ColdList

I am posting some content of messages I have sent to a friend as I am seeking advice on this and I am hoping others may chime in on this and let me know if they have this experience. If you do experience this with your car please let me know.

I'm having what I think is a real issue and I need some opinion/advice I noticed the other day that if I am at a dead stop and I just mash the gas (not launch control) the car just sits there for a second or so then launches hard. It almost feels like massive turbo lag like you'd get in an 1980s turbo z :-) very weird. I am always in sport+ but I tried in normal mode too. Did it several times tonight. I know it didn't always do this as a few days ago I took of from a light like a rocket. So fast it felt like a launch. Very troubling.

The car is in fact very much warmed up. I am at a dead stop, mash the pedal and the car sits there for a good half second and the engine roars up to about 2k RPMS or so then it goes. It is a delay as if the tires were spinning and then the car got traction and took off except that the tires are definitely not spinning. Again, it's if I absolutely mash it to the floor from a stop. I wonder if it could be the car breaking itself so because tires are wanting to spin? That makes no sense to me though since it will do LC just fine. I only did a launch the other day because I felt it do this and I wanted to see if it would actually launch properly having felt it. Same thing tonight. 2 launches total.

Sulaiman

turn TC off and try if the same thing happen .... but do it on a safe spot u dont wanna spin it or lose control

ajag

I did not experience that, but I have not done immediate full throttle from a stop yet. Does it happen w/ partial throttle applications too? Perhaps when you give it immediate full throttle without full LC protocol w/ braking, it does some sort of "partial" LC where it builds boost then goes?

neanicu

This is just my opinion,I do not have hard data,but it sounds to me it might be PDK software related. It has been fixed now with a PDK software update. You definitely want to read this :


https://rennlist.com/forums/991/7641...rom-start.html

ColdList

Thank you. Tried that as well with same result. That was one of my initial suspicions too. I never remember having this with my TT.

ColdList

Thank you for the suggestion. I did read that thread and a couple others last night. Tech says software is different on the Turbo and I also suspect with the build dates of those cars being 2013 and mine being brand new that I would have the latest update too. At the dealer this am and there are no fault codes in the DME or PDK.

Problem is that there are no techs very experienced in the 991 TT/TTS yet. Not enough seat time so they are having a hard time figuring out if it is normal. I can't believe that it is.

ColdList

Not on partial accelerations at all. Only full throttle from a stop. Would love for someone to try this on theirs and let me know if they experience it.

Three techs saying they think it is fine. Ugh...

neanicu

When you do full throttle do you put the accelerator all the way to the floor? I don't know about the TTS,but most cars have a kickdown button behind the accelerator.

PMAA

My guess since it doesn't happen at all at part throttle is that it's a safety lag in the software just in case it was a mistake. However you would think that would be off in sport plus...looking forward to the real reason

Nick Yoskin

It is call "torque management"
DBW means the that the ECU can control opening rates, decay rates and a host of other PIDs

ColdList

Ok can you give me the laymans explanation please? Are you saying this is normal? Tried today again. Car is stopped in Sport+. I stomp on it. It slowly role forward for about a half second then pulls like a freight train.

Using LC there is no issue. Blurs your eyes.

Thank you in advance.

ColdList

Btw..just had my buddy in CA go out today in his car and try to replicate and he has ZERO lag. Steps on it and it takes off. Mine did not do this when I first got it. Prob. Is that techs just say "we have no experience with the 991 TTS yet and there are no fault codes so we assume it is fine.". NOT good enough!

Bluehinder

Well, you're just going to have to live with it for a while. No stop light racing.

ColdList

Very helpful. I'm sure you would enjoy this on your car.

cartester

I went out this evening with my TTS Cab like yours and performed your experiment. Yes, in Sport Mode (or any mode) when you just mash the throttle from a stop there is a sense the engine bogs down slightly then after revs climb to 2000 rpm or so it takes off like a rocket.

But I believe this is a normal result. Think about what is happening. If this were a normal manual transmission and you dumped the clutch from a very low rpm it would either stall or bog down until the revs climbed. The PDK is doing this except it doesn't allow a stall. The low rpm turbo nature of the engine may enhance this effect, as does the all wheel drive.

I didn't try an automatic transmission style brake torque launch where you hold revs while holding the car with the brake until the slack in the fluid is taken up. I don't really want to stress the PDK too much until there are a few more break-in miles on it.

I suppose the launch control start function exists to provide for those fast launches where a high initial rpm is required to avoid the bog.