OPD, car rolls backwards when stopping on downhill slopes (merged thread)

[Rockstar]

Hello,
I am making a quick call to get your feedback on my use case.



Every morning, I leave home (1) and activate the one-pedal (UC with OP only). On the downhill road (not depending charge level), my MG4 regenerates strongly in this phase with peaks to -25.
The deceleration is not sufficient to stop before the panel, on the false flat going down I apply a little brake. (2)

I hear rubbing noises from the brakes, my car stops, I release the brake and then the vehicle reverses. (between 50cm and 2m depending on the case, every time, I reproduce the problem on this road).

Using the OP continuously since September and taking this street almost every day, I became aware of this phenomenon following an module update in January.

The MG dealer noticed the problem and told me that he reproduced it with a vehicle without the shift, and that it is really linked to the profile of the road. He has no solution and makes me understand that it is incidental.

Can anyone tell me which modules support OP and regeneration? And share any feedback about this issue?
Thanks

 

[Burgo]

What a coincidence! Two days ago I think a similar thing happened to me. Using OPD, after 'coasting' down hill I pulled off the main road onto a less steep slip road, before braking to a halt on the leveI. I swear the car started reversing back immediately after stopping making me hit the brake. It's never happened before and maybe was the first time I've gone that way using OPD. I'll try that route again and see what happens!

 

[Rockstar]

Could you share versions , car's model and patching dates?
have you informed MG offical dealer to open a ticket to MG?

Feel free to share test results and some news.

 

[NLMGSAN]

Wow! This is one hell of of bug ....

 

[Burgo]

Could you share versions , car's model and patching dates?
have you informed MG offical dealer to open a ticket to MG?

Feel free to share test results and some news.

Ours is a Luxury, which is equivalent to the UK Trophy but with heat pump and 11kw on board charger. The Infotainment version is R46. We have no issues with any of the driving aids - LKA, Auto dipping lights, Braking, etc, etc are all perfect.

Haven't informed the dealer as, to be honest, it was so bizarre I didn't really believe it. It was the kind of feeling that you get if you go up a steep hill, go into neutral and allow the car to stop and then start to "fall back". As I mentioned, I'll go back and rerun that route and see if it happens again.

 

[Burgo]

Juries out

I've tried a few scenarios in an attempt to force a repeat and am unsure. Under normal driving conditions I can't get it to repeat..
.. But, on one occasion I got a small push back. This was after feathering the accelerator down to nearly a halt (as one would normally when using OPD) but then at the last minute applying the brake fairly hard (harder than normal for the situation) - but only "dabbing" it rather than holding it down.

I put this down to the OPD routine applying a reversing force in order to brake the car, but then at the last minute not reacting quick enough to shut down when the friction brake cut in,thus causing a small "reverse" as the friction brake was swiftly applied, then removed. I asume if the brake is held then this would override the reversing force and so it doesn't happen.

Regardless, under normal conditions this doesn't seem to happen for me (it was only a one off the other day) but it may be worth trying to "force" it to happen under safe conditions to learn more.

That said, it could have been transient vertigo /an optical illusion / hysteria / whatever, but it's intrigued me and I intend to keep an enhanced watch on it for a while.

 

[Rockstar]

In my case, I reproduce every time this bug. It's the resulting of OPD and road profile.
The unique difference between 2 tries is the distance of fall back (40cm to 2m).
An important point, it's to use brake with small pulses and to release it when you feel some friction.
Distance of fall back seems depending of initial speed and regeneration level (stronger -> longer is the distance)
Thanks for testing.

 

[Burgo]

I just got it to happen, with a witness!

On OPD mode with around 68% of battery, after "coasting" down approx 250m of hill with regen I dabbed the footbrske to stop at the junction. When I took my foot off the brake the car powered backwards for around 1 metre.

I suspect that if the footbrake was kept on until the auto brake engaged it wouldn't happen, but by dabbing it it certainly did happen.

Could a few more people try this - though use caution and make sure there is no one behind you? For me it seems to be triggered by a quick "brake / release" to stop after gliding downhill with +ve regén in OPD mode. I suspect the release of the brake is key to this - arguably outside normal operational parameters but intriguing and potentially a issue.

FWIW, there are a couple of reports of the same thing happening in the Australian MG4 FB page:
"I think this must be an issue with OPD. After my car was updated to R11 i noticed that the car would reverse a short distance after coming to a stop also using the brake pedal. I didn't think it was a critical issue because it wasn't reversing far, but i have given up on OPD since then. Your experience sounds very dangerous."

" I had this happen this morning - Essence 64, OPD, did a hard stop (abs engaged) to avoid a roo. When I took my foot off it drove backwards. As soon as I stepped on the brake again it was fine…."

See ffi.

 

[NLMGSAN]

FWIW, there are a couple of reports of the same thing happening in the Australian MG4 FB page:
"I think this must be an issue with OPD. After my car was updated to R11 i noticed that the car would reverse a short distance after coming to a stop also using the brake pedal. I didn't think it was a critical issue because it wasn't reversing far, but i have given up on OPD since then. Your experience sounds very dangerous."

" I had this happen this morning - Essence 64, OPD, did a hard stop (abs engaged) to avoid a roo. When I took my foot off it drove backwards. As soon as I stepped on the brake again it was fine…."

See ffi.

Great news...

 

[Rockstar]

Yesterday, I had some feedback from MG.
My car dealer has specified only "few centimeters" fallback in the ticket. I think that 40cm and more is not "few centimeters". I will ask for adding more informtions in this ticket
The official position of MG is: "It's a normal behaviour. Every MG4 generates a fallback using OPD in this situation. The car is conform!"

Please, @Burgo could you inform your car dealer to open a ticket?

 

[NLMGSAN]

Yesterday, I had some feedback from MG.
My car dealer has specified only "few centimeters" fallback in the ticket. I think that 40cm and more is not "few centimeters". I will ask for adding more informtions in this ticket
The official position of MG is: "It's a normal behaviour. Every MG4 generates a fallback using OPD in this situation. The car is conform!"

Please, @Burgo could inform your car dealer to open a ticket?

If that is so, MG should warn all users, and add it to the manual.

 

[Rockstar]

@NLMGSAN I think it's a good way for MG and car dealer to do nothing.
If because of this bug, you knock somebody down, who should be blamed?

I remember of one case in the past, a renault laguna's cruise control was crazy and blocked the speed without allowing it to be disabled. The car destroyed a highway gate.
Renault position has shifted the blame to the driver but after trial, the driver was discharged.

 

[NLMGSAN]

@NLMGSAN I think it's a good way for MG and car dealer to do nothing.
If because of this bug, you knock somebody down, who should be blamed?

I remember of one case in the past, a renault laguna's cruise control was crazy and blocked the speed without allowing it to be disabled. The car destroyed a highway gate.
Renault position has shifted the blame to the driver but after trial, the driver was discharged.

I do not care about blame. If MG knows it may cause an adverse event, they must inform you as a customer. Then you have two options: ignore MG4s or ignore OPD.

Example: you are about to buy a brand new tv with a smart remote. In some occasions, however, when selecting channel one on the remote the manufacturers knows it will switch to a Russian propaganda broadcast.
Would you prefer to know this before buying? Or only after buying?

 

[Burgo]

It's still rather strange, though, that out of the thousands (?) of MG4s sold there's only 5 or 6 reports of this; it can't be a widespread concern and, as I mentioned earlier, the actions required to induce it are, arguably, extraordinary.

I'd still very much like to see if as anyone else can get their cars to do this...

 

[Rockstar]

@NLMGSAN
Brand would never inform customers about bugs before problems. Sometimes, it doesn't know them or it doesn't want to spend time on that and probably losing future customers.
When the issue is not under control (accident trial,...), brands react to protect themselves.
The issue is not to find bugs or to communicate on that but it's to ignore them and to not assume their responsibility (see stellantis motor, pharmaceutical scandals ...

In general, customers association or customers community are the first to alert people.

This afternoon, I sent a email to MG to inform us directly.

@Burgo
My car dealer has taken randomly one MG4 with OPD and jackpot...
Perhaps, it's a mix between road profile, opd use, sofware version and hardware version but they have to investigate to know.

If you aggregate those conditions, the probabilty to see a public report is very very low. Moreover, people are only communicating with their own community.

 

[Rockstar]

For second times, MG considers this behavior (>1m fall back) as “conform”, known and a 'feature' of MG4 …

 

[MSvirus]

Clearly we need some good multi-angle video of this happening uploaded to youtube where it is named MG4 rear killing mode or something like that. Then attention will occur.

 

[Flightengineer]

When i driving in OPM and stop on traffic light, i see sign of parking brake illuminated green. It has some delay (second) before engaiging which can explane small movement. And after that car stand still no matter uphill or downhill. When you switch on parking brake when parking it's illuminated red. May be your autohold feature disengaged?

 

[Rockstar]

I think that I will publish a video to youtube @MSvirus.

@Flightengineer , Autohold is enabled and moreover, my use ase is out of autohold scope because I was driving and only pushing brake pedal only to slow down.

 

[Rockstar]

I share with you a video of this issue:
It's very dangerous for people who are crossing behind the car.