4.8is Air Suspension - dropping on nose - SOLVED

[LVR]

Hi

As there are a lot of threads about 4 corner suspensions dropping on the front or rear, I thought I'd detail how the 3 simultaneous faults on mine have been found and fixed in the hope it helps someone else.

Others have pointed out the main issues are leaks, but in this case there were no leaks so it had to be electrical

Symptom - collapsed on front, height switch inactive

The first attempt at getting to the bottom of it was obviously checking for leaks in the front bags and system lines. There were no leaks so my indy reinitialized the system. The front returned to normal height and all was well, although the switch would not respond.

Several weeks later I drove the car over an off camber steep corner. It was uphill and meant that I almost had a wheel in the air it was that steep. The front immediately collapsed when I stopped.

Symptom - collapsed at front, height switch inactive, Tyre pressure monitor light amber

I got under the front to have a look and noticed that the ride height sensors looked different from one side to the other.

One looked correct with arm pointing upwards per the BMW diagrams



The other looked weird...



I undid the sensor and reset the arm correctly but it didn't make any difference.

Returned to my indy and he tested the sensor to find that the sensor (although operating), wasn't outputting the correct signals. Had we found the issue? He replaced the sensor and reinitialized the system. Fault 1 repaired, all good and returned to correct height..... but switch still not operating.

Several days later I parked on an uneven driveway. Started the car and drove off and happened to notice that the compressor came on (briefly) and stopped. I didn't think anymore about it until I got home and saw the weird angle on the car.

Symptom - uneven ride height front to rear, RED tyre pressure monitor light and 4x4 amber light.

I was beginning to suspect the battery was becoming an issue, as the compressor had cut out before leveling the car when I was driving. I tested the battery voltage and found that it was down to just over 12 volts when in standby state ie no load (I had tried to charge it but the charger wouldn't play).

So, a new battery went in and Fault 2 is sorted.... but still no change although we have amber tyre pressure light.

By now while waiting for time to install the new battery, the front has collapsed again completely and I'm starting to look at the reality/cost of Bilsteins all round....

I rang my indy and started discussing what was going to be involved based on what I had researched. In fairness, there doesn't appear to be much around other than a few people doing coilovers for a harder ride.... not sure as to what to do as the ride's hard enough I think....

I also suspected the compressor might be getting worn out as my indy had remarked on the first visit that it had taken a long time to pump up when reinitialized. I decided I would install a compressor refurbish kit just to be safe. It was only $20 ish AUD and the supplier had a tutorial so I figured why not.





I bought this direct from a supplier in the UK called X8R and pulled the compressor out.



Followed their step by step instruction on how to install the new compressor O ring and piston seal so in it went in about an hour...





Fault 3 repaired but still sitting on its nose and warning lights... and switch not working STILL!

Hmmmm ...

I decided to visit my indy again and see if the new battery and compressor would benefit from another re initializing...

Voila!!! Sure enough, switch now works, car goes up and down quite quickly (which its never done), indy noted it has a lot more oomph in the compressor, switch lights activated, ride heights all spot on.... maybe we can forget the Bilsteins...

Happy days...

So, to recap it appears that the sensor was the initial culprit, but then compressor and low battery were too weak to get it back up.

I know it can be a frustrating system, but here are 3 things for anyone in future to check.

Cheers