Jerky shifts at low speed?
10-19-2018, 11:53 PM
#1
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Jerky shifts at low speed?
Have you guys noticed that the transmission is pretty herky jerky around 12mph? Right around when you're rolling in traffic or whatever, you can feel the downshift and jerks the car a little. Super annoying especially in bumper to bumper traffic. I know a lot of people have said that the DCT is great. But it's great shooting through gears getting speed and power. In low speed movement, it's not as smooth as I thought and few have pointed out. Sometimes I also find that I am trying to accelerate and modulate power expecting go, but it doesn't happen til a certain speed so it's not turbo lag, the transmission seems to be confused sometimes. Other times, I can even feel a noticeable clunk/shudder when coming to a stop. Difficult to replicate, but it does happen.
10-20-2018, 12:17 PM
#2
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All the time and it’s one of the biggest annoyances that I have with this car. I find that it usually happens in D when the car downshifts for efficiency and then I give it light throttle to accelerate and the car responds with a jerky upshift. It’s most problematic for me in light LA traffic where things are flowing at anywhere from 10-30 mph and my driving pattern is to just coast and apply some gas every now and then. When I let off the gas the car is quick to downshift. This step is usually smooth but I’ll feel a jerk roughly 20% of the time. When I tap the gas to speed up I’ll get a jerk around 75% of the time. The infuriating thing is that this car is at least capable of smooth shifts but can’t do it all the time even under seemingly identical situations.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
10-20-2018, 12:52 PM
#3
All the time and it’s one of the biggest annoyances that I have with this car. I find that it usually happens in D when the car downshifts for efficiency and then I give it light throttle to accelerate and the car responds with a jerky upshift. It’s most problematic for me in light LA traffic where things are flowing at anywhere from 10-30 mph and my driving pattern is to just coast and apply some gas every now and then. When I let off the gas the car is quick to downshift. This step is usually smooth but I’ll feel a jerk roughly 20% of the time. When I tap the gas to speed up I’ll get a jerk around 75% of the time. The infuriating thing is that this car is at least capable of smooth shifts but can’t do it all the time even under seemingly identical situations.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
10-20-2018, 04:29 PM
#4
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All the time and it’s one of the biggest annoyances that I have with this car. I find that it usually happens in D when the car downshifts for efficiency and then I give it light throttle to accelerate and the car responds with a jerky upshift. It’s most problematic for me in light LA traffic where things are flowing at anywhere from 10-30 mph and my driving pattern is to just coast and apply some gas every now and then. When I let off the gas the car is quick to downshift. This step is usually smooth but I’ll feel a jerk roughly 20% of the time. When I tap the gas to speed up I’ll get a jerk around 75% of the time. The infuriating thing is that this car is at least capable of smooth shifts but can’t do it all the time even under seemingly identical situations.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
My car has around 11k miles now and the shifts have gotten noticeably better than when it was new so I’m hoping that they’ll continue to get better over time. I also drive a Porsche with PDK and while I understand that these cars are at different price points I find the PDK to be both significantly smoother and faster than the A4’s S-Tronic.
Must be nice with a Porsche as a primary, a bit jelly
10-20-2018, 05:13 PM
#5
AudiWorld Senior Member
I totally agree that this transmission is... less than great... in low-speed, stop-and-go city traffic. Makes me wish it was a torque converter automatic.
What you need to remember about the dual-clutch transmission is that it working well is dependant on the computer correctly pre-selecting the next desired gear on the other clutch. This... it doesn't necessarily do very well in stop-and-go traffic where you can suddenly go from accelerating (in which case you'd want a higher gear pre-selected) to slowing down (in which case you'd want a lower gear ready on the other clutch).
It doesn't help that this engine doesn't have much torque below 1500RPM and frankly, the powertrain is designed so that. in 'D', you are one-gear-higher than you should be in, so if you push on the gas even slightly, the transmission downshifts one gear to, hopefully, reach 1500+RPM and give you some power. If, for whatever reason, the computer has a higher gear preselected instead of lower, or shifting down one gear doesn't get you above that 1500RPMish threshold, then... oooops. Not pretty.
(This, BTW, is why people say 'S' mode is better - with 'S' mode you'll be in a gear that keeps you above that magic 1500RPM point)
Also, the transmission has a very aggressive first gear, which is one reason fuel economy is SOOOO BAD in low-speed stop-and-go traffic. It also means that it will upshift fairly quickly...
What you need to remember about the dual-clutch transmission is that it working well is dependant on the computer correctly pre-selecting the next desired gear on the other clutch. This... it doesn't necessarily do very well in stop-and-go traffic where you can suddenly go from accelerating (in which case you'd want a higher gear pre-selected) to slowing down (in which case you'd want a lower gear ready on the other clutch).
It doesn't help that this engine doesn't have much torque below 1500RPM and frankly, the powertrain is designed so that. in 'D', you are one-gear-higher than you should be in, so if you push on the gas even slightly, the transmission downshifts one gear to, hopefully, reach 1500+RPM and give you some power. If, for whatever reason, the computer has a higher gear preselected instead of lower, or shifting down one gear doesn't get you above that 1500RPMish threshold, then... oooops. Not pretty.
(This, BTW, is why people say 'S' mode is better - with 'S' mode you'll be in a gear that keeps you above that magic 1500RPM point)
Also, the transmission has a very aggressive first gear, which is one reason fuel economy is SOOOO BAD in low-speed stop-and-go traffic. It also means that it will upshift fairly quickly...
10-20-2018, 05:56 PM
#6
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I totally agree that this transmission is... less than great... in low-speed, stop-and-go city traffic. Makes me wish it was a torque converter automatic.
What you need to remember about the dual-clutch transmission is that it working well is dependant on the computer correctly pre-selecting the next desired gear on the other clutch. This... it doesn't necessarily do very well in stop-and-go traffic where you can suddenly go from accelerating (in which case you'd want a higher gear pre-selected) to slowing down (in which case you'd want a lower gear ready on the other clutch).
It doesn't help that this engine doesn't have much torque below 1500RPM and frankly, the powertrain is designed so that. in 'D', you are one-gear-higher than you should be in, so if you push on the gas even slightly, the transmission downshifts one gear to, hopefully, reach 1500+RPM and give you some power. If, for whatever reason, the computer has a higher gear preselected instead of lower, or shifting down one gear doesn't get you above that 1500RPMish threshold, then... oooops. Not pretty.
(This, BTW, is why people say 'S' mode is better - with 'S' mode you'll be in a gear that keeps you above that magic 1500RPM point)
Also, the transmission has a very aggressive first gear, which is one reason fuel economy is SOOOO BAD in low-speed stop-and-go traffic. It also means that it will upshift fairly quickly...
What you need to remember about the dual-clutch transmission is that it working well is dependant on the computer correctly pre-selecting the next desired gear on the other clutch. This... it doesn't necessarily do very well in stop-and-go traffic where you can suddenly go from accelerating (in which case you'd want a higher gear pre-selected) to slowing down (in which case you'd want a lower gear ready on the other clutch).
It doesn't help that this engine doesn't have much torque below 1500RPM and frankly, the powertrain is designed so that. in 'D', you are one-gear-higher than you should be in, so if you push on the gas even slightly, the transmission downshifts one gear to, hopefully, reach 1500+RPM and give you some power. If, for whatever reason, the computer has a higher gear preselected instead of lower, or shifting down one gear doesn't get you above that 1500RPMish threshold, then... oooops. Not pretty.
(This, BTW, is why people say 'S' mode is better - with 'S' mode you'll be in a gear that keeps you above that magic 1500RPM point)
Also, the transmission has a very aggressive first gear, which is one reason fuel economy is SOOOO BAD in low-speed stop-and-go traffic. It also means that it will upshift fairly quickly...
10-21-2018, 05:26 AM
#7
AudiWorld Senior Member
Holy crap that explains it. In city traffic, I get like 18mpg or less.. Highway cruise, 37mpg.. I'll keep an eye on 1500 rpm. I wonder if it can be fixed with programming or something they did in the refresh. I doubt it though, seeing how it was soo minor. BTW, when you switch modes between comfort, auto, etc. Do you actually notice any difference? The only thing I notice is more engine response in S, that's it.
I don't think this is something that can be 'fixed' - it's how this powertrain is designed. In fact, I would argue that this is one reason why they love the dual-clutch gearbox - one thing this transmission lets them do, I believe, compared to say a ZF 8-speed torque converter transmission, is to have both a very aggressive first gear and a very very very tall 7th gear (look at a magazine comparo where they listed 'RPM at 60MPH' - the A4 with this transmission is 400RPM lower than all the competitors with ZF torque converter 8 speeds)
In a more suburban/rural environment with less traffic where you can travel at a steady speed for a while, I might add, this works wonderfully. You come to a stop. Light turns green. Aggressive first gear gets you quickly into the >1500RPM band, then transmission upshifts as your speed goes up, keeping you in that power band. Once you reach the desired steady speed, transmission upshifts such that you're at about 1200RPM, which gives you very, very good fuel economy, and keeps one gear lower pre-selected on the other clutch. Tap the gas even a tiny bit to accelerate, transmission downshifts, your RPM goes up by 300-400RPM (which is unnoticeable unless you watch the tach), car accelerates very nicely.
Where this design is murderous is if you're in stop and go traffic where you go up to 1800RPM, then hit the brakes, then start again, etc.
I haven't played with the drive modes; I've always run mine in the default 'auto' mode...
Last edited by VM; 10-21-2018 at 11:03 AM.
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10-21-2018, 04:36 PM
#8
AudiWorld Member
I don't think this is something that can be 'fixed' - it's how this powertrain is designed. In fact, I would argue that this is one reason why they love the dual-clutch gearbox - one thing this transmission lets them do, I believe, compared to say a ZF 8-speed torque converter transmission, is to have both a very aggressive first gear and a very very very tall 7th gear (look at a magazine comparo where they listed 'RPM at 60MPH' - the A4 with this transmission is 400RPM lower than all the competitors with ZF torque converter 8 speeds)
10-21-2018, 04:44 PM
#9
AudiWorld Senior Member
For example, if you compare the ZF 6 speed vs 8 speed, first on the 6 speed is 4.171:1 and 6th is 0.691:1. The 8 speed has 4.714:1 first and 0.667:1 eighth, according to wikipedia.
Similarly, if you compare the GM 6L80 with the 8L90, first is 4.027:1, 6th is 0.667:1 on the 6L80, while on the 8L90, it's 4.56:1 and 0.65:1. (And a final drive between 2.85-3.27)
Meanwhile, if I googled the right specs, the DSG has a 3.19:1 first gear, a 0.39:1 seventh gear, (and a very aggressive 4.23:1 axle ratio which makes the numbers not comparable).
I'm not sure how to do the math to calculate the overall gearing range between all three.
Also, I wonder whether the 8-speed GMs or ZFs would start in first gear from a stop in light throttle. The Audi transmission definitely does.
Last edited by VM; 10-21-2018 at 04:50 PM.
10-21-2018, 05:28 PM
#10
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After tuning my car through APR, I have very little lag. It was very prevalent in the beginning. And as i put more miles on the car, the lag started to decrease. Then after the tune at about 15k miles the lag in the transmission was practically non-existent in my a4.