Tim C

I am able to force RPM up to 750 from 500 by pressing Max AC. Because the compressor probably cycles on and off normally, I suppose it?s possible that this simply turned the compressor on when it had been cycled off. I haven?t experimented enough to say for sure. The last time I tried this, the RPM stayed at 750 well after returning it to the Auto position, which is peculiar considering it had been at 500 RPM. At 750 RPM, I don?t believe the hesitation occurs. I am going to experiment more to try to nail this down.

Whatever the variables, the hesitation, although intermittent, is very noticeable, and unacceptable to me. Some time soon I will be taking it to the dealer.

cjindustry

what is ds mode and how do you put it in, after i hear the answer, i will probably feel like an idiot :-p

northernmonkey

DS mode is "sport" mode for autos...

if lever is in D you just push it sideways towards the passenger side of the car...on the computer the D will now show DS...in this mode you can also use the steptronic function if you wish.

kscarrol

just to clarify what northernmonkey said, for those of us who drive on the wrong side of the road here in the US , you will be putting the car in D and pulling the shifter towards the drivers seat.

cjindustry

i have the sport mode, so if i move it over to this mode, do i have to use the shifter or will it still auto shift on its own?

kscarrol

If you simply move the stick over, it will function as an auto transmission in DS. If you push the stick forward, you will see M1 appear in place of DS, and you are now in Manual mode. Pulling the stick towards you moves up the gears (M1, M2, M3 and so on) while pushing it forwards moves down. Even in Manual mode, the computer will monitor your shifts and will not allow you to shift in a way that might cause damage, such as downshifting from M4 to M1. Driving in Manual mode takes a bit getting used to. Having driven mostly sticks in my prior cars, its came naturally to me, but I find that, like a stick, if you ease up on the gas pedal while shifting, it is much smoother. Just find a quiet street and play with it.

noonehome

So it sounds like the torque converter is not well matched to the idle speed(Or the other way around). When the engine spins the engine side of the torque converter, pressure is built up to spin the transmission side of the torque converter.
More thorough explanation:
http://auto.howstuffworks.com/torque-converter1.htm

Anyway, with the varying Idle, the engine speed of 500 RPM falls below the level at which pressure is generated and when we accelerate it quickly builds pressure and lurches. However, at 750 RPM there is a little pressure generated. If the torque converter were set for 500 RPM the car would pull relatively strongly as soon as you let of the brake when it's idling at 750RPM because of the 333 Ft Lb of torque of the 545.

Back in the 70's I think there were "high stall"( not sure of the name) torque converters that didn't generate pressure until 1500-2000 RPM to get the most out of the peak engine torque in the higher RPM range. They were used mostly for racing, maybe on the street.

As far as I know the torque converter can not be adjusted, only replaced with one that has different characteristics

Tim C

So it sounds like the torque converter is not well matched to the idle speed(Or the other way around). When the engine spins the engine side of the torque converter, pressure is built up to spin the transmission side of the torque converter.
More thorough explanation:
http://auto.howstuffworks.com/torque-converter1.htm

Anyway, with the varying Idle, the engine speed of 500 RPM falls below the level at which pressure is generated and when we accelerate it quickly builds pressure and lurches. However, at 750 RPM there is a little pressure generated. If the torque converter were set for 500 RPM the car would pull relatively strongly as soon as you let of the brake when it's idling at 750RPM because of the 333 Ft Lb of torque of the 545.

Back in the 70's I think there were "high stall"( not sure of the name) torque converters that didn't generate pressure until 1500-2000 RPM to get the most out of the peak engine torque in the higher RPM range. They were used mostly for racing, maybe on the street.

As far as I know the torque converter can not be adjusted, only replaced with one that has different characteristics
[/quote]


I would think the solution would be to keep the idle RPMs at 750 where the engine and Steptronic transmission seem to get along very well. With all the electronic controls aboard, this would seem very doable.