4.8is Air Suspension - dropping on nose - SOLVED
 

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 :doh:

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

https://xoutpost.com/members/lvr-alb...3-14-07-50.jpg

The other looked weird...

https://xoutpost.com/members/lvr-alb...3-14-08-29.jpg

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.

https://www.x8r.co.uk/webimages/wabco2.png

https://www.x8r.co.uk/webimages/wabco3.png

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

https://xoutpost.com/members/lvr-alb...9-img-4891.jpg

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...

https://xoutpost.com/members/lvr-alb...0-img-4898.jpg

https://xoutpost.com/members/lvr-alb...1-img-4902.jpg

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

Hmmmm ... :banghead:

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

Thank you for taking the time to post this! Very useful.

+1 Thanks

I say this again. INPA is a must for these cars. I must have “fixed” my system 5 times over the years with a basic error reset on the air ride. I also excerside the living piss out of mine. Every time I start driving I raise car to the top, let the system air down on its own after some speed. Sometimes drop it all the way down. But I usually just raise max or leave in center. Figured keeps the parts moving and tensions up the suspension, I do raise it in the winter and other instanses, so don’t want the system to freak out. So far so good.

These systems are just funny. They need a reset because silly shit seems to set them off. Any error, I check what’s going on. You need to be able check if compressor overheating, voltage, sensor faults. If you address issues right away you can keep this air suspension running no problem. But you need INPA available.

Chill mate. This thread was about the reasons BEHIND the problems.

Thank you! My problem was electrical as well. Turned out my compressor and a fuse was kaput.

I have never needed INPA suite for anything. It sits on a laptop in a drawer and has for years.

You don’t have 2 axle air either. Just saying.

My bad LVR. Didn’t mean to come off hard. Just my recommendation for these cars.

I have found this post very interesting. The suspension on the 4.8is is currently completely down and I have an SLS error message on the dash. I have replaced both front airbags having detected leaks, the front left sensor and the battery. My scanner (Foxwell 510) currently tells me there is a fault in the accumulator pressure sensor but I don’t trust it (have INPA on order). Is there a way of confirming a fault in the sensor? It has three wires into it blue, yellow, green. Also when configuring your suspension do you need to make sure that both “Transport” and “Line” are “not set”?

I also put one of those kits in the compressor when my indie said it was down a bit on pressure.