Originally Posted by Router-Dude

I have a slew of questions that keeps getting longer as I research further on how engine control on 991.2 cars work.

Some of my questions are about the 991.2 and how it nominally functions in general, while others are specific to how a cobb protune implements (if at all) some of these functions.

Reference Material:

I have been reading the Cobb tunning Porsche 991.2 / 718 tuning guide.

I am specifically interested in the 991.2 Turbo / Turbo S application

Here is a link to the tuning guide in general (I will include specific excerpts below where needed:

https://cobbtuning.atlassian.net/wik...8+Tuning+Guide

Porsche Driving Mode questions (OEM state)

Looking at the Driving Mode table from the 991.2 Turbo Owner's Manual (See Image at bottom of post)):

"Response"
What does "Response" mean specifically (1st row of "Drive" section of table)?
Throttle response. In laymans terms: Normal mode is somewhat "lazy" and you don't get full boost. Think eco mode. Sport mode is self explanatory, a sportier throttle response and sportier PDK mapping you get full boost (turbo PSI) you get backfires from the exhaust on downshifts and when lifting of the throttle under load. Sport + mode I like to think of as the true intended mode for the car. Full boost, holds gears much longer/higher than other modes. PDK mapping at it's peak, throttle mapping at it's peak. The raciest mode.
Is this the maintenance of low levels of boost (1-2) psi) while off-throttle in Sport+ mode?
Not sure the question here but yes Sport + holds 1-2 psi of throttle. Sort of like keeping the turbocharges primed for faster response and to eliminate lag.
How is this low level of boost maintained? Diverter valve or VTG functionality, or other?
Computer.

“Backfire”
I notice this as popping and cracking on off throttle in the 4K+ rpm range. Is this accomplished by running rich? If so, is this running rich also causal to the temp reduction we see in Sport Mode? What else contributes to the temp reduction?
Popping and crackling is an artificial feature programmed into the ECU by porsche while in sport mode.
It doesn't run rich, it basically squirts excess fuel in a way to create said popping/crackling. Sport + reduces oil temps for racing purposes. Not sure how the car achieves this but it's also through programming. Coasting on the highway off throttle with the clutch disengaged lowers oil temps. Either by putting the car in neutral or if you're in normal mode the car will go into a "sail" mode by dropping the revs to idle while allowing you to roll freely without engine brake.

“PDK”
I see 4 PDK profiles, from the table: Normal, Sport, Performance, and Sport Response.
Is there more information about the differences between these 4 PDK profiles?
Sport response is just a quick button on tap that gives you Sport + for 20 seconds. It has it's use but I never used it. Think of it as a "push to pass" button. You're cruising along in normal mode, you want to pass someone or need a quick burst and you push the sports response button without toggling the wheel to Sport +. After 20 seconds it goes back to the mode it was in or you can press the button again to cancel it.

PDK mapping changes with every mode with each one getting progressively more aggressive.

“PASM/PDCC/Rear axle steering”
What is the difference between “Sport” and “Sports Chassis”? I have not found any further information on this one.
Shock rebound, that's it.

“PSM”
It looks like PSM in not coupled in any way to Driving Mode selector, but always a manual selection, is this correct?
Yes. PSM sport (quick press of traction button) allows wheel spin to an extent and keeps stability management active. PSM off (long hold of traction button) disables all nannies.

PSM has two stages of toggling. PSM sport or PSM off. Technically it's 3 stages because the default stage is PSM on.


Cobb Protune questions:

Do Cobb Protuners generally make use of the separate Normal and Sport tables to mirror oem mode differences (relatively)? Does anyone have a protune that keeps the “Wife” (Normal) mode, spouse safe?
Yes and no. Every mode gains power/response. Especially if you install PDK maps (highly recommended). Still, the car will have basically OEM/stock daily drivability. Nothing to worry about.

No Cobb protune, or any protuner will map/mirror your car like OEM Porsche. Especially when you go for bigger power. If anyone tries to tell you otherwise they're full of it. Try any tune/protune yourself for an extended period of time then flash back to stock. You'll see what I mean. Nothing will be as smooth and dialed in as the stock map, period. As amazing as protunes are, there's a magic to the OEM stock map that's very satisfying. Especially when you switch back to stock after some time.

That's not to say the protunes are not smooth, they absolutely are and I'd rather drive on a protune any day vs stock. But the amount of dialing in needed to achieve this would require a tuner countless hours of testing and tuning. It's not to say that they can't do it, but tuners are out there trying to achieve power gains primarily. I've tried maps from several tuners, each has their own style but none of them are OEM mirrored that covers every single metric in every mode at every speed/rpm/throttle input. With that said, don't let that dissuade you. Protune all the way.

Apparently there are only 2 engine "maps" Normal and Sport in the ECU, Implies that Sport and Sport+ differ in ways other than "map" (See above for “Response” and “Backfire”.

From Cobb Tuning Guide: " . . .These tables are separated into Normal and Sport mode. Normal and Sport mode are accessed by the driver through a selector on the steering wheel. COBB OTS maps have these modes set to the same values across all maps so the car makes the SAME power in Normal and Sport modes. However, it is entirely possible to set normal and sport modes to different power output. Some customers for example may want a low power tune for valet or use by an unskilled driver the wife. While others may want separate street and track modes. . . . "

Is there a linear relationship in torque request between Normal and Sport maps stock? (i.e., normal map is sports torque request (based on lookup intersection) minus 25% (or vice versa) for all normal values), or does the oem normal and sports have different shape torque request curves?

The Cobb tuning guide is self explanatory. To answer your question, yes the torque request is linear between the two. The differences between the two are mainly in the engine/throttle response and PDK response. Normal mode will make less top end power under wide open throttle than Sport. Otherwise under non wide open throttle it's basically the same but sport mode will react noticeably quicker and be slightly more aggressive. Compared to sport, normal mode can feel a bit sleepy.

Will a Cobb Protune in Sport mode still have the rich/backfire that gives more exhaust character while also running a bit cooler (due to richer?)?
Yes.

Is the Overboost condition in the Cobb tuning guide triggered by the “Sport Response” button on 991.2 Turbo/Turbo S cars?
I guess so. "Overboost" = Sport+. Some say that it makes more torque (stock map) but I think it's more of a marketing gimmick. I was never able to feel a difference between Sport + and the Sport Response button.
Cobb PDK maps:

Does cobb pdk tune have any interaction with driving modes? I see there are 4 pdk profiles normally, from the table: Normal, Sport, Performance, and Sport Response. Does Cobb use different tables, or would the PDK always be in whatever profile the Cobb applied?
Yes. Different tables.


Driving Modes (991.2 Turbo Owner's Manual)

Originally Posted by Router-Dude

Bump.

I know someone has at least one answer to some of my questions .. help a fellow forum member out, share a little.

Originally Posted by Router-Dude

@911dude41 : Thanks for taking the time to read and respond to my questions, it is greatly appreciated!

Follow-up on Cobb PDK, with Cobb Pdk applied, there is a difference in shifting behavior between the Porsche driving modes? That is great to hear, I had read some where that once you applied the Cobb pdk, that the Pdk was always in the same profile, regardless of selected Porsche driving mode. I hope I understood your answer correctly.

Thanks again.

Originally Posted by Router-Dude

@911dude41 I don’t care what anybody says, you are a scholar and a gentleman.

In all seriousness, thanks again for your feedback and clarifications.