Did anyone notice the low speed the jerkiness and knocking sound of the transmission
#1
Did anyone notice the low speed the jerkiness and knocking sound of the transmission
Got my TLX 2.4 Tech for almost a month(since Aug 13th), I am generally satisfied with this car, but there are some abnormal reaction of the transmission really annoyed me.
I can confirm the 8 speed DCT is a great transmission which shifting fast and smooth when you step on the gas pedal all the way down. But, I have notice some jerkiness and even knocking when driving in low speed, especially when the car hadn't been warmed up.
At the first or, second day after I brought the TLX, when I drove in normal mode and tried to stop in front of a red light, while I try to brake the engine is rev up and feels want to jump forward. Then I tried to apply the brake harder, the car did stop but with knocking sound coming from under the hood. Sounds like "Bong".
This is not happening every time when I tried to stop, but I had experience at least 20 times for the past month.
except this, I also notice when you move from Neutral to Drive, the transmission will have a sudden torque push the car forward after 1 second you made the switch then disappear within 0.5 secs.
I have a 2014 RDX AWD, it's tranny is silk smooth when switch from N to D
I can confirm the 8 speed DCT is a great transmission which shifting fast and smooth when you step on the gas pedal all the way down. But, I have notice some jerkiness and even knocking when driving in low speed, especially when the car hadn't been warmed up.
At the first or, second day after I brought the TLX, when I drove in normal mode and tried to stop in front of a red light, while I try to brake the engine is rev up and feels want to jump forward. Then I tried to apply the brake harder, the car did stop but with knocking sound coming from under the hood. Sounds like "Bong".
This is not happening every time when I tried to stop, but I had experience at least 20 times for the past month.
except this, I also notice when you move from Neutral to Drive, the transmission will have a sudden torque push the car forward after 1 second you made the switch then disappear within 0.5 secs.
I have a 2014 RDX AWD, it's tranny is silk smooth when switch from N to D
#3
Sorry, I am not very good at explain things like this.
#4
I also have experienced the jerkiness in slowly accelerating traffic and the "bong" noise on a couple of occassions when nearing a stop. I inquired at the dealership about this and test drove another 4 cyl 8DCT with similiar characteristics. The dealership asked that I keep monitoring and report back when the nuances occur but the manager believes this is normal because it has 8 gears to select from and the TC can magnify the symptoms when the transmission is trying to select the appropriate (or anticipated) gear.
#5
Instructor
Sorry I'm not really sure about the knocking sound, I have the V6 with the 9 speed AT and if it's in sport+ mode the transmission will downshift when I slow down, I'm guessing it's preparing for a turn or something to try and help me slow down then be in the correct gear to power out of the turn, and in Econ and Normal modes if I hit the brake pretty hard it will downshift to help slow down with engine braking.
#6
Instructor
I have noticed a little bit of "jerkiness" (if that's the best word for it) on my TLX since purchase. I have been driving in Eco mode on purpose -- I plan to for an entire week, followed by a week of normal and then a week of Sport to get a solid feel for each driving experience.
At this point I'm chalking it up to the Eco mode trying it's best to maximize mileage by staying in a higher gear as long as possible during deceleration, and moving to a higher gear as quickly as possible upon acceleration. This is just a guess tho....I'm no expert on transmissions to be sure. But I am keeping a watchful eye, ear and "feel" on it.
At this point I'm chalking it up to the Eco mode trying it's best to maximize mileage by staying in a higher gear as long as possible during deceleration, and moving to a higher gear as quickly as possible upon acceleration. This is just a guess tho....I'm no expert on transmissions to be sure. But I am keeping a watchful eye, ear and "feel" on it.
#7
Moderator
Ah the early adopters!!!
I'm not getting what I would consider to be jerkiness but when moving very slowly (from light to light in heavy traffic) it seems to want to shift just as I nudge the gas which causes it to kind of want to jump forward.
I'm not getting what I would consider to be jerkiness but when moving very slowly (from light to light in heavy traffic) it seems to want to shift just as I nudge the gas which causes it to kind of want to jump forward.
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#9
Moderator
#10
BTW, the new trannies also use a new tranny oil, not the usual DW1. So it may not be the torque converter or the software but the tranny oil. Not sure what the process of checking the tranny oil on the new DCTs is, but check the tranny oil level after sitting overnight before starting the engine.
Just a thought...
Just a thought...
#11
I doubt it - I've experienced the noticeable shifting at low speeds (stop and go traffic as i mentioned in my review) but considering the 8 gears, it seems normal. You quickly press the gas to go forward, it shifts a gear up, then you let off the gas or press brake to slow down and it shifts back down - I think its just a side effect of having so many gears, it's eager to shift - not really an issue. Most of us aren't used to having this many gears (I only had 5 in my TSX), so it'll take some adjustment to get used to it and possibly adjust our driving style a bit.
#12
AcurAdmirer
DCT's are notorious for being "jerky", even in high-dollar exotics. Acura tried to smooth out the clutch engagement by inserting a torque converter into the driveline between the engine and the clutch pack, but it sounds like it might not have been completely successful.
The OP's car might need to go back to the dealer, but for most of you with the DCT, it's the trade-off for those crisp shifts.
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The OP's car might need to go back to the dealer, but for most of you with the DCT, it's the trade-off for those crisp shifts.
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JeffS (09-09-2014)
#13
Maybe the answer is to leave the car in sport+ mode and do all the shifting yourself. Of course that will make it harder for you to send a text, eat a burrito or put on your lipstick while driving in slow traffic, but that's the price you pay for DCT performance.
#14
DCT's are notorious for being "jerky", even in high-dollar exotics. Acura tried to smooth out the clutch engagement by inserting a torque converter into the driveline between the engine and the clutch pack, but it sounds like it might not have been completely successful.
The OP's car might need to go back to the dealer, but for most of you with the DCT, it's the trade-off for those crisp shifts.
.
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The OP's car might need to go back to the dealer, but for most of you with the DCT, it's the trade-off for those crisp shifts.
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So I think it could be smooth out by some software upgrade, hopefully.
#15
Intermediate
I'm experiencing the jerky transmission shifts usually when the car is cold and is running at higher idle RPM. Also sometimes when I decelerate to near stop and then accelerate.
#17
I posted this in my thread where I tried to give some updates as I drove the car, but even the V6 at low speeds can be somewhat "jerky" like it's hunting around for gears or something. You may notice it in rush hour/bumper-to-bumper traffic. I don't really notice it at faster speeds, but then I've been taking it easy on the engine/transmission ... that should change a bit by this weekend or next week.
#18
Racer
Well, they damn well better fix it (V6 versions also - from another thread). This is a deal breaker for sure. Not at all what one would expect from a luxury car, even an entry level car that's value priced.
#19
Moderator
#20
I agree, this "jerky" feeling is definite annoying. The knocking sound is loud and make me feel it may causing damage to the transmission.
#21
a Big Thank to this thread!
I was planning to pull trigger today for the WHITE/ESPRESSO ADVANCE this week but this is a DEAL BREAKER for me now
I will wait until the problem is solved.
I was planning to pull trigger today for the WHITE/ESPRESSO ADVANCE this week but this is a DEAL BREAKER for me now
I will wait until the problem is solved.
#23
In reading this I cannot comment on the sound being described. However, I feel that some of what I see being described may be drivetrain 'lash' where the engine/transmission moves on the rubber mounts or subframe. This effect would be greatest in low gears where torque multiplication is the highest.
In the end, it's an automated manual transmission. When the clutch bites, I don't see how you cannot expect to 'feel' something. I would imagine that any software update would slow the shifting down, I'd be careful what you wish for.
Edited to add to the OP:
Are you describing the rev matching feature? As you slow, the transmission should be moving into a lower gear, to smooth out shifts, the throttle should 'blip' a bit to match the revs. It's what I (a manual driver) do when coming to a stop.
In the end, it's an automated manual transmission. When the clutch bites, I don't see how you cannot expect to 'feel' something. I would imagine that any software update would slow the shifting down, I'd be careful what you wish for.
Edited to add to the OP:
while I try to brake the engine is rev up and feels want to jump forward
Last edited by Colin; 09-09-2014 at 11:12 PM.
#24
Pro
Am I the only one who identified his description as the transmission merely downshifting as he decelerates...?
He cuts speed, tranny goes down a cog, this causes revs to increase, and he's feels the jerkyness of engine braking...
It sounds to me like the transmission logic doesn't know when he's braking to come to a peaceful stop vs braking like he's about to get back on the accelerator in a second. I thought the entire point of them ruining a dual clutch with a torque converter was to smoothen everything out for the luxury-oriented driver. I guess that isn't working out so well
The surge from N to D is normal and varies widely between cars based mostly on gearing and idle revs. If you give it enough brake, you shouldn't feel it.
He cuts speed, tranny goes down a cog, this causes revs to increase, and he's feels the jerkyness of engine braking...
It sounds to me like the transmission logic doesn't know when he's braking to come to a peaceful stop vs braking like he's about to get back on the accelerator in a second. I thought the entire point of them ruining a dual clutch with a torque converter was to smoothen everything out for the luxury-oriented driver. I guess that isn't working out so well
The surge from N to D is normal and varies widely between cars based mostly on gearing and idle revs. If you give it enough brake, you shouldn't feel it.
#25
Intermediate
I've had my I-4 for 3 weeks now and haven't noticed a thing. But I never drive in traffic, usually when driving my music is loud, when down and breaking quickly I can hear the car downshifting dramatically, which I like, never had it out of sports mode. I will pay more attention tomorrow. No problems accelerations from a stop or running through the gears - smooth as silk weather redlining or going easy. Just hit 600 miles.
#26
The TLX is a great car and I think this situation should be the unique problem of 8-DCT only. Hopefully the 9AT don't have the same problem, go for a test drive and you gonna love the car.
#28
Moderator
To clarify my personal experience - I've only had the slight jerk happen a couple times - both when I was coasting to a stop then tapped the gas to go again (at a light) - otherwise the sifts are so fast and so smooth you have to look at the tach to know they're happening.
I wonder if it wasn't in 2nd or 3d as I coasted and my tapping on the gas caused it to downshift into 1st or 2nd. Just a guess. Anyways - it's so minor that it's not even something I would bring up to the service people.
Also - I'm not getting any "bong" noise - or any noise for that matter.
Frankly you should be more concerned about the lack of exposed tailpipes
I wonder if it wasn't in 2nd or 3d as I coasted and my tapping on the gas caused it to downshift into 1st or 2nd. Just a guess. Anyways - it's so minor that it's not even something I would bring up to the service people.
Also - I'm not getting any "bong" noise - or any noise for that matter.
Frankly you should be more concerned about the lack of exposed tailpipes
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Stew4HD (09-10-2014)
#30
I must have expose tail pipe. That is one of the 2'reasons why I haven't bought a TLX yet. Waiting for some after market or someone to come up with something
The other reason is a discount I am a cheapskate that is why I drive Acura to begin
The other reason is a discount I am a cheapskate that is why I drive Acura to begin
#33
Not at all - IMO people are overreacting. This "problem" is simply a side effect of having so many gears...rather than the car shifting a gear every 10-15mph of speed increase/decrease, its doing it 5-10, much more often - therefore, in lower speeds - stop and go traffic, you'll notice more shifts as you speed up and slow down. I've seen it myself - the car doesn't do anything I wouldn't expect it to - it's still smooth, quiet, but sometimes like others have said, you press the gas to go, it makes it into the next gear then you brake to slow down or stop and it goes back down a gear. Not a problem...just more noticeable vs. straightaway open driving where it flies thru the gears up to 8 and you're cruising.
#34
Instructor
I've been really paying attention to my DCT the past couple of days. I have to say that I haven't technically noticed anything that I should be concerned about with mine....no real clunks, bangs, zonks, boinks, zaps or pows. I'm chalking it up to it being normal function in the car's determination of how best to maneuver through the 8 gears based on the driving circumstance. Overall, mine has been very smooth. Has it on occasion seem to too quickly engage a gear? Yes, it has. I think that is expected, tho. I'm trying not to focus on the gear shifting too much because I drove a Chevy Volt for the 2.5 years prior whereby I experience no gear shifting at all!
These are just my personal thoughts on it. I'm going to drive the car and enjoy it while I still have the new car buzz!
These are just my personal thoughts on it. I'm going to drive the car and enjoy it while I still have the new car buzz!
#36
Low and behold......
#38
#39
To clarify my personal experience - I've only had the slight jerk happen a couple times - both when I was coasting to a stop then tapped the gas to go again (at a light) - otherwise the sifts are so fast and so smooth you have to look at the tach to know they're happening.
#40
Lets all remember there is a difference between a "problem" and a behavior that is normal, even though it feels different than what we are used to.
I am a bit hesitant to call it a problem until more report the issue....
I am a bit hesitant to call it a problem until more report the issue....