Car rolls backwards uphill in D

dml105

Well-Known Member
Joined
Jul 26, 2020
Threads
23
Messages
906
Reaction score
1,348
Location
Arlington, VA
Vehicles
Shadowfax, the Star White Tricoated Metallic Pony
Country flag
So I’ve noticed a very worrying problem with my Mach-e that I’ve been able to replicate:

When coming to a stop at slow speed on a small hill, like coming to the end of a driveway with an apron, the car stops and then slowly rolls backwards when I lift my foot off the throttle. I’ve noticed this at least four times. It’s always slow speed, but that’s still no good as you’re not looking in reverse when you’re in drive.

Today, I came inches from hitting a very pissed off pedestrian crossing behind me at a very busy intersection.
Other factors: one pedal mode with hill assist and reverse braking assist on.

Anyone else notice this in their cars?

EDIT: note- this happens when the car is pointed DOWNHILL on the apron, and rolls backwards UP the hill.
Sponsored

 
Last edited:
OP
OP
dml105

dml105

Well-Known Member
Joined
Jul 26, 2020
Threads
23
Messages
906
Reaction score
1,348
Location
Arlington, VA
Vehicles
Shadowfax, the Star White Tricoated Metallic Pony
Country flag
Well the owner's manual does say this:
1624228847655.png
I can’t see that applying to this situation in any way.
To be clear, I’m in drive, I’m pointing downhill, and the car rolls back UP the hill backwards when I lift off the pedal.

in one pedal mode, lifting off the throttle should slow you to a stop, but it appears the computer is confused that it has stopped when pointing down a small grade.
 
Last edited:

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
I am assuming you have "auto hold" on? My guess is that is what got confused.
 

ARK

Well-Known Member
Joined
Aug 21, 2020
Threads
42
Messages
2,732
Reaction score
3,986
Location
Los Angeles
Vehicles
Mustang Mach E
Country flag
My experience with hill assist on other vehicles has been that if the car slows to a stop because of a loss of momentum, it will start to roll backwards, that you actually have to press the brake pedal to get it to engage.

I suppose it’s possible that autohold here works the same way, that unless you actually press the brake pedal, the Mach-E will not know to engage the parking brake and therefore hold on an incline when you come to a stop, that the parking brake, assuming you are stopped, is activated through a touch of the brake pedal?
 


OP
OP
dml105

dml105

Well-Known Member
Joined
Jul 26, 2020
Threads
23
Messages
906
Reaction score
1,348
Location
Arlington, VA
Vehicles
Shadowfax, the Star White Tricoated Metallic Pony
Country flag
I am assuming you have "auto hold" on? My guess is that is what got confused.
That’s the one I do NOT have turned on.

Ford Mustang Mach-E Car rolls backwards uphill in D 047D9024-6B7B-46C7-9B06-8113259E2A07

I’m realizing that earlier I said hill assist. I don’t see that setting, so I think I was just wrong.
 

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
@dml105 maybe change the title to "car rolls backward UPHILL when in D on a downhill slope"; people aren't reading carefully and are assuming the auto hold is off and the car is rolling backward DOWNhill.
 

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
That’s the one I do NOT have turned on.

Ford Mustang Mach-E Car rolls backwards uphill in D 047D9024-6B7B-46C7-9B06-8113259E2A07
wow, then I have no idea why the car would get confused. Is it possible you accidentally bumped the shifter into "R" or hit the park assist and it was trying to back into a space or something?

Otherwise call a good priest for an exorcism...
 

Murse-In-Airy

Well-Known Member
First Name
Rod
Joined
Mar 5, 2021
Threads
74
Messages
3,389
Reaction score
7,618
Location
Chaumont, NY
Vehicles
Mach-E ER AWD
Occupation
Nurse
Country flag
@dml105 maybe change the title to "car rolls backward UPHILL when in D on a downhill slope"; people aren't reading carefully and are assuming the auto hold is off and the car is rolling backward DOWNhill.
This was my assumption too. And I think the warning in the owners manual DOES apply because, while rolling backward up a hill is certainly VERY weird, it pretty clearly says if you don’t want to move, put your foot on the brake. Driver assist features are there to assist, not replace your inputs.
 
OP
OP
dml105

dml105

Well-Known Member
Joined
Jul 26, 2020
Threads
23
Messages
906
Reaction score
1,348
Location
Arlington, VA
Vehicles
Shadowfax, the Star White Tricoated Metallic Pony
Country flag
This was my assumption too. And I think the warning in the owners manual DOES apply because, while rolling backward up a hill is certainly VERY weird, it pretty clearly says if you don’t want to move, put your foot on the brake. Driver assist features are there to assist, not replace your inputs.
In 1PD, lifting the pedal means stop. Not slow down, stop, then go backwards.

kinda defeats the purpose of 1PD if I have to emergency shift to the brake pedal to avoid crushing pedestrians behind me, uphill from me.
 

JamieGeek

Well-Known Member
Joined
Dec 29, 2019
Threads
82
Messages
3,556
Reaction score
6,746
Location
Southeastern Michigan
Website
spareelectrons.wordpress.com
Vehicles
Mach-E, old: Bolt, C-Max Energi, Focus Electric
Country flag
In 1PD, lifting the pedal means stop. Not slow down, stop, then go backwards.

kinda defeats the purpose of 1PD if I have to emergency shift to the brake pedal to avoid crushing pedestrians behind me, uphill from me.
It doesn't necessarily mean stop, also from the owner's manual:
Ford Mustang Mach-E Car rolls backwards uphill in D 1624238657708


Of course this doesn't mean that the car will move backwards once stopped but it does mean that you should beware and use the brake pedal if necessary.

Thus with my two excerpts Ford is saying that 1-P mode does not guarantee that the car will come to a complete stop when you lift your foot off the pedal.
 

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
I think the car is inverting the power to the motor and running it in reverse to hold it static. In this case it's overcompensating.
That's what I was thinking too, but he has auto hold "off". If he releases the brake the car should roll forward downhill
 

mr_raider

Well-Known Member
Joined
Dec 22, 2020
Threads
8
Messages
428
Reaction score
318
Location
Montreal, QC
Vehicles
2021 Mustang Mach-E Select AWD
Country flag
That's what I was thinking too, but he has auto hold "off". If he releases the brake the car should roll forward downhill
No. Two of three drive modes apply some "regen" intrinsically to dampen coasting. This might be a case of that.
 
OP
OP
dml105

dml105

Well-Known Member
Joined
Jul 26, 2020
Threads
23
Messages
906
Reaction score
1,348
Location
Arlington, VA
Vehicles
Shadowfax, the Star White Tricoated Metallic Pony
Country flag
It doesn't necessarily mean stop, also from the owner's manual:
1624238657708.png


Of course this doesn't mean that the car will move backwards once stopped but it does mean that you should beware and use the brake pedal if necessary.

Thus with my two excerpts Ford is saying that 1-P mode does not guarantee that the car will come to a complete stop when you lift your foot off the pedal.
I understand that, but to go UP a hill, the car has to power the motors. The sections of the manual you have cited are referring to 1PD not being able to slow the car all the way to a stop when on a steep grade. That is not what is happening here.

Today, coming out of a parking garage near a baseball stadium, I was waiting to make a left turn onto the main street. The car was in D on 1PD mode, and I was stopped. The car was pointing down a maybe 15% grade on an apron. I inched forward to attempt the left turn, but traffic prevented it, so I lifted off the throttle again. The car stopped, AND THEN ROLLED BACKWARDS, UP the 15% graded apron as if it were in reverse. That requires active power -- gravity would have put me onto the street in front of my current position.

It is very fortunate that the drove of fans coming out of the baseball game saw the car rolling backward and jumped out of the way while I jammed on the brake. I don't want to overdramaticize this though, as the car moved no more than maybe 3 feet, and was at very low speed (< maybe 2 mph.)

So you see, this is not a case where the Mach-e was unable to stop. Instead, this is a case where the car actively powered backwards while in drive.
 
 




Top