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Sportback Engine chocking on kick-down

Evolution_Roy Sep 27, 2020

  1. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    Hi all, I am Roy, new member here!
    I have a RS3 model 2018. I noticed that sometimes the engine choke for a second on kick down.
    I can re-create the issue every time when cruising about 115 kph. D mode and car is in 7th gear.
    If I kick down the accelerator to the floor, the gear box will shift down (not sure to what gear) but the engine will choke for almost a second.... no power, just 'brrrbbbrrbrbbrr' noise from the exhaust. On the RPM it is about 6000 RPM. After the initial chocking, the engine comes back to life and the car accelerates.
    It happened to me also in other speeds and gears, sometimes it feels like the car actually decelerate... before the engine gets back to life.
    Any idea what this can be?
     
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  3. arf @66

    arf @66 Registered User

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    Mine does it too.its really annoying.
     
  4. JWAM

    JWAM Registered User

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    It's normal. It's like a sort of 'anti lag'. Clutch opens, revs build to get the turbo spooling (watch the boost gauge) - you hear a mini launch control type noise - then clutches engage in an appropriate gear and the car goes. It also happens if you pull (manually via paddles) 2-3 down shifts and floor it when in auto/d on the gear box and are just cruising. You can avoid it by down shifting yourself before giving the gas. I quite like it. ETTO.
     
    wuta3 likes this.
  5. wuta3

    wuta3 Registered User

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    Yeah personally, I like the car doing the BBBBBRRRRPP before it just snaps and takes off. Sort of cool.
    I've also found that because the car uses accel pedal position, speed etc to "guess" what'll happen next, you can tickle the pedal before kickdown so the map predicts the downchange. I'm not sure if the DSG is my friend or enemy but we try and get along.
     
    terminator x likes this.
  6. arf @66

    arf @66 Registered User

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    I guessed it was supposed to do it,why i havnt the foggiest idea.to design a high performance car that chokes up for a couple of seconds when it down shifts is just plain stupid.down shift on the m3 and it put you back into the seat and it was off without any hessitation.not put your head through the windscreen before it decides what its doing then ohh wait here comes the power now in a minute or two.its certainly no anti lag,lol.just hoping it will get mapped out when i take it in for the map.
     
  7. steve111b

    steve111b Registered User

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    During the Summer I have managed to get rid of the anti-lag (which I call power cuts). In the Winter I still get one or two power cuts during a kickdown. I am in Canada which has lots of cold temperatures and cold gives more power. More power creates more anti-lag. The other thing that creates more power is a reduction in weight. When I purchased new lighter wheels and tires I noticed more power cuts. Also, my car has the carbon ceramics which are lighter than the steel rotors.

    One mystery which I solved was a reduction in power. That turned out to be a clogged air filter. RS cars suck a lot of air and the conditions I drive in shortened the life of the filter.

    The first thing you want to do is select Dynamic after a restart. Dynamic has a different throttle response and a more forgiving ESC. It is a good idea to rule out any power cuts caused by the ESC (which cuts power in Comfort). Turning off ESC seems to help, but I cannot confirm it works. However, the big contributor to power cuts is going from no throttle to flooring it. As wuta3 has pointed out you need to have some throttle before you go for the kickdown. I started using the torque display to measure this (minimum throttle), but a more accurate display is the fuel consumption bar graph. Every car is different and of course road conditions, engine revs, and speed are all going to shift the power cuts to none or many.

    Next you need to avoid flooring it. The more throttle you use the more power cuts you are going to have. If you are in S6 you have the option (when going for a kickdown) of selecting S5, S4, or S3. You can select S3 without flooring it, and yes it takes a bit of skill.
     
  8. wuta3

    wuta3 Registered User

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    The responses in this thread are nonsense;

    The DSG gearbox, under certain conditions needs up to 0.5s to select a gear when not moving sequentially. If you are in S7 and you floor it, the gearbox will request say, S4 to put you slap bang in the middle of the power. Going from S7 to S4 requires some time, so the ECU holds the engine's revs until the clutch can engage after gear selection. That's the BBRRR hesitation.

    Now, crusing at 60mph in S7 and flooring it isn't going to result in instant, optimal performance with a DSG gearbox. Other gearbox designs (like a BMW torque converstion box) are quicker to respond but have other tradeoffs. They may be better, they may be worse, but you have what you have.

    Rather than confusing a gearbox that is trying to do its best for you, how about pushing the ******* stick in to M and changing yourself. That way, you don't have to depend on a TCU/ECU trying to guess what the **** you're doing when it is clearly programmed for a set of actions and situations that suit driving most of the time, for most people.

    It is a bit like complaining that your traction control doesn't let you slide about. Switch it off then.
     
    Count Drunkula likes this.
  9. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    Yes, that is what I felt once on kick-down, I thought the engine fell off the car, as there was a sudden deceleration that almost made my head hit the steering wheel. I am looking into options of remapping the DSG box together with engine stage 1 map. One thing they can do is delete the kick down function which I guess means that the gears will not shift too low.
     
  10. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    Yes, I understand the mechanics, and I have the same feeling with my Passat DSG 280hp. But with the Passat the shifts seems to make more sense (its a six speed DSG). On the Audi it sometimes feel the box went too low on the gears change, like it goes from 7 to 4 and it uses the 4 for a fraction of a second before going up again. Would have been much better if it went say to 5 and use the torque that is available, instead of going to 4th at 6000 rpm.
     
  11. wuta3

    wuta3 Registered User

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    Yeah I agree the shift points are a bit weird, especially S2/S3 at 30mph ... like the map is for km/h at normal driving. The downshift mapping is designed to put you at peak power, even if it whacks you near the redline and changes again. Just how it is. A gearbox remap helps the shift points though and generally stops a lot of the issues like (some) of the delay on downshifts and some of the low-speed bogging.
     
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  13. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    I always have the car in dynamic, it is just the gear box I change to 'comfort' or D mode. I think driving in S mode all the time is unpleasant, sounds like the engine is working hard, although the revs are not that high.
     
  14. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    It still happens sometimes even with the TVS DSG map. It is supper annoying that you press the gas pedal and the car decelerates instead of the expected accelerate. It is even twice as annoying becuase it makes you feel stupid that your body is ready for acceleration and instead your are being pushed forward because of the power cut.
     
  15. JWAM

    JWAM Registered User

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    I would imagine its an ecu thing rather than part of the tcu map. Not sure if ecu mapping can remove this? Perhaps someone with mrc/revo/apr/infinit/unitronic map could comment for you?
     
  16. Evolution_Roy

    Evolution_Roy Member Gold Supporter

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    I think it is part of the 'kick-down' gear box function, so when the kick-down is eliminated from the DSG, it should not be happening anymore...
     
  17. Djpfrozenp

    Djpfrozenp #RS3

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    I actually quite like the anti-lag\rolling launch feature.
     
  18. Slowracer

    Slowracer Registered User

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    I wouldn't call it a feature, its more of bug, the car has a brain fart about which gear it needs to change to.

    If it provided more performance id say cool, but it doesn't its slows the car and particularly annoying when it happens overtaking.
     
  19. D0C

    D0C Registered User

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    Agree completely.
     

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