Sloppy transition from accelerating to coasting

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Old 06-06-2020, 08:20 AM
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Sloppy transition from accelerating to coasting

This is a very subtle thing and difficult to describe. I'm noticing this around town and not so much a highway speeds. I have AWD.

When lifting your foot off the gas and transitioning from accelerating to coasting, does anyone else notice a soft "bounce" in the driveline? It's a short, quick rocking as if the car has flex or looseness in the driveline. The transition isn't solid.

If you have ever felt the play in gears that don't mesh tightly, it feels like that is happening. Engineers call it "lash". I wouldn't be surprised if it's caused in some way by the electronic AWD.

I have never noticed this in other cars, including AWD. It's not serious or worthy of a service call, but curious if anyone else has noticed this.

Last edited by DJA123; 06-06-2020 at 08:23 AM.
Old 06-06-2020, 08:30 AM
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Nope, can't say I've noticed such a thing.

The only odd thing I've noticed about the tranny is when the car is stone cold and I put it in reverse the first time. I feel and hear at least three distinct mechanical transitions that take 1-2 seconds to complete. All the drive-by-wire components actuating in series, just from the press of a button. I thnk many here are bothered by it more than I am.
Old 06-06-2020, 08:46 AM
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Originally Posted by NooYawkuh
Nope, can't say I've noticed such a thing.

The only odd thing I've noticed about the tranny is when the car is stone cold and I put it in reverse the first time. I feel and hear at least three distinct mechanical transitions that take 1-2 seconds to complete. All the drive-by-wire components actuating in series, just from the press of a button. I thnk many here are bothered by it more than I am.
I'm doubtful that it's registered with anyone. Even if it is present in other cars, you'd likely have to be consciously looking for it. The more abrupt the lift off the gas, the more noticeable. A slow lift and I don't feel it.

Thanks
Old 06-06-2020, 11:17 AM
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Are you sure you aren’t feeling a downshift? I’ve noticed the car doesn’t coast well, and others have suggested it’s actually downshifting to be ready to accelerate when needed.
Old 06-06-2020, 11:28 AM
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Originally Posted by Waetherman
Are you sure you aren’t feeling a downshift? I’ve noticed the car doesn’t coast well, and others have suggested it’s actually downshifting to be ready to accelerate when needed.
Nope, not the downshift. I can avoid it by easing up on the gas slowly. It's definitely a little shudder in the driveline when quickly reversing the load. It's not significant, but enough that it grabbed my attention once and I notice it now.
Old 06-07-2020, 01:28 AM
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Originally Posted by DJA123
This is a very subtle thing and difficult to describe. I'm noticing this around town and not so much a highway speeds. I have AWD.

When lifting your foot off the gas and transitioning from accelerating to coasting, does anyone else notice a soft "bounce" in the driveline? It's a short, quick rocking as if the car has flex or looseness in the driveline. The transition isn't solid.

If you have ever felt the play in gears that don't mesh tightly, it feels like that is happening. Engineers call it "lash". I wouldn't be surprised if it's caused in some way by the electronic AWD.

I have never noticed this in other cars, including AWD. It's not serious or worthy of a service call, but curious if anyone else has noticed this.
how many miles are you at? May be the torque converter unlocking
Old 06-07-2020, 02:02 AM
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This AWD drivetrain has three linked driveshafts going to the rear differential, each of which has universal joints. And there are hypoid gears at the front transfer case and the rear differential. That's a lot of places to have some play. It's probably not your imagination, but it's probably not abnormal.

I've owned a lot of 4WD/AWD vehicles, and they all have a little bit of lash in the drivetrains, especially as they age. Nature of the beast. Only way around it would be electric, like Acura sport hybrid, but that has its own issues.

Aside from drivetrain lash, another thing you might be feeling is engine movement. The fancy engine mounts are designed to minimize vibration transmission, and I believe they are the active counter-vibrating ( ACM ) kind, but they aren't rock hard. Some engine movement is to be expected.
Old 06-07-2020, 06:33 AM
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Originally Posted by DJA123
Nope, not the downshift. I can avoid it by easing up on the gas slowly. It's definitely a little shudder in the driveline when quickly reversing the load. It's not significant, but enough that it grabbed my attention once and I notice it now.
I spent a few hours in the car yesterday and tried to see if I could feel what you’re describing, but didn’t. Either I’m not as sensitive or it’s something that happens in some cars but not others. If the latter, maybe it can be fixed.
Old 06-07-2020, 07:19 AM
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You sure this is not from transmission downshifting? It could be a little harsh when car has low miles...
Old 06-07-2020, 08:44 AM
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Originally Posted by Dereileak
how many miles are you at? May be the torque converter unlocking
Only 1500mi

Originally Posted by Wander
This AWD drivetrain has three linked driveshafts going to the rear differential, each of which has universal joints. And there are hypoid gears at the front transfer case and the rear differential. That's a lot of places to have some play. It's probably not your imagination, but it's probably not abnormal.
.....
Aside from drivetrain lash, another thing you might be feeling is engine movement. The fancy engine mounts are designed to minimize vibration transmission, and I believe they are the active counter-vibrating ( ACM ) kind, but they aren't rock hard. Some engine movement is to be expected.
This all makes sense.The engine mount point is definitely something I was thinking too. It's that same rubbery feeling as loose engine mounts, but MUCH smaller effect. The transition has that secondary movement.

Originally Posted by Waetherman
I spent a few hours in the car yesterday and tried to see if I could feel what you’re describing, but didn’t. Either I’m not as sensitive or it’s something that happens in some cars but not others. If the latter, maybe it can be fixed.
Yeah, it's subtle at best, and arguably a little finicky. But it's not nothing. It's fair to say this falls within the vagaries of a mass produced product. Some people get a bigger door gap; some get seat mount that rocks; I got some sponginess in the driveline. As long as it doesn't get worse, I'll live with it.

Thanks
Old 06-07-2020, 09:40 AM
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I know what DJA123 means. I feel that too with my car. But I interpret it differently. I feel the car only coast completely at lower speed range, maybe <30mph. At higher speed range, there is more drag when coasting, and there is a slight "play" when lifting off throttle. To me it feels like more like something is disengaged in the powertrain.

If your feel your car is doing that too much, try the throttle sensor reset sequence. (See my Hondata thread, or it was mentioned in KTuner thread as well). It should help smoothing out the transition.
Old 06-07-2020, 10:50 AM
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Originally Posted by sonyfever
... there is a slight "play" when lifting off throttle. To me it feels like more like something is disengaged in the powertrain.
...
Yep, it may be down to variations in assembly precision. Some get more than others. I'm willing to accept it as it is now.
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