Long but worth the read for Tiptronic Owners

Part 1


As many of you know, EVOMS purchased and took delivery of a 997TT 6-speed in early July 2006. We were one of the first tuners to really dissect this new platform and make considerable changes to the cars performance. Since this time we have spent a ton of time learning, disassembling, testing, racing and driving this car to its limits. We have over 6K miles on it and it has seen everything from 115 degree top speed driving to 6000+ foot elevation testing, road racing, drag racing, home depot runs etc. We know this car and the way it performs like no one else.<O</O
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When we released our EVT tuning systems in December 2006, we felt that our development process and testing procedures were thoroughly tested and bulletproof for public release. Additionally, about this same time we set the record for the first 997TT to run into the 10 second range at the drag strip and currently we still hold this record. This was a major accomplishment as it took nearly 2 years for a 996TT to accomplish the same feat. <O</O
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OK, so why all this information that has nothing to do with a Tiptronic 997TT? Well at the same time we released tuning options for the 6-speed cars, we also released them for the tiptronic cars since the software coding within the ECU was the same. After installing a few of our EVT610 tuning systems on tiptronic cars in the past month, I had a chance to get some seat time in the car and see what the tiptronics performed like. Initially I was not very impressed and we had some customers with various stages of our EVT tuning systems with GIAC software remark that the car feels great some of the time and feels lame other times and the performance is inconsistent. Interesting?

I am one that likes to understand these cars 100% and I am not satisfied with the unknown. In the past 2 weeks I have spent an absurd amount of time trying to understand this tiptronic car and the power delivery with the tip transmission. Garrett at GIAC and I spend a ton of time trying to pinpoint the exact cause of the inconsistent power delivery and were willing to accept the fact that maybe there was something in the software that was missed during the 6-speed to tiptronic conversion. We spent countless hours deciphering data from my EVT 610 997TT 6-Speed, a stock 997TT 6-Speed, a 997TT Tiptronic with our EVT610 upgrade and a stock 997TT Tiptronic. We used the factory PIWIS scan tool as well as a custom data logging tool that GIAC made specifically for this testing. We acquired as much data as possible to see what the differences among the 4 different cars were.
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While I await part two, one quick question: Is any of this applicable to the 996TT Tip?

Thanks,

Craig

Ps: You have a PM Todd.

 

Part 2


After some time, we noticed a pattern on the tip cars that was not present in the 6-speed cars. The log below was taken from the tiptronic car. Notice the boost request and the actual boost. From 2307 RPMS to 3551 RPMS the ECU is asking for roughly 2350 mBar of boost and the engine is only producing ~ 1500 mBar of boost at 3051 RPMS and only ~ 2088 at 3551 RPMS which is still 194 mBar less that what the ECU is asking for. Additionally, the boost gauge in the car is showing the full 17 PSI at ~3000 RPMS which is not accurate as the engine is only seeing 7.35 PSI at this RPM.

997TT Tip Data Log

(see log in part 4)
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Now look at the log taken from the 6-speed car. Notice the boost request and the actual boost. From 2457 RPMS to 3000 RPMS the ECU is asking for roughly 2350 mBar of boost and the engine is producing ~ 1500 mBar by 2596 RPMS and produces a full 17 PSI of boost by 2768 RPMS. When comparing the 2 cars, the 6-speed car is making 15 PSI of boost about 820 RPMS sooner than the tiptronic car.

997TT 6-Speed Data Log

(See log in part 5)

When I was testing the tiptronic cars, I was in manual mode and was performing a ~2000 RPM roll in 3<SUP>rd</SUP> or 4<SUP>th</SUP> gear. With the 6-speed testing, the same RPM range was tested at WOT in the 3<SUP>rd</SUP> and 4<SUP>th</SUP> gears. When in the tip car, I would get to the desired gear and RPM and stomp the throttle. Because I was in manual mode, the car would not downshift and would hold the gear and do a full RPM sweep from 2000 RPMS to whenever I pulled my foot off the throttle. This was the exact scenario that I could feel that the car felt sluggish, ODD?? This is where I concentrated my testing and spent many hours collecting data here. I noticed that the stock tip car and the EVT610 tip car had similar data logs and miss matched boost requests vs. actual boost and much more lag when compared to the respective 6-speed cars at similar RPMS

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Good question. I would say yes, but I can confirm that in a few weeks

 

Part 3

OK, so why was this happening? Well after some more testing, sleepless nights and pondering the possible causes, I remember feeling a throttle step down switch on the tip cars @ WOT (Foot mashed to the floor). Typically automatic cars have these switches which when depressed, the engine would back down load to allow the auto transmission to downshift to prevent transmission and engine damage and allowing for a smoother shift. I then wondered if this could be causing the conflict between the TCU and the ECU when in manual mode and stomping on the throttle. I did some more testing and discovered that this was causing the boost delay and late spool up as compared to the 6-speed cars.

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I did some testing back and forth using the same car and data logging procedures. The only change that I made was the way I pressed the accelerator pedal. If I pressed the pedal to the throttle switch but not far enough to activate it, the car felt amazing. If I mashed the throttle and activated the switch, the engine/transmission felt conflicted until about 3800 RPMS where it had a slight hesitation and then continued its power sweep normally beyond 4000 RPMS.

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I confirmed this procedure many times on the road and could get it to repeat itself EVERY time. The data logs confirmed my hypothesis as well which lead me to the dyno testing. I wanted to test this procedure on the dyno to see how much power is being lost in manual mode with this switch activated vs. deactivated. I was amazed as to the outcome and now know why some customers were having sporadic inconsistent results with their tiptronic cars.

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The HP dyno below shows the same EVT610 Tiptronic car tested with and without the throttle step down switch activated compared to a stock 997TT tip with the throttle switch activated. At ~ 3247 RPMS both the stock (blue line) and the EVT610 (green line) are making ~ 170 AWHP at this point with the throttle switch activated. The (red line) is the same EVT610 Tip car in 3<SUP>rd</SUP> gear at WOT without the throttle switch activated. Power at 3247 RPMS is at 300 HP which is 130 more than the other 2 runs with the switch activated.

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This TQ dyno below shows the same EVT610 Tiptronic car tested with and without the throttle step down switch activated compared to a stock 997TT tip with the throttle switch activated. At ~ 3247 RPMS both the stock (blue line) and the EVT610 (green line) are making ~ 278 AWTQ at this point with the throttle switch activated. The (red line) is the same EVT610 Tip car in 3<SUP>rd</SUP> gear at WOT without the throttle switch activated. Torque at 3247 RPMS is at 483 TQ which is 205 more than the other 2 runs with the switch activated.

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In conclusion, I am baffled as to how this could be occurring on this car and I am tempted to make a simple throttle step down defeat on/off switch to eliminate this problem from occurring. I would like to get input from tiptronic owners as if you have experienced this scenario and have felt this same thing under this type of driving. I do not own a tip car and do not know if most people drive this way. I was informed of a potential problem and was asked to get it solved. After figuring it out, I hope this information is useful and if we can make a simple fix for it, let me know and I will get it done. Sorry for the long post, but I felt it was necessary

 

Thanks for the GREAT info Todd, and for the countless hours that you spent investigating this issue. As we have discussed, my car appears to lag more than 6Speeds with similar turbos. I am certainly prone to mashing my pedal all the way to the floor, thereby possibly invoking the throttle step down switch. I'm sure future testing will confirm or rebut this.

Is there any downside to defeating the throttle step down switch? If not, count me in!!

Craig

 

Thank you Todd! As I took my car yesterday I will test it today and I will let you know.. My car is Stock. (First tip car so dont have so much experience with it).
But if lets say take the scenario to defeat this switch and we are in automatic mode how are we going to make the car to downshift.?
Maybe only by pressing the up/down button from the wheel. (quite simple)
Many modified tiptronic cars here in Greece (NOT BY YOUR COMPANY) have issues with manual mode. (Safe mode etc) I believe your ecu dont have that issues.
Thank you again for the research!

 

Aisxos, Glad to hear your car arrived. The throttle step down defeat on/off switch would be an additional switch that would allow the driver to switch throttle step down switch on or off. When in automatic mode, the new switch would be on, leaving the switch like stock. When the car was in manual mode, the switch would then be turned off and allowing WOT driving without having to worry about the throttle position enabling this switch. Let me know what you fine with your car. Todd

 

I can't understand the difference. Maybe because my car is stock. I totaly understood what you mean...
For this reason if you need serious input, you have to sell me an Ecu and a switch. So please make me an offer and send it to me with a pm. I just need though a new spare Ecu.

 

Very intersting information Todd. Did you modify the Tiptronic brain at all? Maybe that's the only solution that will make a difference. These cars are so complicated and everything is wired to work to everything else. My totally novice opinion is that both the Engine ECU and the Tiptronic brain need to be modified to work togther as a unit to overcome this mismatch.

 

I am afraid that noone in the world has managed to modify the Tiptronic's brain yet..

 

Very interesting work. I would suggest tying the throttle switch defeat to the "sport" button if at all possible for a cleaner install

 

Any update here with the Tiptronic issue.. I still have exhaust + headers and no ECU..

 

Quick question... Porsche put that throttle step there for a reason... is there no danger in damaging the tranny if it was just shut it off?

 

I have a modded 02 X50 car with the tip and I agree with the "set" switch being a part of the system.. my car is not as bad now after modding or it has enough power now that It doesn't bother me as much. When I first started driving my car I posted on here "how do you launch a tip ?" My car would take off faster at part throttle than it did at FULL. I played around with the pressure on the gas to get quick take offs but was still hit or miss. I am not sure if my Protomotive ECU upgrade, 24/18 turbos, Fabspeed, BMC filter has anything to do with not "feeling" the sluggish take offs or not but it is better now. If you do come up with a defeat switch for a 996 I'll get one. I thank you for your efforts in defeating this and wish you good luck. Thanks, John