So I set the paddy’s to only function with the Sports mode on the selector and for the most part I am happy with spirited driving in this mode. Given that dynamic mode is not so easy to engage in certain situations, what I’m I leaving behind in terms of performance as it relates to the engine only?..omitting the steering, brakes and suspension for the purpose of the conversation.

Now I know the throttle response is augmented with dynamic mode, but I’m I losing engine performance (total output) in normal mode?

For example, throttle opening scale max=100% and pedal has the same 100% scale to match the TB opening at 100% in dynamic. Assuming the pedal input is linear, is Regular mode able to achieve 100% throttle opening? If not linear does dynamic have a dull spot say from 80% pedal to 100% since you would have reached 100% TB opening sooner?

And in winter mode does the opposite happen?

 

ricardoa1, my understanding of the system, you are correct in how the throttlebody responds. In dynamic mode, it is easier to get the throttlebody more open, therefore, you are going to have less response in say the second half of the pressing of the gas pedal. I don't think you are going to see any power difference in the output of the motor. You are just going to get more power with less input of the gas pedal because the throttlebody has opened up earlier.

As you are also thinking, in winter mode, the gas pedal becomes less responsive to power output to help the driver achieve maximum power appropriate to the conditions. It will also at some point limit the power when too much wheel slippage is sensed. The other trick included with winter mode is that it starts the car out in second gear vice first. This helps limit the amount of torque that can be generated, therefore, helping to ensure you don't break the wheels loose.

 

im convinced that the car starts in second gear in normal Drive (not sports, not winter, not competition modes)

 

If you have a decent OBD tool or SDD you can see what gear the car pulls away in then you won't have to surmise

I can't speak for the 8 speed gearboxes but the 6 speed gearboxes in the X150 XK and XKR definitely pull away in first gear unless they are in snow mode or manual paddle mode because I have used SDD to check and I suspect the 6 speed gearbox in the XF and XJ do the same.

 

the reason i stand behind my opinion, because when I have the car in Dynamic mode, with the transmission in sport, and i use the paddles, when i come to a stop, the car goes down to 2nd gear. NEVER first

 

That is because that is what the gearbox does in manual mode and is the reason why people think the same as you. The car has enough torque to pull away in second gear so doesn't need to drop back to first in manual mode but if you actually monitor the gearbox using a tool you are likely to see that in auto mode it always drops in to first gear. As I said before, the 6 speeds definitely do but I can't confirm what the 8 speeds do.

Here is a video of my '10 XKR in drive monitored using SDD. The bottom indicator is vehicle speed and the one above it is current gear. You will see that when I come to a halt the gearbox drops in to first gear:


It is very easy to check and even my $25 OBD tool displays which gear the car is in. I believe that a few XJ owners have the same tool so perhaps someone could check:

 

weird, annoying....but verrrry interesting. thanks for sharing that

 

So with the 8 speed on my 2013 you can feel the gearbox loading up differently as you select winter mode or regular mode, when sitting still, also stop start is a lot clunkier in winter mode, lurching from being in second. I actually enjoy driving in winter mode as I can modulate the gas pedal along better without whiplashing the passengers. I have not tested MPG as I believe starting in second will have a negative effect on mileage.

To my original intentions, I do want to assure all power is available when the gas pedal is pressed all the way down. I feel a down kick switch at the bottom travel of the pedal. And I hope the car then negates any mode and delivers all available power. If the torque maps are different between modes and its not as simple as the throttle blade opening vs the pedal, do we have other limitations? I actually don't like it if that is the case. I want full power no matter what mode the car is in as I need to feel confident of my cars power when overtaking or passing. It easy to select S on the shifter but very cumbersome and distracting to push the dynamic button or deselecting winter mode. Hence my original question. I dont like dynamic mode for daily use, but am I in restricted power mode if not in it?

 

ricardoa1, as for winter mode being selected, then yes, your car is starting out in second. That is part of the purpose of what winter mode does. By starting out in second, it limits the amount of torque the wheels see, therefore, minimizing any slip that they will experience. In addition to that, in winter mode, the car will allow a finite amount of wheel slip (more than is allowed via the normal traction control). The idea behind this is that a certain amount of wheel slip is good for moving ice and snow out of the way to help the car get to a surface that does have traction. Now, like with dynamic mode increasing how fast the power builds up based on how fast you press the gas pedal, winter mode does the opposite. It will actually slow how fast the motor can build up initially and then ramps it up later. So, yes, this can give the illusion that the gas pedal is a bit more gentle on acceleration. But, you are still going to generate 100% engine output with the gas pedal fully depressed.

As for limitations put on the car in the various modes, there wouldn't be anything like a speed limitation or something like that. Like I mentioned, the amount of wheel slip allowed changes between any other mode and winter mode. The way the gas pedal allows engine power to be made changes, and I am sure that there is a few changes that happen with other traction control systems. If you want, I can post up the system descriptions for the various modes from the service manual so you can read what jaguar says the differences are.

 

Yes I appreciate the input. I was hoping it’s a basic manipulation of the pedal vs the throttle blade as you are confirming. I was just fearful the torque tables in the tune are also altered for effect. Tuning modern computers for example on my mustang there are various torque tables depending on different situations and those need to be manipulated to see torque gains throughout. Throttle body sensitivity is only one part of many in modern tuning. I’m happy to hear a fully depress pedal in any mode puts the vehicle in 100% power delivery. This is crucial when timing gaps and lane changes during overtaking, and shamefully road rage situations.

i was just mentioning my second gear experience as there seems to be debate, while I don’t have empirical evidence, I can definitely feel a shift in my car when sitting still, similar to when 4x4 engages in a pick up truck. Torque converter also senses it and RPMs shift. I’m not sure what the older 6 speeds do but the 8 speeds do change gears.

 

ricardoa1, I have played with my 6 speed and I can confirm that the tranny starts in second in the winter mode. I guess a test I would do is simply to find a country road and do various accelerations from 0 to say 70 mph. You want to count the number of shifts that you feel/see. Keep in mind that you are going to be starting in 1 gear (most likely first), so, the next shift will take you to second, then third, more than likely 4th, you will then feel a "shift", but that will be the torque converter locking up, then on with the rest of the gears. So, if you count the number of "shifts" (include the torque converter locking up), then that will tell you the number of gears you went through. I think you may find that having a second person in the car to watch the tach is going to be helpful. hate to see you drive off the side of a road or something silly like that.

The shift that you feel engaging the winter mode is simply the tranny shifting from 1 to 2 without relative motion. This may cause a slight bump in the driveline.