[dmcsweeney]

Hi all,

My neighbour recently fitted non run flats to his '14 520d M Sport and has been experiencing regular low pressure warnings despite inflating the tyres to the specified pressure. He has also told me that he is getting traction control warnings on the dash that cause the car to lose power (under gentle acceleration). I haven't seen the car for myself yet, but has anyone experienced anything similar? The issue only began when he fitted the NRFs to the front recently.

Regards,
Dave

[morellomax]

2014 = post-LCI = should be proper RDC pressure sensors in each wheel.

Has he really just put non-RFT tyres on the same rims, or has he got a new set of rims with non-RFT tyres already mounted ?

There is no way for the car to tell whether tyres are RFT or not. The tyres themselves are completely "dumb", no RFID tag or other electronic signature. So either he changed to rims with no, or the wrong, sensors fitted, or one or more sensors got damaged by the fitters or one or more tyres isn't sitting flush on the rim. 3 years is too soon for the battery in a sensor to give up I think.

What does idrive say about the individual tyre pressures ? How does this compare with a manual reading of the pressures ?

[morellomax]

Hang on - he's only fitted non-RFTs to the front ????!!!

[dmcsweeney]

Originally Posted by morellomax

2014 = post-LCI = should be proper RDC pressure sensors in each wheel.

Has he really just put non-RFT tyres on the same rims, or has he got a new set of rims with non-RFT tyres already mounted ?

There is no way for the car to tell whether tyres are RFT or not. The tyres themselves are completely "dumb", no RFID tag or other electronic signature. So either he changed to rims with no, or the wrong, sensors fitted, or one or more sensors got damaged by the fitters or one or more tyres isn't sitting flush on the rim. 3 years is too soon for the battery in a sensor to give up I think.

What does idrive say about the individual tyre pressures ? How does this compare with a manual reading of the pressures ?

The tyres were on the same rims. I didn't know you could view the individual pressues so I'll check them later. Is my Pre LCI the same?

Thanks,
Dave

[dmcsweeney]

Originally Posted by morellomax

Hang on - he's only fitted non-RFTs to the front ????!!!

They are now fitted all round. They were only on the back initially but there was no issue.

Regards,
Dave

[Piers]

So if the rears were ok, then it could potentially be a front sensor issue?

[morellomax]

Or maybe the fronts are the wrong size ? If rolling radius of fronts is different to rears, would that cause warnings based on ABS sensor data ?

[The Beast]

Yeah I was thinking tyre size too

Has he tried varying tyre pressures?

[dmcsweeney]

Gents,

The same thought struck me last night. He was out all evening yesterday so I haven't seen the car yet. I'll check it out later. I'll also check the pressures using my own tyre gauge as it has only been checked on a garage forecourt, and how many times has that been dropped?? I once ended up nearly 10 PSI over inflated when I trusted one of those.
Regards,
Dave

[dmcsweeney]

Hi all, I finally got to see the car for myself this evening. Driving it gently the car kangaroos and a message comes up on the left of the dash about a stability issue and to drive cautiously (or something to that effect) along with the odd flash of the MIL. When I stopped and checked the tyres the aspect ratios are different;
Rear: 275/40 R18
Front: 245/45 R18

I assume this is incorrect? I never checked the nearside to see if they matched. Inflating the tyres apparently cures the problem temorarily. It showed no tyre pressure warnings. The car does not have tyre pressure sensors and was built Jan 2014. I assume the tyre fitted fitted the wrong tyres?

Edit; having worked it out this looks correct. Any other thoughts?

Thanks,
Dave

[dmcsweeney]

The problem has now developed further. I've just had a call to say the car cut out while shifting from reverse to drive and is refusing to start!
Regards,
Dave

[xenon]

Tyre sizes definitely correct - aspect ratios are different because the widths are different.

[dmcsweeney]

Originally Posted by xenon

Tyre sizes definitely correct - aspect ratios are different because the widths are different.

Thanks! Think we can definitely exclude the tyres now! I'm going to take a look at it later. I have encountered multiple strange warnings and codes in the past on Jags when the battery wasn't 100%. I'm starting to wonder if this could be the issue. I can't see how a traction system warning could lead to a non starting issue. I've spoken to a very knowledgeable indy and he has never seen it before. Given the fact that it hasn't rained in over a week I don't think it's a water ingress issue.
Regards,
Dave

[dmcsweeney]

Hi all,
Yet another update. I took another look this evening and the engine fired up first go.I drove it a few feet and it stalled. It re started up stalled again shortly after. I fired it up and checked the voltage at the jump start point, all good. The engine revs rose twice and dropped as I watched it idle. I then shut it down, re started, and switched off the traction control. On the first test drive I thought it drop back a little once. Next drive (4 miles) all seemed fine with no warnings. I could find my code reader (though I doubt it would tell me much). The JLR software (mongoose) is widely available but I'm new to BMW, is the software or a decent diagnostics tool available?
Thanks,
Dave

[xenon]

Sounds like an ABS Sensor.

[dmcsweeney]

Originally Posted by xenon

Sounds like an ABS Sensor.

I assume it will take dealer software to figure out which one is at fault?

Thanks,
Dave

[xenon]

It will but the software is available on line. Can't be far outside warranty though so a dealer might do a goodwill.

[dmcsweeney]

Originally Posted by xenon

It will but the software is available on line. Can't be far outside warranty though so a dealer might do a goodwill.

Thanks again mate. I'll have a look online in a moment for the software as I'll probably need it in the long run. I had a quick look and a C110 code reader came up. Are they any use or should I just go for the software? If so has anyone bought it lately?

Thanks,
Dave

[Fox530]

Originally Posted by morellomax

2014 = post-LCI = should be proper RDC pressure sensors in each wheel.

Not neccesarily - only cars built after March 14 have the individual sensors in each wheel as standard, so there could be a few 14 plates kicking about without them.

[dmcsweeney]

Originally Posted by Fox530

Not neccesarily - only cars built after March 14 have the individual sensors in each wheel as standard, so there could be a few 14 plates kicking about without them.

That seems to be correct as this car doesn't have them (LCI built Jan 14)

Thanks,
Dave