Transmission Lurches When Downshifting

J

jimBean

:
2014 Mazda 3 Sport GS
Hey,

I was wondering if anyone else is experiencing this: when my 2014 GS AUTO downshifts (especially when coasting) I feel the car lurch slightly - almost as if the its shifting early and engine braking. I've taken it to the dealership and they were very hesitant to admit that it was a fault and were trying to tell me that it was potentially normal behavior, although they were happy to make a ticket with Mazda if I wanted. I don't remember any of the demo's driving like that and was wondering if anyone here had been experiencing something similar? I've also only got 600KM on the vehicle so was also hoping it might go away as the car continues to break in. Thoughts..?

Thanks,
Jon
 
I think it's engine braking, I only notice this when I let off the gas and let the car coast, it'll do it around 21mph and 13mph. Just feels like a sudden stop or something like that. It was more noticeable when I first got the car but now it seems not as abrupt or maybe I'm used to it lol I got about 2700 miles on mine now. My previous car does that too just not as abrupt as on the 3 so I didn't think much of it.
 
Thanks for your thoughts. I'll ride it out for a few more miles to see what happens, but right now it's pretty noticeable.
 
Keep in mind that for all intents and purposes, there is no torque converter. Everything's directly and physically connected in that drivetrain above about 5 MPH, so it's going to feel more immediate than in a traditional automatic, with the torque converter absorbing some of the harsher aspects of downshifting.
 
npaladin2000 said:
Keep in mind that for all intents and purposes, there is no torque converter. Everything's directly and physically connected in that drivetrain above about 5 MPH, so it's going to feel more immediate than in a traditional automatic, with the torque converter absorbing some of the harsher aspects of downshifting.
Click to expand...

From my understanding, there still is a torque converter(TC). It is just that the TC has been revised so that the lockup ratio is up to 80% from normal 50% of the times. It is a different design, and a better one. However, saying there is no TC is a bit off.
 
That's why I said "for all intents and purposes, there is no torque converter." The thing isn't even used above 5 MPH, my understanding is that it's locked out completely (I might be wrong, the number might be 10 MPH). Hence, it may as well not be there except at very low speeds. Downshifting above that range is going to be harsher because there isn't a torque converter damping things out and insulating the driver from the drivetrain. Which is a small tradeoff given how wonderful the transmission is, but it does need to be made clear that the TC in the SkyACTIV Mazdas does very very little outside of damping out low-speed harshness (which is where Ford had massive problems with their DCT, incidentally, and is probably why Mazda didn't go DCT).
 
From what I have read as well, the TC is only used at low speeds, probably around 0-10 mph. After that it operates like a manual transmission (albeit without the stick shift)
 
The more I think about it. I think we are feeling the difference of the high compression engine. I did not notice it much until I read it here. I drove several 5.0 mustangs in the past with high compression setups and you can feel the drag of the motor when decelerating.

Have you ever started some of the new easy start chainsaws? The way they make it easy start is the first rotation is a non compression stroke. Something opens up to make it have less compression until it starts.
 
I feel the downshift in mine while coasting to a stop. Way more noticeable than any other car I've driven. Doesn't really bother me. I think it's normal for the reasons others have stated.
 
rvoll said:
What is occurring is part of the SkyActiv technology. Engine braking actually decreases mpg. So Mazda has programmed the auto to "freewheel" at some downshifts where the engine would be at high rpm's and engine braking would decrease mpg.
Click to expand...

How does engine braking decrease mpg when the fuel injection system completely cuts/stops injecting fuel when you release the gas pedal, until the engine speed approaches idle? (where is your reference on this?) By using engine speed to brake with, it reduces brake wear, it increases gas pedal effect for a more direct control feel, if equipped it allows the iloop high capacity alternator to charge up the capacitor increasing engine braking. The energy stored in the capacitor is used to increase mpg... I believe that it does not downshift at high rpm to reduce the lurch but if you are in a lower gear and release the gas pedal it will not upshift but hold the gear and the rpm.
 
I don't know that this is what rvoll was referring to, but greater engine braking could lead to slightly worse fuel efficiency due to the fact that the car will not coast as far, so you will have to be on the gas longer/later. I noticed this when going from my 2012 Focus to the new Mazda3. I could coast forever in that Focus, so the fuel cutoff lasted longer than what I find myself doing in the Mazda3. I can't imagine it amounts to much of my average gas mileage, though.
 
jimBean said:
Hey,

I was wondering if anyone else is experiencing this: when my 2014 GS AUTO downshifts (especially when coasting) I feel the car lurch slightly - almost as if the its shifting early and engine braking. I've taken it to the dealership and they were very hesitant to admit that it was a fault and were trying to tell me that it was potentially normal behavior, although they were happy to make a ticket with Mazda if I wanted. I don't remember any of the demo's driving like that and was wondering if anyone here had been experiencing something similar? I've also only got 600KM on the vehicle so was also hoping it might go away as the car continues to break in. Thoughts..?

Thanks,
Jon
Click to expand...

This! Ok, I thought I was just crazy, but this has been happening to my new 14' Sport as well. I've been panicking a little because I just came from a 2013 Ford Fiesta ( don't judge me ) that had a faulty transmission. Ended up dumping that car and going to this one, but have noticed the "lurching" when I'm coasting, or in lower gears. I tend to only really notice it when I'm in stop and go traffic, and this is the first Mazda I've owned so I was chalking this up to being a different beast than what I've been driving.

I have less than 1k on it, so I'll give it to maybe 2k and get more of a feel for it, but I'll be interested to see if anyone else posts with this issue.
 
Nothing wrong with the Fiesta! It's a great little car for the most part. Just needs some steering feel. I test drove one when my 2005 Mazda3 died. It was too narrow inside, but the real deal breaker was the totally numb steering. Ford fixed that with the Fiesta ST, which supposedly has good steering feel. That car's getting all sorts of fantastic reviews from the enthusiast magazines.
 
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