

Will it actually utilize first Gear?

[m6bigdog]

Will it actually utilize first Gear?

YES! YES! YES! It is Wonderful!!!!!

However, this EPROM Upgrade is only for the 850Ci with M73 & 5HP30 5-speed.

SD Shift-Gate, automatic gear changes from stand-still start-off in 1st gear. always.
Manual mode, M1 is available as long as the down-shift is plausible.
This is the Real Deal..
Read the POST attached documents.

[Hyper]

For newbies: the late 840 steptronic has the full sport function as per previous threads.

[Auraraptor]

This is Amazing! PM soon

[m6bigdog]

This is great news!

From what I can understand, even though the BMW Technical Training Manual (03/98, US Edition) specifies the SD behavior you describe, none of the 363 US M73 cars actually came with this implemented. (I guess this was a Euro-only feature?)

So it will be great to have access to this behavior, which I believe was also standard on the M73 E38 cars.

We all look forward to further updates on this development!

-- E36Ron

The Technical Training Manual SD descriptions Posted is for 840-M62 and 1999 740i/IL M62-Sport.
I owned a 1998-740i M62 (MY 4/98) and Steptronic shifter was not available yet but if I put the shifter in 4th gear the SD program was active with the GS8.60 TCM.
Also,
the early E38-M73 750i/iL had the same GS9.22.1 TCM as the E31 - Manual Mode and when the M73 E38's came out with an SD Steptronic (My first attempt to get SD Programmed TCM for my 850Ci, in 2010). Unfortunately, these GS9.22.1 don't work in the US or Euro M73 E31. All you get is a Trans Fail.

With that, the very limited production (World 1281 cars) M73 850Ci has been in existence for something like 28 yrs.
No professional tuner has offered an upgraded TCM EPROM for the M73 850 and only one other individual in 2013, offered a modified TCM EPROM for the 850 M73 and they have since gone silent.

FWIW,
I was in the Electronic Engineering profession for 40+ yrs and my knowledge tells me what approach to use for success.
Anyone that has read my posts and replies on E31 suspension engineering & tuning know I am serious about vehicle engineering.
While less engineering was required, I have applied the same due-diligence to the SD Program TCM upgrade.

I recently purchased 10 each GS9.22.1 TCMs from other BMW Series vehicles to test the compatibility with the E31 & SD EPROM.
Without harvesting quality used TCMs from the other more popular BMW Series the E31 community would need to consume the limited number of OE E31 TCM for EPROM transplant.
The issue is, should the TCM or the EPROM become damaged attempting to upgrade the TCM you will need another rare TCM and when the supply is limited for a rare commodity the acquisition becomes more difficult and/or more expensive.

I have decided to offer the various SD Programmed EPROMS in a sealed TCM as a Plug and Play Module for the M73 E31.
Installing an upgraded and tested SD Programmed TCM takes a few minutes and the evidence of success is almost immediate and should things go wrong, you have the option to immediately switch back to the original E31 TCM to support troubleshooting and fault isolation.
This way, I can support and protect the buyer and success is virtually guaranteed with minimal effort.
Releasing EPROM's only has none these advantages for the installer and a whole host of issues, I won't have control over.
Unsure if I will ever release the EPROM only.

Too Many Words, I Know...
More soon

[m6bigdog]

More details on the SD Shift Profiles.

I recently did 300 mile drive, SF Bay Area through the mountain roads to Yosemite, with the SD -Program 2.81 TCM.
What fun..

Note:
SD Program differences, automatic 1-4 or 1-5 gear change option.
IMHO, SD-2.81 with 4th gear hold has an advantage for sub 55 MPH driving with easy 1 touch in/out of OD.
With a 3.23:1 LSD, 55 MPH @ 2500 RPMs in 4th gear.
Still don't know which one is best!


SD-Program - 2.81 Driving Profile:

1. D Position – AGS with 2-5 gear changes, 1^st gear available with aggressive throttle application and/or WOT down shift.
2. SD Position – 1-4 sport mode automatic gear changes. (4^th gear hold - OD blocked)
3. OD – Tilt shifter from SD into D position. Automatic Up shift at RPM Limit (not tested).
4. SD 1-4 Resume – Tilt shifter from D position into SD.
5. M5 – SD Position, Tap shifter up (+) into M5 - Manual Mode active.
6. Manual Mode Active – M1-M5 Tapping shifter +/- to select M-gear within RPM Limit
7. SD 1-4 Resume – Manual Mode Active, Tilt shifter into D Position then back to SD.

SD-Program - 3.15 Driving Profile:

1. D Position – AGS with 2-5 gear changes, 1^st gear available with aggressive throttle application and/or WOT down shift.
2. SD Position – 1-5 sport mode automatic gear changes. (OD included in SD)
3. M4 – SD Position, Tap shifter back (-) into M4 – Manual Mode active.
4. Manual Mode Active – M1-M5 Tapping shifter +/- to select M-gear within RPM Limit
5. SD 1-5 Resume - Manual Mode Active, Tilt shifter into D Position then back to SD.

[Timm]

Excellent work, someone has done it at last!

[E36Ron]

Rod:

For completeness, and to have everything in one place, can you edit your shift profile post above to append the stock profile in the same format?

-- Ron

[Auraraptor]

Wonderful development and IMHO the best in nearly half a decade for the E31.

I am excited to try it out on my car.

[LappingLuke]

Making me want to add an M73 car to the garage just to try it out

[m6bigdog]

Post Updates:
I added a couple Instrument Cluster images to Post #1

Also, “HOW TO - GET IT”, See post in forum "Parts for Sale" section.

I shipped 4 of the SD Programmed TCM's to forum members, weather permitting, the feedback should start coming in soon.

[Auraraptor]

http://www.e38.org/electran1.pdf

Very exciting.

I am traveling right now but should have feedback hopefully soon as I get back.

Any tips on swapping the unit itself?

[m6bigdog]

http://www.e38.org/electran1.pdf

Very exciting.

I am traveling right now but should have feedback hopefully soon as I get back.

Any tips on swapping the unit itself?

Tips, why of course!
First and most importantly!!!!
Once you get the SD TCM installed and the adaption is performed, be careful, you just unleashed the beast in the M73.
I remember on one of my first test drives, on an on-ramp with an "S" turn, (thinking after 18 years of tuning my 850) man, I have never felt this before!!!
Then it came to mind, I know why BMW never put a Sports Drive TCM in the 850 with the 5--speed... YES, this could be dangerous!!
Definitely, take it easy in SD, until you understand what you are dealing with and what you just did to your gentleman's coupe!!
Also, if you don't have a Cargo Net now is a good time to get one!!
1st gear takeoffs can be exhilarating.

Now for the installation:
Remove the interior trunk panel on the driver side (left battery) and disconnect the both Battery ground cables (one nut).
Remove the interior trunk panel on the passenger side (right battery) and R&R the TCM.
Reconnect the battery Ground cables.
Leave the trunk interior covers off until you are satisficed that the SD TCM is performing normally.
Turn the key to position 2 without starting the engine.
Press the brake pedal.
Go through the gears, P-D-, tilt the shifter into SD ("M" Position), observe the instrument cluster display.
Now start the engine,
Press the brake pedal firmly and go through the gears, P-D, tilt the shifter into SD, tap the shifter back into M1 then tap forward M2-M5.
Observe the engine torque on the chassis as you shift through the gears R-N-D-SD Positions.
If the check went well, it is time for a test drive.
Start-out-slow, light throttle and test the shift quality.
If you notice anything out of the ordinary, other than the increased propensity to accelerate in SD, halt the test drive and install the original TCM.

See attached document for TCM adaption.

[E36Ron]

Preliminary observations: Very promising!

Installed this afternoon following instructions in last post above. (Note for Newbies: access the original TCM by 1. Undoing one bolt on the front (RHS) of the CD changer, allowing it to be moved out of the way, then 2. undoing the two nuts at the top and the two bolts at the bottom of the support frame for the CD Changer, giving full access to the TCM. My TCM had a piece of foam glued to the back in addition to its two retaining bolts.)

Followed the break-in instructions exactly: shifted through all gear positions with ignition ON, engine OFF, all indicator lights as expected. Then started the engine, drove the car at extremely light throttle in D-mode to the supermarket, a couple of miles of local streets and traffic lights away, never exceeding about 40 mph. Lots of opportunities for up and down shifts, even all the way up to fifth, as that is what D was designed to do. (Even noticed a low-speed TC lockup at one point.)

No observable difference in the D program after full engine and trans warmup. Presumably all pressure adaptations have taken place.

On the way back, I slipped the trans over into SD mode, with feather-light throttle at approximately 40 MPH. Trans immediately dropped down one gear!

This is phenomenal, and just exactly what I have been looking for! Clearly the S-shift map holds the car in lower gears than D does, but does so even at very light throttle.

Can't wait to see what it does at heavier throttle, because my preferred method of highway overtaking above 80 MPH without the S-mode was to use the manual shift to drop TWO gears (for a "cannonball" pass). Very likely at mid-throttle above 80 the swing over to S will accomplish the first downshift immediately, leaving only one pull-back of the shifter to get the second one. We shall see!

Highway tests tomorrow evening, will report back later in the week!

-- E36Ron

[Auraraptor]

Very cool! Which map did you go with? What’s your current final drive? I’ll be trying the 3.15 on my 3.23 final drive car hopefully this weekend when back at home. So excited!!

[E36Ron]

SD-2.81 for the 2.81 final drive.

Good luck with your installation! Let us know how it goes!

-- E36Ron

[Auraraptor]

Confirm above with only two minor addins:
10mm for all bolts except 13mm for batteries.
Agree make sure to remove the sticky pad before unlatching the TCM.
Takes <20 min to swap going slowly.
A2282596-BC86-4758-86F0-BEE9D7D827F1.jpg
DF871565-92FC-4977-AF0A-D3C01BE2C212.jpg

I’m still gently breaking in but so far no errors, mostly smooth shifts in comfort mode. Light throttle in sport and it definitely holds gears more than before. Please note initial throttle response is much more lazy particularly in comfort (I guess my old TCM had learned my driving style a bit too well) BUT no lock up or odd behavior. I’m sure that will resolve as it learns my throttle style. So far every excited and I can’t wait for it to liven up as it gets used to my right foot.

[E36Ron]

Highway Driving Update from Wednesday Evening Tests:

Note: results are partial, as I was not yet able to test at speeds over 100 MPH.

1. Previous suspicions confirmed! At all road speeds up to at least 100 mph, shifting from D to S immediately drops one gear, irrespective of throttle position.

2. Thus at 80 in D, where two lower gears are available, getting a two-gear downshift requires only the 15-degree side movement plus one pull-back of the handle, which is significantly quicker than the stock D-only situation requiring a left movement plus two pulls back.

3. It is not yet clear to me whether the S-mode ever upshifts to 5 in normal use below redline, but it certainly doesn't do so anywhere below 100 mph. (If it did not, that would mimic S-mode in the 4HP24 M70 motor situation.) (Going to be hard to test this, as redline in 4th gear with the stock differential is 161 MPH, i.e. above the electronic speed limit of 155 MPH.. :-) )

4. D-Program Kick-Down Evaluation: I am happy to report that, at 80 mph in D, a shallow but sharp accelerator press drops one gear, but a slightly deeper sharp accelerator press (but short of reaching the kickdown button) delivers a double-gear kickdown. Not sure if this was there previously in stock D, but don't think so, so this is terrific!

5. S-Program Kick-Down: Not yet evaluated. Since already one gear down at 80 MPH, with the second downshift available by pulling back the gearshift, we know it's there -- I just haven't tried it by kick-down yet.


Remaining tests to conduct all relate to comparisons between S and D from a standing start at various broad part throttle settings (such as tip-in, one quarter or one third, halfway, etc).

All such testing I have done so far is at light throttle, and is preliminary. Here the S-mode holds the car in the lower gears WAY up beyond the shift points in D-mode. For example, it shifts out of first only at 3,000 RPM (20 mph), even at light throttle. My assumption is that at slightly deeper throttle levels it will go to redline in each of the gears, but this is still to be tested.

An interesting question here regarding WOT performance from a standing start, is whether the availability of first gear at WOT in S-mode will provide an advantage, versus WOT launching from 2nd in D-mode? Once launched, the remaining time to 60 or 80 should be the same, as this is then all about WOT power (assuming redline shifts). But does the availability of 1st gear in S give it a launch advantage?

I suspect there will be a need for lots of long open empty straight flat roads, and considerable burning of rubber, to test this.

Not a lot of those in New Jersey, but maybe others elsewhere will pitch in here. I might try hooking up a data logger for these kinds of tests.

Looking forward to hearing of results from others!

Continuing overall conclusion: Wonderful!

-- E36Ron

[Auraraptor]

Likely because my car is still in learning mode but with the 3.15 sport program on my 3.23 rear end, it will shift at 4500 on very light throttle. I only tested this very briefly though. Add the car clearly wasn’t fully settled yet (shifts in sport were slightly choppy vs butter smooth in comfort). I will see if this continues to hold true as it better learns.

[MParallel]

May want to add to swap the wires for + and - so pulling the lever backwards is for upshifts and pushing the lever forward is for downshifts.
Surprisingly there are still performance cars build today with the reversed pattern, which is counter intuitive.

The pulling for upshifts, pushing for downshifts is the pattern of all sequential gearboxes ever used in racing. It follows the direction of forces.

[E36Ron]

Counter intuitive depends upon the perspective with which your intuition was built. Pre-Steptronic, the auto shift pattern was to pull backwards to reach a lower gear.

What you say about sequential gearboxes in racing probably explains why BMW reversed their pattern from 2002 onwards. I like it just the way it is.

[m6bigdog]

Counter intuitive depends upon the perspective with which your intuition was built. Pre-Steptronic, the auto shift pattern was to pull backwards to reach a lower gear.

What you say about sequential gearboxes in racing probably explains why BMW reversed their pattern from 2002 onwards. I like it just the way it is.

Counter intuitive, to say the least.
1) 850 is not a race car, good so far?
2) Yep! sequential manual gearboxes (hot ticket is dual clutch) are sweet, but this is not that.
3) If I drive a real H-pattern manual transmission car, there is no specific direction for the up/down shift. Just the way it is...
4) If you get in a car with an H-pattern manual transmission it would behooves you at some point to look at the shift pattern as some are different!
5) In my mind, if I Tip the shifter back (-) that is a down-shift and if I Tip the shifter forward (+) that is an up-shift; logical so far?
6) Now, if "YOU" reverse the up/down Tipping direction, it may match the sequential gear shift pattern "BUT" will not match the shift pattern on the console; not so logical!
7) So, what does this have to do with upgrading to an SD-TCM in the 850Ci-M73?

Things we contemplate...

[m6bigdog]

Highway Driving Update from Wednesday Evening Tests:
Note: results are partial, as I was not yet able to test at speeds over 100 MPH.
1. ..
2. ...
3. It is not yet clear to me whether the S-mode ever upshifts to 5 in normal use below redline, but it certainly doesn't do so anywhere below 100 mph. (If it did not, that would mimic S-mode in the 4HP24 M70 motor situation.) (Going to be hard to test this, as redline in 4th gear with the stock differential is 161 MPH, i.e. above the electronic speed limit of 155 MPH.. :-) )

4. D-Program Kick-Down Evaluation: I am happy to report that, at 80 mph in D, a shallow but sharp accelerator press drops one gear, but a slightly deeper sharp accelerator press (but short of reaching the kickdown button) delivers a double-gear kickdown. Not sure if this was there previously in stock D, but don't think so, so this is terrific!

5. S-Program Kick-Down: Not yet evaluated. Since already one gear down at 80 MPH, with the second downshift available by pulling back the gearshift, we know it's there -- I just haven't tried it by kick-down yet.
...
Looking forward to hearing of results from others!
Continuing overall conclusion: Wonderful!
-- E36Ron

Likely because my car is still in learning mode but with the 3.15 sport program on my 3.23 rear end, it will shift at 4500 on very light throttle. I only tested this very briefly though. Add the car clearly wasn’t fully settled yet (shifts in sport were slightly choppy vs butter smooth in comfort). I will see if this continues to hold true as it better learns.

Maybe we should put together a "Go-Fund-Me" for Ron... to help the get-out-of-jail and inbound fees should the +100 MPH runs get observed by the authorities..
In CA, anything over 100 MPH is a Misdemeanor that could include handcuffs and a vehicle tow.
Don't want to jinx it, be careful..

We should keep in mind the differences between the SD TCM 2.81 & 3.15 units in the comparisons and discussions.
E36Ron installed the 2.81
Auraraptor installed the 3.15

The 2.81 in SD-position holds 4th until the automatic up-shift @ redline RPM (approx. 6000)
The 3.15 in SD-position does not hold in 4th and will up-shift into 5th @ a lower than the automatic up-shift redline RPM.
The D-position AGS shift programs should be similar although I anticipate they are not exactly the same.
The D-Position, SD-Position and Manual mode all have automatic gear-change built-in, such as "up-shift" at redline and prevent "down-shift" that would result in over-revs.
In Manual mode a down-shift hold (M2-M1) will show by a flash of the shift request (M1) on the IC Display, then return to the current gear (M2).

I'm working at getting the more exact and definitive BMW official AGS and SD program descriptions, I'll pass them on if I can them, so stay tuned.
Until then, you can explore the 840 and 740 Steptronic program profiles in the BMW owner manuals or Technical Training Manuals, although they will not be exact..

All I know is the D-Position and SD-Position programs are well thought out..
Remember, BMW is an Autobahn car developer!!