Transmission Control Module (TCM) soft coding experiment. I did not remove the thunk but :-) ...

drhaller · 04-14-2002, 01:39 PM

*** WARNING/DISCLAIMER *** - Coding your Transmission Control Module outside of documented values may have undesireable effects. Coding of your Transmission Control Module is done enitrely at your own risk.

I performed a little experiment this afternoon as I promised I would do in a previous post. My car is a 2001 A6 2.7T with the 5-speed Automatic transmission.

The original coding was "00002". I changed it to "00022". This value is not documented in the Bentley manual.

Unfortuneately the thunk still remains... I did not get the "slam", but I can't always reproduce the slam so I can't say for sure if it has been removed.

The reason I tried the values that I did was from a post on the VAG-COM e-group a while ago. Since the value was from a totally different car (Passat) with a totally different transmission I did not know what to expect. I took the risk anyhow and luckily for me the coding was not a secret "self-destruct" code ;-).

This is what I observed:

(D - mode)
- transmission still upshifts through the higher gears as normal.
- transmission still automatically downshifts through the gears as you slow to a stop.
- dynamic shift programming (as visualized in measuring block 12) was no different than observed with stock coding.
- car would downshift when accel. was floored.

(Tip - mode)
- transmission will stay in 1st gear all the way to redline (with only mild accel. pedal pressure). In normal coding the car will shift to second around 2K RPM unless you absolutely stuff the accel. pedal.
- transmission will shift from 1st to 2nd if you let off the accel. pedal even a tiny bit. As stated above, it will stay in 1st all the way to redline and then shift to 2nd.
- transmission automatically downshifts through the gears as you slow to a stop.
- manual upshift/downshift behaves normally.
- you still cannot downshift to 1st if your speed is above 10km/hr. A good safety feature in my mind.
- car would downshift when accel. was floored.

/dan

Vincent in Montreal · 04-14-2002, 02:53 PM

But this is not a thing I would attempt on my car, I'm to affraid that my dealer discover it and it would probably void my waranty!!! But it is very cool.

drhaller · 04-14-2002, 04:23 PM

*** WARNING/DISCLAIMER *** - Coding your Transmission Control Module outside of documented values may have undesireable effects. Coding of your Transmission Control Module is done enitrely at your own risk.

I tried some additional TCM coding values:

"00000" - the original coded value remained after the recoding attempt. The Bentley manual describes this as an invalid value. Cool, as expected.

"00001" - the original coded value remained after the recoding attempt. Hmmm, the Bentley says this is a correct value for "Rest of World" but the TCM would not accept the code.

"00012" - Hmmm, another undocumented value was accepted. Read on!

First, with "00012" code, I should report that the transmission seemed to behave just like it did with stock coding value. The transmission seemed to shift normally and the 1st to 2nd shift behaviour was just like stock. All easily to determine behaviours seem to be the same as "stock" coding.

But, I did notice the following differences while doing data logging with VAG-COM. The differences showed up in measuring block 12.

Here are the details of measuring block 12 of the TCM.

I conjecture that it is display fields 2 and 4 in block 12 of the TCM that determine "past experience" and "current driver demand". I also conjecture that these numbers are what is used to determine the shift profile.

Before my experimentation it was my understanding that the "drivers" characteristics were "remembered" in the TCM across engine starts (this seems to be false). The Tiptronic transmission is marketed as able to select a shift program based on past driving style and current demands from a huge array of choices.

Now to the good stuff! Observations were made in "D" mode.

My observations with "00002" (stock) or "00022" coded.

- Display fields 2 thru 4 start at zero on engine restart.

- Display field 2 increases as driving gets more agressive. Seems to be a long term average of how "sporty" you drive. This number will go down (over time) if you start driving more relaxed.

- Display field 3 was always 0.

- Display field 3 seems to be a more near term "current" indication of how "sporty" you are driving. This number is constantly fluctuating.

My observations with "00012" coded.

- Display field 2 started at 50 when I started the car. Is this the undocumented sport mode that 2002 cars get?

- Display fields 3 and 4 start at zero on engine restart (same as observed with stock coding).

- Display field 2 increases as driving gets more agressive. Never went below 50 during my experiment. Seems to be a long term average of how "sporty" you drive. This number will go down (over time) if you start driving more relaxed.

- Display field 3 was always 0 (same as observed with stock coding).

- Display field 3 seems to be a more near term indication of how "sporty" you are driving. This number is constantly fluctuating (same as observed with stock coding).

/dan

BiturboBoy_V2.0_S3-- · 04-14-2002, 05:24 PM

this seems too cool...

drhaller · 04-14-2002, 05:36 PM

Singletrack · 04-14-2002, 05:52 PM

Paul C · 04-14-2002, 06:29 PM

Either way, it probably shouldn't affect the behavior when the car is in Tip mode, since you are (more or less) in full control.

drhaller · 04-14-2002, 06:35 PM

TXurS6 · 04-14-2002, 06:39 PM

If you tip it down and simultanously floor the accelerator it will drop from 2nd to 1st. This is with the stock programming on the 2001 2.7T.

TTS_4_to_A6 · 04-14-2002, 07:17 PM

operate differently. The one will stay in first gear until redline any time I am in Tip mode, and will let me downshift at any speed into first. I had the car into the dealer and they are puzzled. The other A6 automatically shifts into second if you lift off the trottle and will not let me downshift until I am below 10 mph.

I wish I had the ability to control first in my S4 the way I do on my A6.

04-14-2002, 01:39 PM	#1
drhaller Member Account #: 137 Join Date: Mar 2000 Posts: 1,063	Transmission Control Module (TCM) soft coding experiment. I did not remove the thunk but :-) ... * WARNING/DISCLAIMER * - Coding your Transmission Control Module outside of documented values may have undesireable effects. Coding of your Transmission Control Module is done enitrely at your own risk. I performed a little experiment this afternoon as I promised I would do in a previous post. My car is a 2001 A6 2.7T with the 5-speed Automatic transmission. The original coding was "00002". I changed it to "00022". This value is not documented in the Bentley manual. Unfortuneately the thunk still remains... I did not get the "slam", but I can't always reproduce the slam so I can't say for sure if it has been removed. The reason I tried the values that I did was from a post on the VAG-COM e-group a while ago. Since the value was from a totally different car (Passat) with a totally different transmission I did not know what to expect. I took the risk anyhow and luckily for me the coding was not a secret "self-destruct" code ;-). This is what I observed: (D - mode) - transmission still upshifts through the higher gears as normal. - transmission still automatically downshifts through the gears as you slow to a stop. - dynamic shift programming (as visualized in measuring block 12) was no different than observed with stock coding. - car would downshift when accel. was floored. (Tip - mode) - transmission will stay in 1st gear all the way to redline (with only mild accel. pedal pressure). In normal coding the car will shift to second around 2K RPM unless you absolutely stuff the accel. pedal. - transmission will shift from 1st to 2nd if you let off the accel. pedal even a tiny bit. As stated above, it will stay in 1st all the way to redline and then shift to 2nd. - transmission automatically downshifts through the gears as you slow to a stop. - manual upshift/downshift behaves normally. - you still cannot downshift to 1st if your speed is above 10km/hr. A good safety feature in my mind. - car would downshift when accel. was floored. /dan

04-14-2002, 02:53 PM	#2
Vincent in Montreal AudiWorld Super User Account #: 23527 Join Date: Aug 2001 Location: Montreal Posts: 8,422	Cool!!! But this is not a thing I would attempt on my car, I'm to affraid that my dealer discover it and it would probably void my waranty!!! But it is very cool. __________________ 2003 VW Jetta 1.8T

04-14-2002, 04:23 PM	#3
drhaller Member Account #: 137 Join Date: Mar 2000 Posts: 1,063	Results of further experimentation...(secret sport mode!?) * WARNING/DISCLAIMER * - Coding your Transmission Control Module outside of documented values may have undesireable effects. Coding of your Transmission Control Module is done enitrely at your own risk. I tried some additional TCM coding values: "00000" - the original coded value remained after the recoding attempt. The Bentley manual describes this as an invalid value. Cool, as expected. "00001" - the original coded value remained after the recoding attempt. Hmmm, the Bentley says this is a correct value for "Rest of World" but the TCM would not accept the code. "00012" - Hmmm, another undocumented value was accepted. Read on! First, with "00012" code, I should report that the transmission seemed to behave just like it did with stock coding value. The transmission seemed to shift normally and the 1st to 2nd shift behaviour was just like stock. All easily to determine behaviours seem to be the same as "stock" coding. But, I did notice the following differences while doing data logging with VAG-COM. The differences showed up in measuring block 12. Here are the details of measuring block 12 of the TCM. I conjecture that it is display fields 2 and 4 in block 12 of the TCM that determine "past experience" and "current driver demand". I also conjecture that these numbers are what is used to determine the shift profile. Before my experimentation it was my understanding that the "drivers" characteristics were "remembered" in the TCM across engine starts (this seems to be false). The Tiptronic transmission is marketed as able to select a shift program based on past driving style and current demands from a huge array of choices. Now to the good stuff! Observations were made in "D" mode. My observations with "00002" (stock) or "00022" coded. - Display fields 2 thru 4 start at zero on engine restart. - Display field 2 increases as driving gets more agressive. Seems to be a long term average of how "sporty" you drive. This number will go down (over time) if you start driving more relaxed. - Display field 3 was always 0. - Display field 3 seems to be a more near term "current" indication of how "sporty" you are driving. This number is constantly fluctuating. My observations with "00012" coded. - Display field 2 started at 50 when I started the car. Is this the undocumented sport mode that 2002 cars get? - Display fields 3 and 4 start at zero on engine restart (same as observed with stock coding). - Display field 2 increases as driving gets more agressive. Never went below 50 during my experiment. Seems to be a long term average of how "sporty" you drive. This number will go down (over time) if you start driving more relaxed. - Display field 3 was always 0 (same as observed with stock coding). - Display field 3 seems to be a more near term indication of how "sporty" you are driving. This number is constantly fluctuating (same as observed with stock coding). /dan

04-14-2002, 05:24 PM	#4
BiturboBoy_V2.0_S3-- Elder Member Account #: 13456 Join Date: Dec 2000 Posts: 12,499	you can do this with JUST a a regular VAG tool (like the rosstech one?)? this seems too cool... __________________ AWESOME post, funny and informative for newbs...its not all right but i suggest you click!

04-14-2002, 05:36 PM	#5
drhaller Member Account #: 137 Join Date: Mar 2000 Posts: 1,063	Yes, in fact I used VAG-COM from Ross-Tech.

04-14-2002, 05:52 PM	#6
Singletrack AudiWorld Super User Account #: 25380 Join Date: Sep 2001 Posts: 16,037	Very interesting, you have balls for just changing the coding. __________________ 2008(9?) S5 - ordered 3/29/08 2004 Subaru Impreza WRX STi 2000 A6 2.7T - Sold "On the run from Johnny Law; ain't no trip to Cleveland."

04-14-2002, 06:29 PM	#7
Paul C Junior Member Account #: 1244 Join Date: Mar 2000 Posts: 964	You don't say, so I presume this was in "D" rather than "Tip" mode? Either way, it probably shouldn't affect the behavior when the car is in Tip mode, since you are (more or less) in full control. __________________ 2000 S4 Pearl White 2001 allroad Atlas Gray 1991 Alfa Romeo Spider <A HREF="http://www.dieGrenze.com" target="_blank"> </A>

04-14-2002, 06:35 PM	#8
drhaller Member Account #: 137 Join Date: Mar 2000 Posts: 1,063	"D" mode (thanks, I'll update the thread).

04-14-2002, 06:39 PM	#9
TXurS6 Member Account #: 9795 Join Date: Sep 2000 Posts: 7,277	It is possible to drop from 2nd to 1st above 10km/hr... If you tip it down and simultanously floor the accelerator it will drop from 2nd to 1st. This is with the stock programming on the 2001 2.7T. __________________ Jim formerly FtWorthS4 1997 S6

04-14-2002, 07:17 PM	#10
TTS_4_to_A6 Junior Member Account #: 15283 Join Date: Jan 2001 Posts: 2,310	Strange, I have 2 2000 A6s in my family and they both operate differently. The one will stay in first gear until redline any time I am in Tip mode, and will let me downshift at any speed into first. I had the car into the dealer and they are puzzled. The other A6 automatically shifts into second if you lift off the trottle and will not let me downshift until I am below 10 mph. I wish I had the ability to control first in my S4 the way I do on my A6.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode


Discussion Forums:	Advanced Search