Infiniti Q50 Forum banner
1 - 20 of 45 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter · #1 ·
There have been a few posts about how the braking force being applied to the Hybrid Q50 can fluctuate despite constant pressure on the brake pedal by the driver. I have experienced this a lot and it is very unsettling when taking an off ramp.

I reported this along with my DCU issue posted. And despite not being able to reproduce the issue the dealership is taking it seriously and so is Infiniti Engineering. Infiniti is sending a data logger to be installed in the car and when I feel the issue I will have a button to log the problem at the time it happens. This will be pretty cool, I am myself an electrical engineer and software developer so getting to help debug the car sounds like nerdy fun.

I will report back when I do record the issue but I wanted everyone else out there that they are not alone and it appears that Infiniti is hearing the issues are seem to be acting like they are committed to finding the problem and resolving it. So if you are having issues please report it so that if someone can get Infiniti to capture the problem we will all be able to get the thing fixed.

On a research expedition I did try my friends Prius to see what its brakes are like. Now they are not great but they are predictable and don't behave like the sporadic braking feel that I get in the Q50 so we should definitely help Infiniti get it right.
 

·
Registered
Joined
·
1,489 Posts
I wish you luck.

However, I've never noticed that braking phenomenon on ramps, but often when rotors are cold. Perhaps, it's because I usually shift to manual mode, on ramps. Anyway, I do hope you're able to help. But, why didn't Infiniti fix this before production?

Anyway, I did the data logger thing on my first SHO. Check Engine light came on and off by itself. They never figured it out but replaced the oxygen sensors, and the problem disappeared. They speculated that the sensors were only marginally within specs.
 

·
Registered
Joined
·
573 Posts
I feel it when coming to a complete stop, it pulses the last few seconds of the stop, like it is trying to switch between charging and powering related to the EV while stoping the last 20-30 feet. It is difficult to come to a slow smooth stop, easier to modulate with later braking and easing up before a complete stop. Hard to explain, but if you have a hybrid, you know what I mean.
 

·
Registered
Joined
·
19 Posts
I read about this in the MotorTrend review. They hammered Infiniti on this as they claim they did a poor job with the transition between normal braking and regeneration...

Here is their quote..."The brakes are one issue. Though they obviously stop the car well enough (our 60-0 mph braking test proves that), the Q50S Hybrid's brakes exhibited some of the worst pedal feel we've experienced since the first-gen Toyota Prius. The handoff from regenerative braking to mechanical braking is incredibly abrupt, with the brakes seemingly not slowing the Infiniti down in regenerative mode before quickly engaging in mechanical mode, throwing the car forward on its front wheels. Testing director and dynamics guru Kim Reynolds summed up the brake transition woes quite well: "Basically, their crazy initial bite renders the car unacceptable. I'd hate to be a passenger in this car in city traffic." As senior features editor Jonny Lieberman put it, "Performance hybrids require performance brakes"
 

·
Registered
Joined
·
1,273 Posts
After 4 months of driving and about 7200 miles on my Q50S hybrid, what I notice is this:
It's somewhat difficult for me get to a smooth stop on cold weather or when the brake pads and rotors is cold.
It's easier to get to nearly smooth stop when the weather is warm/hot or the brake pads and rotors already warm up.
It's more predictable when you slow down and goes into EV mode and slowly modulate the brake to get to a somewhat smooth stop.
The braking can goes havoc when you accelerate and brake when the gas engine suddenly transition to EV mode.

Hopefully, Infiniti engineer will figure it out and make the Q50 hybrid brake more predictable and smoother when come to a complete stop. The Q50 hybrid is an awesome car and truly a class of it own when it come to price, performance and technologies.
 

·
Registered
Joined
·
1,610 Posts
I feel it when coming to a complete stop, it pulses the last few seconds of the stop, like it is trying to switch between charging and powering related to the EV while stoping the last 20-30 feet. It is difficult to come to a slow smooth stop, easier to modulate with later braking and easing up before a complete stop. Hard to explain, but if you have a hybrid, you know what I mean.
I had a week off from the rush hour traffic and was back in the soup today and noticed this on the way home again in bad rush hour traffic.
The problem with rush hour is sometimes you have to brake hard (and/or have a bit more jerky stopping) and to me it seems to exacerbate the problem.
Where as when not in rush hour you can predicatively stop and modulate the breaks smoothly.

So ye in general keep on chirping.

If they can smooth this out, this is a great hybrid.
 

·
Registered
Joined
·
236 Posts
It's somewhat difficult for me get to a smooth stop on cold weather or when the brake pads and rotors is cold.
It's easier to get to nearly smooth stop when the weather is warm/hot or the brake pads and rotors already warm up.
It's more predictable when you slow down and goes into EV mode and slowly modulate the brake to get to a somewhat smooth stop.
The braking can goes havoc when you accelerate and brake when the gas engine suddenly transition to EV mode.
Ditto on the above. Fantastic that Infiniti is taking this seriously. Once they fix this and DAS cold weather issues <I've had no problems>, this will be one sweet ride.

Just some quick feedback about cold rotors/pads. I don't think that's the issue. Next time you drive while cold and experience grabby brakes, put it in neutral and brake. When in neutral, only the friction brakes are in play. You'll notice they are NOT grabby <at least that's my experience>. Today (6 deg), I noticed it took a long time for the car to go to EV mode. When not in EV mode, both the regen and V6 transmission are slowing the car (as well as friction brakes). So - I think what is happening at startup/cold weather when you brake is
(1) regen braking (nonlinear)
(2) lurching transmission drag/downshift (since not in EV mode when cold)
(3) friction brakes (smooth)

Just some things to experiment with.
 

·
Registered
Joined
·
1,273 Posts
What make you think the Q50 hybrid braking is not safe?
I had driven over 7300 miles on my Q50S Hybrid and never occur in my mind that I am in danger in any situation even at high speed braking.
In matter of fact, the braking power of the Q50S Hybrid brake is quite impressive due to those big brake. My other car Lexus ES350 brake very smooth, but it doesn't inspire the confident of braking power of my Q50S Hybrid.

That doesn't sound safe at all!
 
  • Like
Reactions: avanti5010

·
Registered
Joined
·
4,279 Posts
I have totally noticed the non-linear braking. I took it as just a little bad with the good for a car that turns braking into recovered energy. I came from a G37S coupe 6 MT. You have to expend some effort for the benefit of a manual to get a smooth ride. I look at the hybrid the same way. Just add a little finesse.
 

·
Registered
Joined
·
1,610 Posts
Sporadic breaking doesn't exactly instill any level of confidence. But that's just me.
When you say sporadic you make me think you hit the brakes the sometimes the car doesn't stop.

It's not like that.

There are a few problems.

1) It's noticable when the regen brakes grab when you take your foot off the gas. It doesn't cause you to come to a stop or anything like that, but the overall action seems like it can be smoothed out.

2) When the regen brakes pull off when comming to a stop it's nocicable. Similar to point 1 above, this needs to get smoothed out.

3) When comming to a stop, if you modulate the brakes to hard you can get a lurch type effect. I think this is a combination of things. For starters point 2 above where the regen brakes comes off. The overall sensativity of the pedal needs work. It's to sensative to modulation when comming to a stop. And lastly it might also be because the electric motor produces more low end torque at slowing speeds from 10MPH - 0MPH compared to a gas motor that is idling. At times it feels like your driving a gas engine that is in it's fast idle stage so it's pumping out more power than normal when you brake.
 

·
Registered
Joined
·
1,273 Posts
I had driven my Q50S hybrid with passengers in my car and none complaint about my braking. Perhaps, it is something I do right.
What I learn that if I am in EV driving mode and brake before coming to a complete stop; I can brake somewhat smooth. Not 100% smooth, but enough not to feel the tension.
I used two driving mode, Standard and Personal(Sport transmission) setting. On Standard mode, it is strictly for normal driving and I put it into EV mode any opportunity I can. Since the Q50 learn your driving habit and try to predict your driving behavior, it know that whenever I lift my foot off the gas pedal it goes into EV mode immediately. I always give a good distance before I come to a complete stop. You can modulate the brake pressure to get to a somewhat smooth stop once you are in EV mode.
 

·
Registered
Joined
·
1,610 Posts
I had driven my Q50S hybrid with passengers in my car and none complaint about my braking. Perhaps, it is something I do right.
What I learn that if I am in EV driving mode and brake before coming to a complete stop; I can brake somewhat smooth. Not 100% smooth, but enough not to feel the tension.
I used two driving mode, Standard and Personal(Sport transmission) setting. On Standard mode, it is strictly for normal driving and I put it into EV mode any opportunity I can. Since the Q50 learn your driving habit and try to predict your driving behavior, it know that whenever I lift my foot off the gas pedal it goes into EV mode immediately. I always give a good distance before I come to a complete stop. You can modulate the brake pressure to get to a somewhat smooth stop once you are in EV mode.
+1. Same for me.

It's really only an annoyance in rush hour traffic because you don't have predicable stops in stop and go traffic.

When you think it about it, this is a bit of an oxymoron.

Stop and go traffic is where the EV mode is kick ass and saves you a ton of gas mileage because it will get through most of it in EV mode, but where the brakes are the worst.

My bet is inifinit longer term is working on smoothing all this out.
The prius had this problem when it first came out and they got it sorted.
 

·
Registered
Joined
·
1,273 Posts
Actually, stop, go and slow moving traffic is easier for me to brake because I can mostly drive in EV mode in those condition. One time, I was managed to get 233 EV miles in a single tank of gas thanks to traffic of course.

Stop and go traffic is where the EV mode is kick ass and saves you a ton of gas mileage because it will get through most of it in EV mode, but where the brakes are the worst.
 
1 - 20 of 45 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top