Motor Shudder When Stopped ?

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danpatgal

Well-known member
Joined
Feb 27, 2012
Messages
202
Location
Ephrata, PA
A few times now I've noticed a very slight vibration/shudder in the motor when stopped at a traffic light - as if the motor's trying to go. It seems to happen if I have my foot planted lightly on the brake pedal initially. But, it's kind of unnerving and it's not happening upon start or if I let up at all on the brake, just if I'm using a light to medium pressure on the brake pedal (I've gotten into the habit of mashing the brake when stopped to prevent this phenomenon).

Has anyone else noticed this kind of shudder when at a stop? Am I just being picky, or is this something that should be fixed? It seems to me if I have my foot on the brake, no matter how lightly, no power should be going to the motor - and that doesen't seem to be the case sometimes.
 
I've noticed it also. I would guess it's a normal phenomenon.
I agree that no power should be going to the motor even with the slightest brake pressure. Maybe a software adjustment is needed?
 
I've noticed it when my foot is very light on the brake. Don't consider it to be an issue. It's the different nature of an electric motor vs an ICE.
 
fjpod said:
It's the different nature of an electric motor vs an ICE.
It's due to the manufacturer building an EV which too closely mimics an ICE powered car with an automatic trans - There was no really good reason to introduce the 'creep mode' in the first place. They could have/should have made it where it coasts to a stop when you release the go pedal . . . . like an ICE with a manual trans does when you push in the clutch

Don
 
I don't think so - If they wanted it to not roll backwards when you release the brake pedal on a hill, they could have easily done that without a creep mode . . . . no need for it to drive itself forward (or backward, since it does this in reverse as well) and force you to use the brakes to prevent it from moving when you don't want it to . . . . exactly like an ICE with an auto trans.

Letting it roll backwards wouldn't be bad anyway - Manual trans cars do and not letting them roll backwards is a somewhat tricky (for some) 'ballet' between the accelerator and the clutch pedals. Millions of us have mastered the technique of taking off without letting the car roll just fine - Simply taking your foot off the brake and putting it on the accelerator is simple enough that even auto trans drivers could master it I think - No clutch to deal with

You're stuck with this unwanted creeping behavior with ICE powered cars because you have an engine running all the time and a liquid coupler (the torque converter) which you cannot completely cancel. I'm all for keeping any good features that an ICE car has when you design an EV from scratch, but I'm also all for getting rid of all their useless, wasteful features since you're designing a new technology from a clean sheet of paper. We don't have an auto trans, no conventional 'transmission' at all really, so why would you stick an auto trans like 'shifter' console in an already cramped cockpit for everyone to bang their knees on? We have nothing to shift, so why do we have a shifter? Why pretend the car has an auto trans?

Don
 
Don said:
.. so why do we have a shifter? Why pretend the car has an auto trans?
Yes, why not a "shifter" like in the Prius, something rather small and simple up on the dash out of the way and then have paddles on the steering wheel for regen strength?

By the way, does anyone know if there is a formal way Mitsubishi is capturing these improvement suggestions for future models of the car? I know we have it on this forum, but it sure would be nice to know if there is an official list at Mitsubishi onto which customers can submit suggestions.
 
I think they tried to make the experience as comfortable as possible for drivers of gas engine cars. And I think that was a good idea. The way the car is currently configured made the switch to an EV very simple and straightforward. I for one am not a fan of the prius. I drove a friend's prius (first or second model, I can't remember which) about a month before buying my MiEV and I hated it. It took me forever to get used to all the controls and dashboard. Talk about a learning curve.
 
I wasn't suggesting they imitate a Prius either - The i isn't a hybrid any more than it's an ICE. Still, a small lever on the dash could engage Park . . . . or better yet, let the keyswitch do it with a solenoid . . . . you have to have your foot on the brake to start the car, so let that simple action take it out of Park at the same time

We had pushbuttons to select transmission modes nearly 100 years ago . . . . and those actually mechanically changed the gear selector in a transmission - Surely on a car which has no gear selector at all we could have had a simple button to select the software to be used in the driving mode, as opposed to imitating an auto tranny shifter?

I don't see how imitating what you're trying to replace could ever be considered a good idea - When you have a better product, let everybody else try to imitate you!

I understand what you're saying too Tony - They probably mistakenly thought soccer mom's were going to be their main market, but I'll bet even they would be a bit disappointed that such a high tech car wasted so much time and money trying to imitate low tech

Don
 
Since the gear selector cable just moves an electric switch, I'd bet that adding pushbutton controls would be quite doable (if not changing functionality, just duplicating or relocating the control). There are four-channel add-on steering wheel-mounted controls available, but using radio frequency controls for gear changes would take a leap of faith.. :? . A wired control connection would also be straightforward if not mounted on the steering wheel.
 
I also think they made the design to imitated an ICE

The creep to imitate an automatic transmission ,
The floor shifter to comfort the ice driver with things familiar
The gas gauge imitation

They tried to make the transition for the masses from an ICE to an EV with as few differences & inconvenience as possible

My wife's first comments were how easy the car was to drive.

I would like to see a sportier coupe version of the Miev with paddle switches on the steering wheel as well appealing to the younger drivers.
 
danpatgal said:
no power should be going to the motor - and that doesen't seem to be the case sometimes.

Here's my theory on this.

When you press the brake pedal to the 2nd switch position, it cuts the power to the motor and so the motor retracts some and then the magnets take effect and fight for the nearest opposing pole.
 
Wee John said:
Here's my theory on this.

When you press the brake pedal to the 2nd switch position, it cuts the power to the motor and so the motor retracts some and then the magnets take effect and fight for the nearest opposing pole.

That's been my observation as well.
 
The motor fighting for a pole kind of makes sense. I've actually noticed this shudder more when I stomp on the brake vs. just holding it only as hard as I need to to stop. I suppose it's too much to ask the electronics to essentially put the car in neutral when the brake is pressed. I wonder if other EVs have this same issue.
 
danpatgal said:
A few times now I've noticed a very slight vibration/shudder in the motor when stopped at a traffic light - as if the motor's trying to go. It seems to happen if I have my foot planted lightly on the brake pedal initially. But, it's kind of unnerving and it's not happening upon start or if I let up at all on the brake, just if I'm using a light to medium pressure on the brake pedal (I've gotten into the habit of mashing the brake when stopped to prevent this phenomenon).
I've noticed this too - I *think* it's caused when a light pressure on the brake causes the second switch to engage/disengage the idle power to the motor and then the ultra soft motor mounts allow the motor to shake the car

The motor mounts are really soft, as Wee John documented for us in this video
http://www.youtube.com/watch?v=XuR4AHUFrEE

Don
 
Interesting video. I never thought I would watch a 4 minute video of that type with such interest. :lol:

When stopping my car, I thought it was the light brake pressure I used to stop the car (I always drive in "B" mode), and the "parking lot creep" was fighting the light brake pressure. All I do is put a little more pressure on the brake when I'm completely stopped.
 
aarond12 said:
Interesting video. I never thought I would watch a 4 minute video of that type with such interest. :lol:

When stopping my car, I thought it was the light brake pressure I used to stop the car (I always drive in "B" mode), and the "parking lot creep" was fighting the light brake pressure. All I do is put a little more pressure on the brake when I'm completely stopped.

Just an FYI, the extra pressure on the brake pedal turns off the 'creep mode'. There's a lot of functionality in our brake and amp pedals.
 
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