Sudden acceleration

[Ian Key]

Reading paragraph No. 2 I'm just wondering if the ACC was accidentality activated, for example the star button was pressed and the driver caught the pilot switch, causing the car to accelerate to 20mph. But why didn't it activate the brakes when it detected the van in front?

 

[tsedge]

Hmmm... this is concerning!

When people talk about ACC not working (not Ian) are you referring to AEB? Automatic Emergency Braking? That would make more sense.

I would note:

- Pressing the wrong pedal and not realising it IS a real thing. People are certain they used the brake when they did not. Their muscle memory plays a trick on them.

- It is certainly possible a bug could exist in the car somewhere but this is obviously something there are rigorous safeguards against.

Since there can be no evidence on what really happened, short of having a footwell camera in sync with an outside camera, I am not sure what to make of these reports.

 

[Edd Beesley]

They almost always occur in car parks/when manoeuvring. With the interaction between creep/hill hold/regen/opd and changes of direction there’s a lot going on (for the driver). Gently holding the brake just the right amount to control your creep to move forward to slowly park feels very similar to gently holding the accelerator just the right amount to move forward to slowly park if there’s a hill or gravel or mud involved, for example.

I have made the reverse mistake (many years ago in a Prius), thinking I was gently holding the accelerator going through a roundabout, then wanted to speed up. I pushed the pedal and slowed down, pushed harder and hit a dead stop. If I can make that mistake then it’s very easy to believe people make the reverse mistake. Only takes a minor distraction, something on the radio, seeing something odd out the window, thinking about another car while operating this one, being in a different emotional state, or simply being in a rush.

 

[DaevM]

Not very helpful I know, but feel it needs to be said about now - "bloody computers!! " .
( apologies to those offended )

View attachment 25586

Reading paragraph No. 2 I'm just wondering if the ACC was accidentality activated, for example the star button was pressed and the driver caught the pilot switch, causing the car to accelerate to 20mph. But why didn't it activate the brakes when it detected the van in front?

I'm trying not to use any of the assists that I have control over.
I used to use ( and loved) cruise control in all my previous vehicles including my last ev, Kia Soul. It was possible to leave CC on but not active, i.e. overriden by braking / accelerating ( but mostly braking) . Is it the same with the MG4 ? - Switched on but not active ACC ?
If so, presumably the potential for some 'confusion', whether on behalf of the user or the vehicle is a possibility.

 

[fnegroni]

They almost always occur in car parks/when manoeuvring. With the interaction between creep/hill hold/regen/opd and changes of direction there’s a lot going on (for the driver). Gently holding the brake just the right amount to control your creep to move forward to slowly park feels very similar to gently holding the accelerator just the right amount to move forward to slowly park if there’s a hill or gravel or mud involved, for example.

I have made the reverse mistake (many years ago in a Prius), thinking I was gently holding the accelerator going through a roundabout, then wanted to speed up. I pushed the pedal and slowed down, pushed harder and hit a dead stop. If I can make that mistake then it’s very easy to believe people make the reverse mistake. Only takes a minor distraction, something on the radio, seeing something odd out the window, thinking about another car while operating this one, being in a different emotional state, or simply being in a rush.

True. But a few months back, I was basically boxed into my parking space and had to perform close to 50 forward and reverse manoeuvres to get the car out, including having to get out the car regularly to check how many inches spare I had with the walls in front and behind, the pillar to my left and the abysmally parked car next to me.
If there had been a bug that would have triggered it I think.
The only times I catch myself going the wrong direction while doing a three point turn is when I forget that reverse is twist counterclockwise.

 

[siteguru]

Not very helpful I know, but feel it needs to be said about now - "bloody computers!! " .
( apologies to those offended )


I'm trying not to use any of the assists that I have control over.
I used to use ( and loved) cruise control in all my previous vehicles including my last ev, Kia Soul. It was possible to leave CC on but not active, i.e. overriden by braking / accelerating ( but mostly braking) . Is it the same with the MG4 ? - Switched on but not active ACC ?
If so, presumably the potential for some 'confusion', whether on behalf of the user or the vehicle is a possibility.

Yes it is ... if a speed target is set it appears near the top-left of the driver display. If it is Grey then ACC is off; White then ACC is available but not active; Green then ACC is active.

TJA works the same, the difference being that you also see a steering wheel icon in that area (following the same colour scheme).

 

[Tig170]

Only once in the MG4, but was all down to the car mat (which became dislodged, and got stuck over the throttle peddle), now know the characteristics

 

[Kathy]

Has anyone experienced the car accelerating fast without warning?
I’ve just tried to park, took my foot off the accelerator and the car shot forward. Just checked and it has hit the parking bollard, denting the front bumper a little.
Did the ACC kick in?
Felt it did this earlier too.
Another scary experience. I’m shaking.

I had the same thing in January, I was pulling into a parking space and the car launched forward into a post, now I have been waiting more than 4 months for parts

 

[trazak]

I'm not saying there wasn't a fault with the car but when this happens with automatics it's often because the driver's foot is on both pedals at once and the more they brake the more the accelerator gets pressed down.

How does one foot be on both the accelerator and brake at the same time ???

 

[Ian Key]

How does one foot be on both the accelerator and brake at the same time ???

Easy if you have big feet with wide shoes.
Don't ask how I know

 

[m4rmite]

Works boots.
Caught both pedals many times, not enough to shoot off but enough to make you think ooh err madam.

 

[Kithmo]

Works boots.
Caught both pedals many times, not enough to shoot off but enough to make you think ooh err madam.

I actually have a different problem with my size 11s.
Because the accelerator pedal is lower than the brake pedal, I sometimes catch my foot on the side of the brake pedal as I'm going to brake causing me to brake a fraction of a second later as I have to jiggle my foot up and over the brake pedal, another ooh err moment.

 

[JeanLeFlambeur]

Does slamming on the break pedal (assuming not mat in the way) not overcome any unintended acceleration by the car?

 

[Tight Git]

Yes - it will/should, however there are many instances where they are actually pressing the accelerator pedal thinking it is the brake pedal.

 

[Kithmo]

Does slamming on the break pedal (assuming not mat in the way) not overcome any unintended acceleration by the car?

The motor is stronger than the brakes, so if it is a fault with the accelerator then no.

 

[mg4mc]

Have you tried pressing the accelerator and brake together? In my MG4 I can floor the accelerator whilst gently pressing the brake, as soon as you touch the brake all power to the motor is cut.

 

[Kithmo]

Have you tried pressing the accelerator and brake together? In my MG4 I can floor the accelerator whilst gently pressing the brake, as soon as you touch the brake all power to the motor is cut.

Not on mine, look at the power distribution on the battery page.
At first there is no power to the rear wheels, but when you floor it it flows.
Admittedly the car doesn't move so it's obviously not strong.

 

[mozza]

This same thing happens to me, any bump whilst braking will cause the car to fly forward. Sick of reading all this bollocks about driver error. Car is just faulty, I still drive it, I'm used to it and expect it to happen.

Different car, but I've noticed one thing with my MG5, under KERS 3 braking, if one of the drive wheels goes over a manhole cover it can cause the car to launch forward with rapid acceleration, so I try to avoid manhole covers while slowing down.

 

[Rolfe]

Mozza, as @emmrecs suggested, you really ought to take this to the MG5 forum, where there will hopefully be people better able to help you with your car.

 

[fnegroni]

This same thing happens to me, any bump whilst braking will cause the car to fly forward. Sick of reading all this bollocks about driver error. Car is just faulty, I still drive it, I'm used to it and expect it to happen.

Interesting. I had something similar on the MG4 and stock tyres: they would lose grip suddenly and it was earful especially on some rubber speed humps near home.
I changed tyres. Problem solved.