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PDK confused

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Old 02-23-2014, 10:21 AM
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PDK confused

Weird thing today, I was out for the sunday morning leisure drive. I was at low speed in sport mode basically steady speed. I went WOT (not pressing kick down) and there was a delay or hesitation before the car downshifted and responded. It wasn't the engine but as if the PDK was expecting and ready for an upshift before WOT. It seemed like the engine was holding RPMs until it got the right gear ready and then engaged. Is this within the normal behavior of the PDK, it seems like I confused it with my driving style at that moment.
 
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Old 02-23-2014, 11:31 AM
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Maybe because you were in between flooring it and just half way down with the pedal??

Sounds normal if you were not flooring it completely. So maybe you were not exactly WOT after all?

Sounds pretty normal.
 
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Old 02-23-2014, 11:34 AM
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Originally Posted by akbjr
Maybe because you were in between flooring it and just half way down with the pedal??

Sounds normal if you were not flooring it completely. So maybe you were not exactly WOT after all?

Sounds pretty normal.
You maybe right, perhaps it wasn't full throttle, it happened fast but the delay felt long.
 
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Old 02-23-2014, 11:37 AM
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Originally Posted by Go123
Weird thing today, I was out for the sunday morning leisure drive. I was at low speed in sport mode basically steady speed. I went WOT (not pressing kick down) and there was a delay or hesitation before the car downshifted and responded. It wasn't the engine but as if the PDK was expecting and ready for an upshift before WOT. It seemed like the engine was holding RPMs until it got the right gear ready and then engaged. Is this within the normal behavior of the PDK, it seems like I confused it with my driving style at that moment.
Hesitation in throttle response or downshift or both? We're you in auto or manual?

I find that in manual the shift responses are kinda slow unless in in sport plus. So if I'm in manual I always use sport plus as it is closer to how I expect a manual trans to behave.. But in sport it seems to still do it when it wants to when in manual
 
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Old 02-23-2014, 11:41 AM
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Originally Posted by scatkins
Hesitation in throttle response or downshift or both? We're you in auto or manual?

I find that in manual the shift responses are kinda slow unless in in sport plus. So if I'm in manual I always use sport plus as it is closer to how I expect a manual trans to behave.. But in sport it seems to still do it when it wants to when in manual
Hesitation in downshift, throttle was holding rpms, and in auto mode with sport on.
 
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Old 02-23-2014, 12:06 PM
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I guess with 2 clutches, if it is ready to up or down shift based on what it predicts and you want it to do the opposite, you can expect a delay while it figures out what your intention is. I suppose a 1 second delay can feel long if you are expecting near instant reaction.
 
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Old 02-23-2014, 12:32 PM
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Originally Posted by Go123
Hesitation in downshift, throttle was holding rpms, and in auto mode with sport on.
Yeah that doesn't surprise me.. To me sport mode in auto isn't bad, but when jumping on the throttle depending on the conditions the shift response isn't necessarily instantaneous.

Also note, you can always force the downshift with the paddles when in auto mode. Generally I find when in auto and I force a downshift it happens almost instantaneously. (I realize that isn't the point of your post, but it is still handy)
 
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Old 02-24-2014, 10:17 PM
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Originally Posted by Go123
Weird thing today, I was out for the sunday morning leisure drive. I was at low speed in sport mode basically steady speed. I went WOT (not pressing kick down) and there was a delay or hesitation before the car downshifted and responded. It wasn't the engine but as if the PDK was expecting and ready for an upshift before WOT. It seemed like the engine was holding RPMs until it got the right gear ready and then engaged. Is this within the normal behavior of the PDK, it seems like I confused it with my driving style at that moment.
How do you WOT, but not press the accelerator far enough for kickdown?
 
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Old 02-25-2014, 07:28 AM
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Originally Posted by TTCarrera
How do you WOT, but not press the accelerator far enough for kickdown?
Pressed down to the kickdown button but stopping at the resistance point. My understanding is that is max throttle, pressing the kickdown is also max with a downshift.
 
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Old 02-25-2014, 09:27 AM
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What RPM was the engine holding RPM at?
Was it bogging, but slowly climbing?

When it finally downshifted was it just one gear or multiple gears?

Since you were driving non-agressively, I think the car adapted and gave you a non agressive response.
By persisting, with the throttle, you convinced it to take proper action.

I also found that Sport mode needs some assistance from the paddles, when you want instant downshifts, under non-agressive driving conditions.

Somehow, on a mountain road, where it knows what is going on, Sport Mode behaves exactly as it should.

Sport Plus, on the other hand, is always too agressive.

I dont think any automatic shift program can ever do exactly as you want in every condition.
It needs your input from the kickdown switch or paddles.
 

Last edited by lunarx; 02-25-2014 at 09:30 AM.
  #11  
Old 02-25-2014, 11:59 AM
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Originally Posted by lunarx
What RPM was the engine holding RPM at?
Was it bogging, but slowly climbing?

When it finally downshifted was it just one gear or multiple gears?
I recall it was holding around 4000 rpms, when it downshifted it was at least 2 gears and then accelerated fast. It was just strange for a moment to be in limbo, as if both clutches disengaged while it figured out I wanted to move fast.
 
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Old 02-25-2014, 12:02 PM
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Yeah, all good points. As I'm experimenting I'm noticing a lot of subtlety depending on current mode, engine loading and throttle.. I have noticed as well that when I want something to happen in sport - auto, a downshift via paddle works well. I've also found that even in "normal" auto mode... The use of downshift makes that experience a little more acceptable to me when I am using it (while retaining slightly better gas mileage when I'm not feeling in a particularly aggressive mood).

Another subtlety I've noticed was descending hills.. I've got a fairly steep grade street near my house with a speed limit about 40 mph.. Normally I'm used to an automatic the speed climbing very quickly in these situations and you tend to need brakes to keep the speed from rapidly increasing.

But it seems like the PDK just "knows" that I just want to hold the speed and keep holds me in a lower gear.. I suppose it knows from the negative engine load and no throttle.. But it is behavior I've not noticed in auto's before (but admittedly I've been driving Manuals for the last few years other than my wifes car..

However if there was one behavior I think I wish PDK had was to remember the previous trans mode when you switch from manual back into otto..

When I drive Manual, I almost always use sport+ for the more aggressive throttle response (also I'm noticing that the shifts seem to be more crips in sport+ even in manual.. Or at least I've convinced myself they are) ..

However I'll often flip back into auto mode for some reason.. And when I do, of course I'm in auto sport+ and then pretty soon the engine just starts screaming at red line.. Wish it just remembered what mode I was in the last time I was in auto mode or maybe more simply just flip back to normal when I go back into auto..



Originally Posted by lunarx
What RPM was the engine holding RPM at?
Was it bogging, but slowly climbing?

When it finally downshifted was it just one gear or multiple gears?

Since you were driving non-agressively, I think the car adapted and gave you a non agressive response.
By persisting, with the throttle, you convinced it to take proper action.

I also found that Sport mode needs some assistance from the paddles, when you want instant downshifts, under non-agressive driving conditions.

Somehow, on a mountain road, where it knows what is going on, Sport Mode behaves exactly as it should.

Sport Plus, on the other hand, is always too agressive.

I dont think any automatic shift program can ever do exactly as you want in every condition.
It needs your input from the kickdown switch or paddles.
 

Last edited by scatkins; 02-25-2014 at 12:11 PM.
  #13  
Old 02-26-2014, 05:12 AM
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Originally Posted by Go123
Pressed down to the kickdown button but stopping at the resistance point. My understanding is that is max throttle, pressing the kickdown is also max with a downshift.
Is that so ? I have been wondering about this. Not seen any technical evidence of this either way !
 
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Old 02-26-2014, 05:18 AM
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Originally Posted by lunarx
I also found that Sport mode needs some assistance from the paddles, when you want instant downshifts, under non-agressive driving conditions.

I dont think any automatic shift program can ever do exactly as you want in every condition.
It needs your input from the kickdown switch or paddles.
+1 ... in my case, when going slow in traffic and I get an opportunity to overtake I manually click down to a proper gear in anticipation of my overtake ... letting Auto mode do this is awfull, it wastes too much time until it has figured out I am overtaking resulting in a slowish and unsafe overtake ...
 

Last edited by bccars; 02-26-2014 at 05:20 AM.
  #15  
Old 02-26-2014, 06:04 AM
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Originally Posted by bccars
Is that so ? I have been wondering about this. Not seen any technical evidence of this either way !
This is directly from the manual implying full throttle is the point short of pressing the kick down button.

Kickdown
The kickdown function is active in selector-lever positions D and M.

For optimum acceleration, e.g. when overtaking, press the accelerator pedal beyond the full-throttle point (kickdown).
The transmission shifts down depending on the speed of travel and engine speed.
 


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