[DopplerEffect]

So, occasionally when I'm driving the DCT, whether in auto or manual, if I am on partial throttle and upshift, the gear will engage, but the revs will flare like the clutch is slipping. It's almost as if the car is making more power than the TCU expects, so it doesn't swap gears fast enough. Oddly, this problem immediately goes away when sport mode is activated. I don't know if it has anything to do with the TCU swapping gear sets faster or whatever. I just want to know if others have noticed this.

Problem:
Car's revs flare at partial throttle when shifting up gears past 3rd, only when shifting. After the flare, the gear is fully engaged and no clutch slip occurs.

When:
Engine and transmission are cold
Engine is hot and transmission is cold

 

[TheShaddix]

I get the same slippage too, but I think that's normal when it's not fully warmed up. Still not really sure what you mean by "flare" though.

 

[stephmorrr]

I get this too, but its really inconsistent.. when the cars cold it shift quick and grabs hard... Seems like it does it when I drive the car 50 miles or more, and when I short shift under mild power.. WOT It shifts like a dct should

 

[KDMSpecial]

I get this too, but its really inconsistent.. when the cars cold it shift quick and grabs hard... Seems like it does it when I drive the car 50 miles or more, and when I short shift under mild power.. WOT It shifts like a dct should

Maybe that's just its way of speaking to us, asking to be driven hard.

 

[DopplerEffect]

What I mean by "flare" is that it engages, then slips a tiny bit and re-engages (the revs jump a tiny bit right after a shift).
Also, she definitely doesn't do this when driving her hard. This car seems to just love it.

 

[TheShaddix]

I do have that same effect but it's on downshifts mostly. Like when you still have some throttle applied and drop gears, the car will take way longer to lock into gears and is really jerky. Or when you downshift (with throttle released), then try to apply throttle right away before it fully locks in, it just doesn't want grab and feels like it's still slipping the clutch for a brief moment. On the upshifts I have not noticed that much, but I'll try to keep my eye on this and see if I notice anything. I think as much as we want this DCT to be perfect, it'll just have its moments. I keep trying to compare it to that of bmw, but there is honestly no comparison beyond the technical facts. I think this is the best we can get at the price point. It's still way better than my previous lexus IS 8 speed. That thing took forever to downshift on the highway. This elantra is like a race car in comparison, at almost half the price.

The main reason, I think, is most likely that they kept the reliability factor in mind first and performance second. Hence you don't get those nice jolts when driving hard and shifting, and it still doesn't shift as fast as it could for being a dual clutch. I notice there is a tiny bit of lag from paddle pull to gear shift, but it's so negligible, almost not worth mentioning. The car chooses what's good for it in whatever situation. I actually noticed the car drives/shifts a bit better with all the traction and stability controls off when you're driving it hard (traction button held for 3+ seconds), but that applies only to full throttle shifts.

 

[jamesrayth]

I do have that same effect but it's on downshifts mostly. Like when you still have some throttle applied and drop gears...

This how DCT's work. Watch this:

 

[TheShaddix]

Great video! Thanks! Most things I already knew, but a few of the later points definitely make a lot of sense now.

 

[jamesrayth]

Great video! Thanks! Most things I already knew, but a few of the later points definitely make a lot of sense now.

Yeah I didn't understand how it chose gears until after that video, but definitely makes a lot of sense. Understanding that, I've found if I know I'm going to pass someone, I break, downshift one gear so I'm in turbo sweet spot, then gas it and upshift when needed. Makes a lot of difference.

 

[TheShaddix]

No wonder downshifts always seem a bit faster when you're breaking like driving up to a red light. If you're just cruising and have no throttle applied, at this point the car has no idea whether you wanna downshift or upshift next, so it has that very slight delay from paddle to shift. Understanding it is key to being happy with it! I am pretty sure most people with this dct still only drive in auto mode and only got the car like that because they didn't want a manual.

 

[TheShaddix]

Hey guys, I just noticed another issue (or quirk, to put it mildly) with the dct in this car. Everytime it downshifts it takes a second to actually lock into the gear. The response from shift paddle to gear change is more or less instant, but the actual time till you can use that gear is not as quick. For example, if I am in 4th (any rpm) and drop down to 3rd (with throttle released), then give it full throttle to take off, the clutch is not locked in yet so it feels like it's still slipping into place. This happens regardless of whether you're braking or just cruising. Is this normal for dct? Shouldn't it be immediately available? And is this part of that flare issue discussed earlier?

 

[jamesrayth]

Yeah its like the ECU is not rev matching properly, so it doesn't fully engage until you've given it some throttle. Hoping a tune fixes that.

 

[17ElantraSportPremium]

After a mountain drive yesterday, it felt like engine braking only happens after downshift WHILE braking. Only a little tap of the brakes makes it do so. Without touching the brakes, it's just more noise, higher revs. Aside: coming from a six speed auto with paddle shifters, remembering to down 4 times instead of three for certain curves is unnerving the first little while I was driving.

 

[Poolnoodle]

After a mountain drive yesterday, it felt like engine braking only happens after downshift WHILE braking. Only a little tap of the brakes makes it do so. Without touching the brakes, it's just more noise, higher revs. Aside: coming from a six speed auto with paddle shifters, remembering to down 4 times instead of three for certain curves is unnerving the first little while I was driving.

This engine doesn't brake for ****, I have to be at about 4K in my VT to even barely notice engine brake.

 

[kdetlor]

This engine doesn't brake for ****, I have to be at about 4K in my VT to even barely notice engine brake.

In that case you have to really to watch out for brake fade in long downhill runs and aggressive track runs.