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Discussion Starter #1
Hey guys,

So weird issue here and wanted to see if anyone else has this going on. I've got the 2018 Signature, bought it brand new earlier this year and since have 10k miles on it. I can count pretty much one hand how many times this has happened, so it's almost impossible to replicate, but when creeping through a parking lot at like 10-15mph, the car starts to buck back and forth - almost like the tranny can't figure out what gear it wants to be in

Using the paddle shifters force the gear doesn't seem to fix the problem, but I'm not really sure. It happens with such rarity, it's difficult to figure out specifically what is going on.

Any experience/thoughts on this?

Thanks guys
 

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Just as a data point I've got a 6 Signature purchased immediately upon arrival at my dealer in June, and with 2500 miles haven't experienced anything like you described. The first thing I'd check (just since it's easy to do and doesn't require replicating the problem) is whether you have the latest firmware installed.
 

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I've had my 6 Signature since end of May and just hit 2k miles and have not experienced this at all.

When this happens are you applying throttle or just coasting?
 

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I've noticed a slightly stumble/hesitation/jerky shifting when the transmission shifts into second gear at the lowest possible RPM, such as in a parking lot.

As for the bucking he claims - reminds me of something you would feel when driving a manual car in first gear.
 

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I have had his happen more than a few times. In the same low-speed situation where the car's transmission should be disengaging to let the engine idle freely of the transmission but it doesn't, it seems to hold on to it and it forces the car to try to keep from stalling. The sensation reminds me of when a manual transmission car's clutch needs to be disengaged because you're about to stall it.

Your are certainly not alone in experiencing this, Chazzy.
 

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Only have 2K but also have not experienced bucking. I typocally use paddles to keep the car in 2nd when I'm crawling.

Sent from my SM-N950U1 using Tapatalk
 

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I can't say that I've experienced that myself, but I'll keep this in mind if it ever happens to me...

Sent from my SAMSUNG-SM-G870A using Tapatalk
 

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I have the same exact problem. Mine is also a 2018 Signature, happen only after 3000 miles. Usually occur when I let go of the gas and let the car coast down to around 10-20mph at below 1000rpm, sometimes there's just a clunky noise sometimes it buck back and forth a little. Took the car to the dealership but technician couldn't duplicate the issue so service advisor told me to take note of the pattern when the issue happen the most and then take it back. Btw does anyone know if they will just reflash the software if I told them to or they must confirm the issue first?
 

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Discussion Starter #10
I'm pleased to see I'm not the only one with this issue.

Again, like 5 times in 10k miles is hardly something that can be replicated. Not a big deal to me, but I just wanted to make sure I wasn't the only one.

It's definitely on deceleration from like 20mph to 10mph as described by @Khai Ta.

Service manager is gonna do some research next week for me. More to come if he finds anything
 

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Just over 3K here and haven't noticed this.

Question: Does this typically happen when the engine is cold? Leaving a parking space after the car has been sitting.... Or does it happen when the engine is fully warmed up... during heavy traffic slowing down for a stoplight?
 

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This has not happened on my 18' Mazda 6 (yet), but it did happen to me one time in our 18' CX-9 (same drivetrain, 7,500 miles on it). Same situation. Two months ago I was driving about 8MPH on the street looking for a house number, I turned toward the curb, and it just started bucking like when you are in to high of a gear in a manual transmission car and need to push in the clutch. I stopped, and put it in park. Then put I it back in D and drove off. It was 70 degrees outside, vehicle was completely warmed up. We had been driving all morning. I think it may be one of those computer glitches, that are nearly impossible to replicate unless you are in just the right circumstances.

I would certainly mention it the next time you take it in for service, just to get it documented. This way Mazda will be notified of the issue, so their engineers can look into it if enough people mention it. As a technician myself, it drives me crazy when one of my systems is glitching, and I don't hear about it until months later. Someone will say, "oh that hasn't been working right for months," but no one ever tells me about it so I can't fix it.
 

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Not unique to the 2018, my 2015 has done it half dozen times, always at parking lot or stuck in traffic going less than 15 mph.
 

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Just over 3K here and haven't noticed this.

Question: Does this typically happen when the engine is cold? Leaving a parking space after the car has been sitting.... Or does it happen when the engine is fully warmed up... during heavy traffic slowing down for a stoplight?
Only happen when the car is completely warm up or have been driven for at least 5 mins and yes it happens the most during heavy traffic especially when slowing down to under 20mph and then accelerate again. Maybe that was why the technician couldn't duplicate the issue when I brought it in, forgot to tell him that.
 

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I've had this happen quite a few times.
2018 Sig with about 4000 miles.
For me it happens in traffic.
Crawling at 5-10 mph and taking my foot off the gas,
It's not terrible bucking, but I can feel it.
I'll talk to service when I get the first oil change and the AA/CP installed.
 

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This has not happened on my 18' Mazda 6 (yet), but it did happen to me one time in our 18' CX-9 (same drivetrain, 7,500 miles on it). Same situation. Two months ago I was driving about 8MPH on the street looking for a house number, I turned toward the curb, and it just started bucking like when you are in to high of a gear in a manual transmission car and need to push in the clutch. I stopped, and put it in park. Then put I it back in D and drove off. It was 70 degrees outside, vehicle was completely warmed up. We had been driving all morning. I think it may be one of those computer glitches, that are nearly impossible to replicate unless you are in just the right circumstances.

I would certainly mention it the next time you take it in for service, just to get it documented. This way Mazda will be notified of the issue, so their engineers can look into it if enough people mention it. As a technician myself, it drives me crazy when one of my systems is glitching, and I don't hear about it until months later. Someone will say, "oh that hasn't been working right for months," but no one ever tells me about it so I can't fix it.

I was wondering if it occurred in the latest CX9's drive-train too, so this answers that.
Thanks!
 

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When it happens, do you guys know if you had the transmission in normal automatic mode or in manual mode? I'm at around 5500 miles on my 2018 GT and I haven't felt anything resembling bucking yet on mine except for when I'm in manual mode and I've downshifted into 1st gear at anything over 10 mph. This car doesn't seem to handle this downshift as gracefully as my 2016 CX-3 did. Like it has a hard time doing the rev-matching well where the CX-3 was pretty brilliant at it. Another behavior I've noticed is that the car doesn't really do much engine braking while in normal automatic mode, but it will do it in manual mode if I force it into a lower gear than it thinks is optimal. I have encountered a couple times where it did feel almost like the car was about to stall when engine braking down to near a complete stop. I can't be sure, but in that situation, the engine may be giving it a squirt of gas to keep it from stalling, causing the sensation you're seeing. If it's the same thing I've seen, I'd call that feeling more of a shudder rather than a bucking sensation.
 

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Discussion Starter #18
Hi All,

Thanks for all of the responses. This is definitely helpful. Again, @Khai Ta seems to describe the issue perfectly and it looks as though others of you are experiencing.

My Service Manager is excellent at researching this stuff. While he may not find a solution or be able to replicate this, he'll search high and low and prod the right people to get some movement on this. Certainly more to come.
 

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When it happens, do you guys know if you had the transmission in normal automatic mode or in manual mode? I'm at around 5500 miles on my 2018 GT and I haven't felt anything resembling bucking yet on mine except for when I'm in manual mode and I've downshifted into 1st gear at anything over 10 mph. This car doesn't seem to handle this downshift as gracefully as my 2016 CX-3 did. Like it has a hard time doing the rev-matching well where the CX-3 was pretty brilliant at it. Another behavior I've noticed is that the car doesn't really do much engine braking while in normal automatic mode, but it will do it in manual mode if I force it into a lower gear than it thinks is optimal. I have encountered a couple times where it did feel almost like the car was about to stall when engine braking down to near a complete stop. I can't be sure, but in that situation, the engine may be giving it a squirt of gas to keep it from stalling, causing the sensation you're seeing. If it's the same thing I've seen, I'd call that feeling more of a shudder rather than a bucking sensation.

For me, it's in regular ol' automatic mode...no manual mode being used.
 

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It is very normal for skyactiv gearbox, and it is not an issue and happen always at low speed between 1st and 2nd gear when you cruise at that speed.
Our gear tries to lock all the time and this locking mechanism similar to manual gearbox.

Try this trick but not always, but your gear in manual and shift to 2nd from 0 speed, it will be smoother as the clutch will spool more and absorb more vibration but will increase the oil temperature.
 
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