F46 218d traction momentary power loss

[itiejim]

2015 F46 218d Gran Tourer - occasionally there is a sudden and very brief interruption to power delivery, almost as if the traction control is cutting the power momentarily. This can occur even at steady speed on a light throttle.

I don't have any CELs or apparent signs of other issues. The car otherwise drives well, pulls as strongly as can be expected and is happy enough under load.

Possible sensor or reluctor ring issue?

[nsa]

Do you have any pedestrian collision avoidance systems? A friend's Qashqai does this but it applies the brakes at the same time.

[itiejim]

Sadly yes, but when that intervenes the car makes a specific chime and a large light illuminates in the dash.

This is a very brief interruption to power.

[E-bmw]

Is it possible that you have 1 tyre significantly more worn than the others or a ditch finder on 1 corner & this is skewing things?

[itiejim]

All the same Michelin Cross Climate + tyres, albeit I have just fitted two new ones on the front. The rears still have about 3 mm tread.

The problem does seem to have started since fitting the tyres though.

[E-bmw]

Check the pressures are perfect & the new ones are on the same axle.

Did you go down a size for the tyres and use them as winters, or do you use the standard size and them all year round?

Check all 4 have been fitted with the same exact size/load/speed rating etc.

[itiejim]

Thanks for the reply, the tyres are the same size as factory and all have the same size, speed rating and load index.

I have checked the pressures this morning and performed a reset of the tyre pressures via the I-drive, which I thought had cured it, but sadly just had another momentary power interruption now, during a 35 mile journey.

It really is just as though the power was turned off for less than a second. The economy gauge drops down, as though you had released the throttle, and then a moment later it goes back to normal. This was during light throttle application travelling at around 50 mph.

It's a little thing, but it's my wife's car and I don't want it to let her down. I have used INPA on my old E46, so I think I'll order another cable suitable for this and see if there are any error codes.

Any thoughts on my suggestion of reluctor rings or ABS sensor?

[E-bmw]

You could check the rings are clean but if it were either ring or sensor you would have codes hence why I was leaning towards tyres.

Have you had a geometry check done recently?

[itiejim]

No, but the tyres which came off the front had done 30k miles and worn evenly and there are no other indications that it needs doing.

I haven't checked the codes, so I think I I'll order a K+Dcan cable and see what INPA picks up.

[itiejim]

Ok, had a look at the codes and it seems it is the EGR valve.

Can these be successfully cleaned out or, at 60k miles, should I just put a new one in?