Low idle speed-off the line stumble.
#21
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Originally Posted by ULtraPLanet' date='Sep 16 2004, 09:51 AM
. . . AC on/off, fan on/off nothing seems to have any bearing on the idle speed. . . .
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.
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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.
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.
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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.
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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.
#27
Originally Posted by ULtraPLanet' date='Sep 16 2004, 09:51 AM
Alright today I was paying attention to exactly what is happening.? The hesitation seems to be in the Steptronic tranny.? Warm idle is 500 rpm's and when I touch the gas the rpm's jump immediately and the jerk seems to come from the transmission engaging.? AC on/off, fan on/off nothing seems to have any bearing on the idle speed.? Maybe the Steptronic needs to see a certain rpm before it engages for some reason although the car still lurches forward when you let off the break (auto creep).
[snapback]34804[/snapback]
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
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Originally Posted by noonehome' date='Sep 22 2004, 10:12 AM
[quote name='ULtraPLanet' date='Sep 16 2004, 09:51 AM']Alright today I was paying attention to exactly what is happening.? The hesitation seems to be in the Steptronic tranny.? Warm idle is 500 rpm's and when I touch the gas the rpm's jump immediately and the jerk seems to come from the transmission engaging.? AC on/off, fan on/off nothing seems to have any bearing on the idle speed.? Maybe the Steptronic needs to see a certain rpm before it engages for some reason although the car still lurches forward when you let off the break (auto creep).
[snapback]34804[/snapback]
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
[snapback]36981[/snapback]
[/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.
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