MG4 Restricted speed - weird

[bowfer]

Hard to digest that it took them weeks to come up with this idea. Is it faulty or not? Can't it be diagnosed?

Edit: Do you have access to a spare car? I mean when you reject it, you might end up with no car.

No idea to the first part.
Yes to the second part.

 

[Cocijo]

My preferred option?
Money back and I never visit an MG dealer again.
But if that’s going to be a protracted legal wrangle, a whole new car (pre done with oil overflow etc) will be grudgingly accepted.
Woe betide them if that develops any faults though (which it will, let’s be honest here)

So you’ve decided that your‘re rejecting it?

 

[Macadoodle]

MG still stumped but have suggested a new traction motor is fitted and see how that works.

Arrr, I thinks they be loading the parts cannon, you could be in for a wait if you stick with it, Arrr.

Of all the components the motor would be my last guess, if I had to guess.
Its just some field coils when all's said and done.
A coil usually has continuity or it doesn't, earth leakage is pretty simple to test for.
Maybe they suspect the inverter but I would have thought that's a separate component despite living atop the motor and sharing the same coolant loop.

Hard to believe they don't have a fault code flagged up somewhere with the system restricting its designed power output. Bizarre.

 

[bowfer]

So you’ve decided that your‘re rejecting it?

I can’t see any scenario where I’ll take that specific car back.
That will be fought tooth and nail.

 

[Deleted member 10041]

If it was me I'd reject it, the only other option that makes sense for me is a brand new car on the same terms, I'd also want evidence of the breather and a decent test drive to check things out and they are working as they should

I don't think I'd have any faith in your current car, no matter what was replaced

 

[Mars6394]

My preferred option?
Money back and I never visit an MG dealer again.
But if that’s going to be a protracted legal wrangle, a whole new car (pre done with oil overflow etc) will be grudgingly accepted.
Woe betide them if that develops any faults though (which it will, let’s be honest here)

I was in the same boat as you they had my car 9 weeks in total from 12 I owned it.I went for rejection it got refused as they offered to fix but if anything fails afterwards same issues it can be rejected.I hope u get sorted I had to have a new BMS system fitted to mine been ok since hopefully

 

[Eber]

I was in the same boat as you they had my car 9 weeks in total from 12 I owned it.I went for rejection it got refused as they offered to fix but if anything fails afterwards same issues it can be rejected.I hope u get sorted I had to have a new BMS system fitted to mine been ok since hopefully

Was the long wait due to difficult diagnosis or parts availability?

 

[Mars6394]

Was the long wait due to difficult diagnosis or parts availability?

it was staff availability as there was only 1 technician trained in this area of the problem I had.so I was told

 

[Cocijo]

I was in the same boat as you they had my car 9 weeks in total from 12 I owned it.I went for rejection it got refused as they offered to fix but if anything fails afterwards same issues it can be rejected.I hope u get sorted I had to have a new BMS system fitted to mine been ok since hopefully

I must admit, I thought bms would be looked at and I’m surprised the motor is being replaced In this case.

 

[tsedge]

I must admit, I thought bms would be looked at and I’m surprised the motor is being replaced In this case.

I agree, motor would be the last component I would suspect. New battery/BMS much more likely.

 

[Miscreant]

Looking at one of those Bjorn test videos on the MG4 on YouTube and he seemed to come across a power limitation in the LFP powered version he has. At one point, he couldn't get more than 70% or thereabouts from the motor so there may be some sort of software issue here. Doesn't help the OP in this case but I remembered this thread when I watched the video.

 

[siteguru]

I recall from Bjorn's recent video that he was down to about 6% SoC and floored it, and got 86% power.

 

[Miscreant]

The one I watched, he was doing a hill climb and the SOC was well above half when he reached a power limit.

 

[bowfer]

update
The dealer has advised the motor will be fitted at MG’s leisure, I’m ‘allegedly’ getting a new car.
When…..when….I hear you ask…
I don’t knoooow is the cry as I disappear into the distance in my grandad taxi 5….

 

[tsedge]

update
The dealer has advised the motor will be fitted at MG’s leisure, I’m ‘allegedly’ getting a new car.
When…..when….I hear you ask…
I don’t knoooow is the cry as I disappear into the distance in my grandad taxi 5….

Good that you are getting a replacement.

Driving granddad's taxi will be good practice for later life.

 

[Ian Key]

update
The dealer has advised the motor will be fitted at MG’s leisure, I’m ‘allegedly’ getting a new car.
When…..when….I hear you ask…
I don’t knoooow is the cry as I disappear into the distance in my grandad taxi 5….

Get all those tip runs done while you have the larger boot

 

[tsedge]

The one I watched, he was doing a hill climb and the SOC was well above half when he reached a power limit.

I can certainly understand power restrictions when taxing the car repeatedly (eg hill climb, circuit driving), quite a few EVs will overheat and limit power in these scenarios.

Power limitations on low charge are also not uncommon.

But that's quite different from @bowfer who had speed limits at all states of charge and even on short journeys.

I think it must be a software bug - perhaps a BMS issue - and undiagnosable with the equipment MG dealers have. I would expect an update in the future to fix this.

Just possibly the motor has protective sensors and logic and this is either buggy or misreading the motor's state, but if that were the case it should throw a clear diagnostic code. Baffling.

 

[bowfer]

Get all those tip runs done while you have the larger boot

You know, that’s a weird thing about the 5.
It looks ‘estate’ but then you open the hatch and it’s not flat.
There’s a lip for you to lift stuff over.
oh and the seats don’t go flat.
It’s really just an elongated hatchback.

 

[bowfer]

Update
MG insisting they get the opportunity to replace the traction motor before rejection.
Happy enough to let them do this, as I’m not even remotely convinced it will fix the issue.
So I’ll let them hang themselves with their own rope.
As of Thursday it was allegedly getting done this week.

 

[Macadoodle]

Update
MG insisting they get the opportunity to replace the traction motor before rejection.
Happy enough to let them do this, as I’m not even remotely convinced it will fix the issue.
So I’ll let them hang themselves with their own rope.
As of Thursday it was allegedly getting done this week.

If its a motor / inverter assembly, maybe. Motor alone, I'd be very surprised if there's any change. Just doesn't add up in relation to the fault you have described IMO.
Straws and grasping methinks.