Car Jiggles After 30 Sec At Stoplight

I have a 21 Mazda CX-5 Grand Touring Reserve. When I have the A/C on and sitting at a stoplight the engine increases RPM when the compressor engages. If you don’t have your foot on the brake pedal hard enough it will make a slight surge forward when the RPMS increase. My car has the Turbo. I am light on the brake when a stoplights I guess because if you aren’t light on the brake I bet you wouldn’t even notice this.
 

Pitter

Pitter
Contributor
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2020 CX-5 Signature Azul Metalico
Good point. I generally set the brake to "hold" so I won't have to press down on the pedal after setting it. We have some long lights.
 
My wife loves the brake hold on her HRV. I never use it because I’m afraid I will accidentally bump the gas pedal and take off when I don’t mean to. I wonder when you use brake hold how much pressure it holds on the brakes? Is it like a light footed person or with more pressure then that? So if it is light I wonder if you could get that surge when the A/C compressor kicks on and the RPMS increase.
 
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2020 CX-5 Sig
Has anyone that experienced this subtle jolt/jerk/bump/lurch/shudder had it checked out?

I'm experiencing something I think is similar as to what is being described here on my 2020 CX-5 Sig. After coming to a stop at an intersection I hear this faint thump/pop from the back that feels like a downshift or something disengaging or even a muffled detonation. Could almost mistaken it for a loud bass thump. I can't replicate it at every stop but I hear and feel it at least once on every trip. The sound is too faint to be recorded with a cellphone but the vibration can certainly be felt. I don't even know how to describe it to the dealership.
 
I have a 21 Mazda CX-5 Grand Touring Reserve. When I have the A/C on and sitting at a stoplight the engine increases RPM when the compressor engages. If you don’t have your foot on the brake pedal hard enough it will make a slight surge forward when the RPMS increase. My car has the Turbo. I am light on the brake when a stoplights I guess because if you aren’t light on the brake I bet you wouldn’t even notice this.
Same forward motion with minor Rpm, maybe an inch forward movement with my old 2008 Civic Lx when A/C is on at a stop light few times (my foot has not all the way down the brake pedal) but not on my 2021 CX-5 gtr yet with 650 miles (hopefully no jinks lol).
 
I’ve felt this in my 2019 since taking ownership. When using the HOLD feature I don’t notice it, but at a light randomly it feels like someone bumped me/gear downshift/ gas sloshing in tank/let off brake for a split second/ etc type of slight jar.

It’s never gotten worse so I just attributed it to an odd but non problematic nuance of the car.

Could even be something with the AWD system (transfer case?), which is a good question. Are there any FWD versions which have this jar occur?
 

AVC

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'17 CX-5 Select
So, I know EXACTLY what causes this "did someone bump me" thing, as I caught it in the act this evening. When the A/C compressor runs, the throttle is opened a tad farther to compensate for the increased load and raises the RPM to about 750 (from about 550) for more compressor output. The "bump" occurs when the HVAC head unit releases the compressor clutch and the engine PCM is a fraction of a second tardy closing the throttle back down, resulting in a quick surge in RPM--too fast for the tach needle to move much. It does this only on a small number AC compressor cycles (only once in a commute with 6 stops lights), so don't know if the PCM is caught flatfooted sometimes and doesn't promptly process the "disengaging compressor now"message or what.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
So, I know EXACTLY what causes this "did someone bump me" thing, as I caught it in the act this evening. When the A/C compressor runs, the throttle is opened a tad farther to compensate for the increased load and raises the RPM to about 750 (from about 550) for more compressor output. The "bump" occurs when the HVAC head unit releases the compressor clutch and the engine PCM is a fraction of a second tardy closing the throttle back down, resulting in a quick surge in RPM--too fast for the tach needle to move much. It does this only on a small number AC compressor cycles (only once in a commute with 6 stops lights), so don't know if the PCM is caught flatfooted sometimes and doesn't promptly process the "disengaging compressor now"message or what.
I though only everything-mechanical carbureted engines in the old day are having such behavior?
 
I've experience the same in my '21 Signature, and tend to agree with AVC's observation that it's due to a slight lag between compressor clutch disengagement and the PCM reducing requested torque back down to normal idle. I believe that although this is less than ideal, it's the way it's programmed, as I've been able to identify it in multiple different CX-5s.

As also previously mentioned, the feeling is mitigated with a firmer application of the brake pedal, which reduces the movement making in much harder to discern. Auto hold also requires a firmer brake application before it will engage. With my normal driving manner, I have a light application of the brake at most stops, which requires an additional press for the Auto Hold to engage. As such, those who by default press harder on the brake pedal and/or activate Auto Hold may not have experienced this.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
I've experience the same in my '21 Signature, and tend to agree with AVC's observation that it's due to a slight lag between compressor clutch disengagement and the PCM reducing requested torque back down to normal idle. I believe that although this is less than ideal, it's the way it's programmed, as I've been able to identify it in multiple different CX-5s.
The problem to me is this behavior is not happening on my 2016 CX-5.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Please explain how it’s a problem that a prior generation vehicle isn’t exhibiting the same behavior?
Mazda redesigned and modified the engine、transmission、and even the exhaust system for cylinder deactivation, and the complaints on rough shifting started. Mazda should know where the problem is, not me. ;)

The problem to me is Mazda introduced a feature which is historically problematic, and even now is still having problems with endless TSBs coming out by Mazda.
 
Mazda redesigned and modified the engine、transmission、and even the exhaust system for cylinder deactivation, and the complaints on rough shifting started. Mazda should know where the problem is, not me. ;)

The problem to me is Mazda introduced a feature which is historically problematic, and even now is still having problems with endless TSBs coming out by Mazda
The original poster and several others of us in this thread all have the turbo engine without cylinder deactivation. The issue is not related to shifting. It seems you’re not on topic here and muddying the conversation.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
The original poster and several others of us in this thread all have the turbo engine without cylinder deactivation. The issue is not related to shifting. It seems you’re not on topic here and muddying the conversation.
My point is Mazda made some redesign and modification based on once-almost-perfect original SkyActiv-Drive 6-speed automatic transmission for both 2.5L with CD and the 2.5T, and the complaints started, no matter it’s subtle jolt/jerk/bump/lurch/shudder/rough-shifting. There’re several threads going on here for a while on this problem, and Mazda seems to find no way to cure it.
 
My point is Mazda made some redesign and modification based on once-almost-perfect original SkyActiv-Drive 6-speed automatic transmission for both 2.5L with CD and the 2.5T, and the complaints started, no matter it’s subtle jolt/jerk/bump/lurch/shudder/rough-shifting. There’re several threads going on here for a while on this problem, and Mazda seems to find no way to cure it.
There are trade offs in everything. As with every vehicle, I’m sure we can look back to the “almost-perfect” iterations and find plenty of complaints. The vast majority who experience no issues don’t come to a forum to post about it, and forums like this one, especially for non-enthusiast vehicles have very low activity these days. Just look at the CX-5 Recent activity aggregation and see how little activity there is on a daily basis.

There are also plenty of owners (of all products) who have a confirmation bias, and are compelled (consciously or subconsciously) to validate they made the right choice and their vehicle is simply great is every regard. Those along with those who are hyper sensitive about their purchase, and look for a problem in every aspect make up a significant part of forum posts. It’s not an accurate indicator of the vehicle overall quality and satisfaction.

I’ve experienced this “jolt” which I’d describe as just barely enough to notice and found that it’s alleviated by applying slightly more brake pressure. I didn’t feel it worthy of initiating a conversation, but shared my experience once I saw the post about it. Especially in modern vehicles, there is so much programming for every small function, that is developed separately. Yes, Mazda should do better testing pre-production, and yes they should solve issues much more quickly. That being said, as a recent purchaser and owner (my 28th car in 23 years of driving) I was and am willing to overlook the small software shortcomings of the car for the overall package, which is better looking, has better materials and design and drives better than the competition. I’m sure Toyota and Honda makes vehicles with fewer of these type of issues, but when the bigger factors aren’t as good, that’s not worth much to me.
 

erhayes

Contributor
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2021CX5 Reserve
Torque converter unlocking. It stays locked for sometime in case you want to immediately go after stopping. Good design in my opinion. Always seem to be some malcontents ready to jump on anything they don't comprehend or understand. Ed
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
There are trade offs in everything. As with every vehicle, I’m sure we can look back to the “almost-perfect” iterations and find plenty of complaints. The vast majority who experience no issues don’t come to a forum to post about it, and forums like this one, especially for non-enthusiast vehicles have very low activity these days. Just look at the CX-5 Recent activity aggregation and see how little activity there is on a daily basis.
I have been with this forum long enough and I haven’t seen these many subtle jolt/jerk/bump/lurch/shudder/rough-shifting complaints to the transmission before Mazda modified it. Especially in old days there’re more traffic here than right now. No, there’re very few complaints about jolt/jerk/bump/lurch/shudder/rough-shifting, only praising the smooth shifting to the transmission.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
:
Plano, Texas, USA
Torque converter unlocking. It stays locked for sometime in case you want to immediately go after stopping. Good design in my opinion. Always seem to be some malcontents ready to jump on anything they don't comprehend or understand. Ed
Torque converter with lock-up clutch, and it stays locked most of time are nothing new to Mazda’s SkyActiv-Drive automatic transmission and many others such as Toyota’s current 8-Speed Direct Shift automatic transmission. Had you experienced the same subtle jolt/jerk/bump/lurch/shudder/rough-shifting people are talking about on your previous gen-1 CX-5?
 
Torque converter unlocking. It stays locked for sometime in case you want to immediately go after stopping. Good design in my opinion. Always seem to be some malcontents ready to jump on anything they don't comprehend or understand. Ed
I'm not sure you should be criticizing other people for not comprehending or understanding, when you clearly do not understand how a torque convertor works. If a torque convertor was locked up at a stop, your engine would be directly connected to the transmission input shaft and the engine would be stopped, since the wheels aren't turning.

Torque convertors do not lock up at low speeds, and definitely not at anything approaching a stop. Historically this was limited to top gear and vehicle speeds above 35-40mph, but with more advanced computer controls, has expanded to engaging in multiple higher gears with lots of additional parameters such as fluid temperature, throttle position, etc. involved in the logic. But definitely no logic would have a torque convertor locking up at low speed or a stop.
 
Torque converter with lock-up clutch, and it stays locked most of time are nothing new to Mazda’s SkyActiv-Drive automatic transmission and many others such as Toyota’s current 8-Speed Direct Shift automatic transmission. Had you experienced the same subtle jolt/jerk/bump/lurch/shudder/rough-shifting people are talking about on your previous gen-1 CX-5?
Not sure why you keep trying to push this specific thread topic toward being a transmission related issue when several of us who actually experience the condition on our vehicles have identified specific non-transmission related factors that are consistently coinciding with the slight jolt being felt, and would absolutely cause this feeling.

I don't believe bringing up anything about a Toyota automatic transmission is adding to this particular discussion thread.