1000rpm applying throttle not smooth
06-04-2019, 06:07 AM
#1
AudiWorld Junior Member
Thread Starter
1000rpm applying throttle not smooth
Does anybody else;s S4 not particularly like being around 1000rpm. I alternate between using D and S drive mode, but when in D as you know the gearbox tries to keep the revs lower. I've noticed that when the revs are around 1000rpm, sometimes when I go to apply throttle there's a little "jerk/jolt" much like a gear change feels like. This only happens if i've been coasting (no throttle) and then go and start to apply throttle quickly. For instance in traffic and I coast a little and then put my foot on the throttle, I feel it. Never feel it when driving at speed and i've not felt it in S mode, but then the revs are higher in general.
My cars only a month only, i'm just nearing 1000 miles, so it's possible these little things will disappear as I put on more miles ( it already feels smoother than when I first started driving it ).
My cars only a month only, i'm just nearing 1000 miles, so it's possible these little things will disappear as I put on more miles ( it already feels smoother than when I first started driving it ).
06-04-2019, 03:08 PM
#3
AudiWorld Senior Member
Is this an A4 or S4?
If it's an S4, the B9 S4 has a torque converter ZF transmission so ignore everything that I am going to say.
If it's an A4 with the 7-speed DSG and the 252HP 2.0T, then here is the deal as I have reverse engineered:
1. This engine has essentially zero torque below 1500HP, but tries to mask that with clever electronics (and an aggggressive first gear) that work brilliantly most of the time.
2. The transmission has two clutches, each of which have a gear selected. Switching to the other clutch and the pre-selected gear waiting for you there is... very quick... and smooth.
3. What the transmission usually does is keep the next-lowest gear pre-selected if you are travelling at a steady speed, so if you are in 6th, 5th is waiting on the other clutch. Tap the gas pedal very gently, the transmission shifts to the other clutch, you gain some RPM... and boom, movement.
4. Where you get into trouble is if switching to the next-lowest gear on the other clutch is not an option or does not get you above the 1500RPM sweet spot. If you're at 1000RPM, chances are, the next-lowest gear will get you at 1250-1300RPM. That doesn't solve your problem... so it needs to downshift again, so for example, if you started in 6th, it would switch you to 5th on the other clutch, downshift the original clutch to 4th, and then switch you back to that clutch. And those situations are where you start to see jerkiness...
5. In some cases when coasting, the clutch may disengage completely, I suspect... (but not sure there)
I think it should be obvious from the above why you wouldn't see this in S mode - a) you're more likely to be over 1500RPM already, and b) even if you're below 1500RPM, you're not going to be two whole gears away from going over 1500 RPM.
But bottom line, this is one of the weaknesses of dual-clutch transmissions...
If it's an S4, the B9 S4 has a torque converter ZF transmission so ignore everything that I am going to say.
If it's an A4 with the 7-speed DSG and the 252HP 2.0T, then here is the deal as I have reverse engineered:
1. This engine has essentially zero torque below 1500HP, but tries to mask that with clever electronics (and an aggggressive first gear) that work brilliantly most of the time.
2. The transmission has two clutches, each of which have a gear selected. Switching to the other clutch and the pre-selected gear waiting for you there is... very quick... and smooth.
3. What the transmission usually does is keep the next-lowest gear pre-selected if you are travelling at a steady speed, so if you are in 6th, 5th is waiting on the other clutch. Tap the gas pedal very gently, the transmission shifts to the other clutch, you gain some RPM... and boom, movement.
4. Where you get into trouble is if switching to the next-lowest gear on the other clutch is not an option or does not get you above the 1500RPM sweet spot. If you're at 1000RPM, chances are, the next-lowest gear will get you at 1250-1300RPM. That doesn't solve your problem... so it needs to downshift again, so for example, if you started in 6th, it would switch you to 5th on the other clutch, downshift the original clutch to 4th, and then switch you back to that clutch. And those situations are where you start to see jerkiness...
5. In some cases when coasting, the clutch may disengage completely, I suspect... (but not sure there)
I think it should be obvious from the above why you wouldn't see this in S mode - a) you're more likely to be over 1500RPM already, and b) even if you're below 1500RPM, you're not going to be two whole gears away from going over 1500 RPM.
But bottom line, this is one of the weaknesses of dual-clutch transmissions...
06-04-2019, 05:41 PM
#4
Is this an A4 or S4?
If it's an S4, the B9 S4 has a torque converter ZF transmission so ignore everything that I am going to say.
If it's an A4 with the 7-speed DSG and the 252HP 2.0T, then here is the deal as I have reverse engineered:
1. This engine has essentially zero torque below 1500HP, but tries to mask that with clever electronics (and an aggggressive first gear) that work brilliantly most of the time.
2. The transmission has two clutches, each of which have a gear selected. Switching to the other clutch and the pre-selected gear waiting for you there is... very quick... and smooth.
3. What the transmission usually does is keep the next-lowest gear pre-selected if you are travelling at a steady speed, so if you are in 6th, 5th is waiting on the other clutch. Tap the gas pedal very gently, the transmission shifts to the other clutch, you gain some RPM... and boom, movement.
4. Where you get into trouble is if switching to the next-lowest gear on the other clutch is not an option or does not get you above the 1500RPM sweet spot. If you're at 1000RPM, chances are, the next-lowest gear will get you at 1250-1300RPM. That doesn't solve your problem... so it needs to downshift again, so for example, if you started in 6th, it would switch you to 5th on the other clutch, downshift the original clutch to 4th, and then switch you back to that clutch. And those situations are where you start to see jerkiness...
5. In some cases when coasting, the clutch may disengage completely, I suspect... (but not sure there)
I think it should be obvious from the above why you wouldn't see this in S mode - a) you're more likely to be over 1500RPM already, and b) even if you're below 1500RPM, you're not going to be two whole gears away from going over 1500 RPM.
But bottom line, this is one of the weaknesses of dual-clutch transmissions...
If it's an S4, the B9 S4 has a torque converter ZF transmission so ignore everything that I am going to say.
If it's an A4 with the 7-speed DSG and the 252HP 2.0T, then here is the deal as I have reverse engineered:
1. This engine has essentially zero torque below 1500HP, but tries to mask that with clever electronics (and an aggggressive first gear) that work brilliantly most of the time.
2. The transmission has two clutches, each of which have a gear selected. Switching to the other clutch and the pre-selected gear waiting for you there is... very quick... and smooth.
3. What the transmission usually does is keep the next-lowest gear pre-selected if you are travelling at a steady speed, so if you are in 6th, 5th is waiting on the other clutch. Tap the gas pedal very gently, the transmission shifts to the other clutch, you gain some RPM... and boom, movement.
4. Where you get into trouble is if switching to the next-lowest gear on the other clutch is not an option or does not get you above the 1500RPM sweet spot. If you're at 1000RPM, chances are, the next-lowest gear will get you at 1250-1300RPM. That doesn't solve your problem... so it needs to downshift again, so for example, if you started in 6th, it would switch you to 5th on the other clutch, downshift the original clutch to 4th, and then switch you back to that clutch. And those situations are where you start to see jerkiness...
5. In some cases when coasting, the clutch may disengage completely, I suspect... (but not sure there)
I think it should be obvious from the above why you wouldn't see this in S mode - a) you're more likely to be over 1500RPM already, and b) even if you're below 1500RPM, you're not going to be two whole gears away from going over 1500 RPM.
But bottom line, this is one of the weaknesses of dual-clutch transmissions...
I've only noticed a significant delay in one particular situation, but it appears to be a consistent way to cause a lag in throttle/transmission response. If I'm approaching a sharp turn and let off the throttle completely in order to slow down, and then re-engage the throttle as I'm rounding the corner, it almost feels as if the engine has died for a split second when I roll back onto the throttle. Just nothing there when I depress the pedal until it all reconnects and gets going again. Very strange feeling. In this situation I assume the car is in (at least) second gear and is thinking we're coming to a stop, and therefore as 1st gear pre-selected on the 2nd clutch. When you roll back into the throttle the transmission's going "Oh ****, hold on a sec. I wasn't ready for that!". It would definitely be an issue in a track situation, but I suppose it could be negated by using the paddle shifters.
06-04-2019, 06:03 PM
#5
AudiWorld Senior Member
I've only noticed a significant delay in one particular situation, but it appears to be a consistent way to cause a lag in throttle/transmission response. If I'm approaching a sharp turn and let off the throttle completely in order to slow down, and then re-engage the throttle as I'm rounding the corner, it almost feels as if the engine has died for a split second when I roll back onto the throttle. Just nothing there when I depress the pedal until it all reconnects and gets going again. Very strange feeling. In this situation I assume the car is in (at least) second gear and is thinking we're coming to a stop, and therefore as 1st gear pre-selected on the 2nd clutch. When you roll back into the throttle the transmission's going "Oh ****, hold on a sec. I wasn't ready for that!". It would definitely be an issue in a track situation, but I suppose it could be negated by using the paddle shifters.
In terms of delay, in my experience, the 'best' way to generate delay is to get into a low-speed curve onto a highway onramp, then you head into the straight part of the onramp at like... 40km/h and some absurdly high gear that has you at like 900-1000rpm and when you push the gas you just have... nothing and nothing on the other clutch.
(For anyone in the GTA reading this, try the eastbound gardiner onramp at Evans/Horner, that is probably the only place that I've had a memorable instance in this car of just... pushing the gas pedal and nothing happens and nothing happens and the transmission jerks and finally you're way above 1500RPM and... wait a second, just how fast am I going now?)
I do think, having had my share of weird transmission behaviour at low speed in stop-and-go and other dense city environments, that the transmission kinda 'predicts' when you're slowing down to a full stop... and if it turns out to be wrong and you suddenly jab the gas, oops, other clutch isn't ready for that.
Sometimes I would really like to try this engine in this car with the ZF 8 speed auto of the S4...
06-04-2019, 06:23 PM
#6
AudiWorld Member
A4's DCT has some programming quirks yes, but I've grown to appreciate them over the years. For the majority of my driving I paddle shift. I know which gear I need to be when I come out of the corner (usually 2nd), engine brake, etc.
So from my point of view, there are enough ZF8 cars. If you want it, get one of those. I wish there were more DCT cars, or Porsche started making a compact Panamera or something along those lines. I know that I want DCT in all my cars until it no longer needs a transmission with an electric version.
Last edited by DeXel; 06-06-2019 at 06:20 PM.
06-05-2019, 07:28 AM
#7
What are the speeds and RPMs like? Are you really at low enough speed to be in second?
In terms of delay, in my experience, the 'best' way to generate delay is to get into a low-speed curve onto a highway onramp, then you head into the straight part of the onramp at like... 40km/h and some absurdly high gear that has you at like 900-1000rpm and when you push the gas you just have... nothing and nothing on the other clutch.
(For anyone in the GTA reading this, try the eastbound gardiner onramp at Evans/Horner, that is probably the only place that I've had a memorable instance in this car of just... pushing the gas pedal and nothing happens and nothing happens and the transmission jerks and finally you're way above 1500RPM and... wait a second, just how fast am I going now?)
I do think, having had my share of weird transmission behaviour at low speed in stop-and-go and other dense city environments, that the transmission kinda 'predicts' when you're slowing down to a full stop... and if it turns out to be wrong and you suddenly jab the gas, oops, other clutch isn't ready for that.
In terms of delay, in my experience, the 'best' way to generate delay is to get into a low-speed curve onto a highway onramp, then you head into the straight part of the onramp at like... 40km/h and some absurdly high gear that has you at like 900-1000rpm and when you push the gas you just have... nothing and nothing on the other clutch.
(For anyone in the GTA reading this, try the eastbound gardiner onramp at Evans/Horner, that is probably the only place that I've had a memorable instance in this car of just... pushing the gas pedal and nothing happens and nothing happens and the transmission jerks and finally you're way above 1500RPM and... wait a second, just how fast am I going now?)
I do think, having had my share of weird transmission behaviour at low speed in stop-and-go and other dense city environments, that the transmission kinda 'predicts' when you're slowing down to a full stop... and if it turns out to be wrong and you suddenly jab the gas, oops, other clutch isn't ready for that.
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06-05-2019, 07:33 AM
#8
No thanks. ZF8 is the reason is I did not get 2019 S4/S5. Despite of what people say I could still tell it's a slushbox, and does not have the same connection feel of DCT. It was also slower to shift gears to the point that I only needed few minutes on the test drive to rule it out.
A4's DCT has some programming quirks yes, but I've grown to appreciate them over the years. For the majority of my driving I paddle shift. I know which gear I need to be when I come out of the corner (usually 2nd), engine brake, etc.
So from my point of view, there are enough ZF8 cars. If you want it, get one of those. I wish there were more DCT cars, or Porsche started making a compact Panamera or something along those lines. I know that I want DCT in all my cars until it no longer needs a transmission with an electric version.
A4's DCT has some programming quirks yes, but I've grown to appreciate them over the years. For the majority of my driving I paddle shift. I know which gear I need to be when I come out of the corner (usually 2nd), engine brake, etc.
So from my point of view, there are enough ZF8 cars. If you want it, get one of those. I wish there were more DCT cars, or Porsche started making a compact Panamera or something along those lines. I know that I want DCT in all my cars until it no longer needs a transmission with an electric version.
06-06-2019, 02:44 AM
#9
Is the explanation same for my situation where i leave a traffic light to turn right or left and i also feel like the engine has shut off for a moment because pressing gas does nothing for a second or 2 before it comes alive? I usually have it on Eco mode.
06-06-2019, 06:21 PM
#10
AudiWorld Member
I recommend applying OBD mod that always shows the gear number, so you know what's happening.
Last edited by DeXel; 06-06-2019 at 06:28 PM.