2008 Z4 3.0si run flat tyre pressure monitoring won't initiate

[Cliff Robinson]

I've got a problem: Last week while driving I heard an usual noise from the nearside rear wheel. Investigation showed the run flat tyre was damaged and completely deflated and the wheel rim split and past repair. I never got any indication of low tyre pressure from the Run Flat Indicator, (RFI), system, and this has worked perfectly in the past. Following replacement of tyre and wheel, the garage checked the ABS system and said they could detect no faults with the braking system which initiates the RPI.

Since taking the car back home I have subsequently checked the RFI system by initialising it, taking it for a run and then dropping a rear tyre pressure by 1bar and driving it again. The RFI gave no indication of a low tyre pressure.

I pumped up the tyre again, and repeated the test, this time dropping a front tyre pressure by 1bar; again the RFI gave no indication of low tyre pressure.

Has anyone experienced this problem or know what the cause is? The local BMW garage have not come across it before and have been unable to help. I'm not keen on driving any distance at speed without the RFI system working, as I could have a tyre deflation at high speed and know nothing about it.

Any help or advice would be much appreciated

Cliff Robinson

 

[t-tony]

I've got a problem: Last week while driving I heard an usual noise from the nearside rear wheel. Investigation showed the run flat tyre was damaged and completely deflated and the wheel rim split and past repair. I never got any indication of low tyre pressure from the Run Flat Indicator, (RFI), system, and this has worked perfectly in the past. Following replacement of tyre and wheel, the garage checked the ABS system and said they could detect no faults with the braking system which initiates the RPI.

Since taking the car back home I have subsequently checked the RFI system by initialising it, taking it for a run and then dropping a rear tyre pressure by 1bar and driving it again. The RFI gave no indication of a low tyre pressure.

I pumped up the tyre again, and repeated the test, this time dropping a front tyre pressure by 1bar; again the RFI gave no indication of low tyre pressure.

Has anyone experienced this problem or know what the cause is? The local BMW garage have not come across it before and have been unable to help. I'm not keen on driving any distance at speed without the RFI system working, as I could have a tyre deflation at high speed and know nothing about it.

Any help or advice would be much appreciated

Cliff Robinson

Does it not show any fault codes?

Tony.

 

[Cliff Robinson]

No fault codes on the dash whatsoever, and the Run Flat Indicator appears to initialise correctly

Cliff

 

[t-tony]

No fault codes on the dash whatsoever, and the Run Flat Indicator appears to initialise correctly

Cliff

I meant have you had a code reader plugged into the diagnostic socket to check for fault codes. It's not certain the BMW Dealer will have.

Where are you located please Cliff?

Tony.

 

[Cliff Robinson]

Hi, the garage who provided the new wheel and tyre also serviced the car. There were some fault codes standing but they all cleared. The only one associated with the ABS was ABS/LWS steering angle sensor: Trouble code 9: CAN BUS Function faulty, but as I said all the fault codes cleared.

I have been advised by a local BMW specialist to check the tyre pressures, re-initialise the system and run the car for 300miles with frequent tyre pressure checks; apparently the system can can a while to settle down . Then after 300 miles drop 1 tyre pressure by 1bar and see if the RFI initiates.

I'm going to try that and see what happens, at least its a plan. The only other alternatives is to take to the BMW garage, but they will want to start changing bits which could get expensive.

Cheers, Cliff

 

[t-tony]

I had a 2003 E85 and the pressure drop did seem to be more effective after I fitted non runflat tyres. I think I would try dropping the pressure a little more than 1 bar if you're still on runflats. My E89 is still on runflats but as soon as they're done I certainly won't replace them with more of the same.

Tony.

ps. Have you checked to make sure one of the old codes has returned? If you don't have a code reader there may be a member near to you who has and would check for you. Me included if you're anywhere near me.

 

[Cliff Robinson]

Hi, I'll ask the garage to recheck for fault codes, but otherwise I'm going to stick to this 300 mile run and then retest. I will however drop the pressure down to 1bar when I test it, but I'm not going below that. The RFI system has always worked reliably in the past, sometimes too reliably, and I've always run with run flat tyres on it. I've had good experience and performance with the run flats, although coupled with the hard suspension they do make for a bone jarring ride on our rough roads. I'll let you know how I get on.
Cliff
Ps. I'm located in the North West a few miles north of Lancaster

 

[t-tony]

Hope you get to the bottom of it Cliff. Please keep us posted.

Tony.