4.8iS Air Suspension - PROBLEM SOLVED

[4.8iS]

As per thread title...

Mrs 4.8iS was taking the kids to school when the dreaded warning popped up on the dash. She noticed that the ride became very harsh too. Got home and yes, the suspension is obviously not working properly. It is not down, but instead the rear left is fully pumped up, beyond off-road mode. The rest are maintaining some sort of almost normal level.

Plugged in my INPA which comes back with Implausibility Error - speicher ventil and kompressor are pointed as the culprits. The fault resets, but the rear left refuses to go down and then as soon as I drive the car for more than 2 mins, speeds in excess of 25mph, it comes back up.

Anyone had this problem before? Could this be the valve body at the end of the air-tank near the middle of the car or the LHS metal sphere on top of the rear suspension?

Lastly, can anyone recommend a specialist near BR7? ETA are fully booked for the next 3 weeks, BM Sport I am no fan of, so anyone else?

Many thanks in advance,

Alex

[GaryG]

Hi I'm new to the forum
Hoping to get my X5 pretty soon
Have owned quite a few BMW and try to maintain them myself as much as possible
When I've needed jobs doing that are beyond me I have used a BMW specialist who are located near
Pratts Bottom (snigger). Is that in your area ?
I'll try and find their details
The main thing is I trust em.

[CondorX5]

The suspension on the 4.8 is notorious for its faults, just do a search on here, I have a number of threads about mine plus there are loads of others.    It could be one of many things in the system causing the problem - cheapest fix are the height sensors, may be worth swopping the sensors around to see if the fault persists on the same corner or not. 
Could also be an air bag leak (BMW insist on replacing the entire strut -around£700 a corner, but you can get aftermarket air springs -el cheapo chinese copies at about £100 each or Arnotts from the US -there are a few local suppliers who will get them, like p38spares.co.uk - just done my fronts a few weeks ago -best changed in pairs, Arnotts are around £250 each.
Then of course the compressor - seals can go, or it can become faulty -expensive. Or the suspension ECU can go faulty -again expensive.

Last year BMW struggled to repair my 4.8 (under extended warranty luckily) and total repair bills for the suspension were in the 1000's - around  £4k I think it was.    Or do yourself a favour if keeping the car long term and change to coilovers.............

[4.8iS]

Quick update:

Decided to have a play with the sensors. Both arms nearly seized solid. Took them off, cleaned and greased the ball sockets. Put them back on - same error. Decided to swap sensors - now the left hand side is back to normal and the right hand side is too low. Had a look at the voltages - front L & R were bang in the middle of the range. Rear L was also in the middle of the range, while rear R was off the scale - waaay too low. In my mind it means a duff sensor. Both appeared to have small cracks when I took them off, so will order a pair and take it from there.

Will keep you posted and thanks for the advice so far.

P.S. I hate modifying good engineering ideas - having had an E61 M5 with EDC, air in the 4.8iS is the second best thing to it. Moreover, the X5 tows the Porsches except the GT3 and the GTS, so air helps a lot.

P.S.1 New sensors ordered from the stealer - £140.14 for the pair. Will fit tonight and report on my findings. Will also take front ones off and clean arms

[Raj]

Usually when only one corner is in the air of completely down it is the sensor.

When the compressor of valve block etc go you tend to get the whole thing stuck at one height or all flat across one/both axles etc.

That's a nice collection you have too

[4.8iS]

[quote="Raj"]
Usually when only one corner is in the air of completely down it is the sensor.

When the compressor of valve block etc go you tend to get the whole thing stuck at one height or all flat across one/both axles etc.

That's a nice collection you have too
[/quote]

Thanks for the compliment about the collection... I have always been a BMW/Porsche guy. Ok, had two Mk2 Golf GTI - an 8v and a 16v, which I loved, but on the whole it has always been ///M and Porsche. When the E61 M5 was stolen, the 540i was bought for £3k with the view that I could leave it unlocked anywhere. I spent quite a lot more on the X5, looking for a low mileage car.

I bought it with 70k with FBMWSH and have done 10k in it over the last 10 months, including two trips to Chamonix and back, spectating the RAC Rallye and various races, and on the whole it has been OK. Had to replace the FSR, the engine nearly went boom as the oil pressure sensor collapsed and allowed oil to spew everywhere and now the EHCII sensors.

Luckily I am not shy with spanners, but I can see why the X5 has built a bit of a fearsome reputation. Brilliant cars, but if they go wrong, my God! It could be quite a scary experience and BMW dealers are shit in general.

Keep your fingers crossed that the sensor replacement works tonight....

[Raj]

[quote="4.8iS"]

Thanks for the compliment about the collection... I have always been a BMW/Porsche guy. Ok, had two Mk2 Golf GTI - an 8v and a 16v, which I loved, but on the whole it has always been ///M and Porsche. When the E61 M5 was stolen, the 540i was bought for £3k with the view that I could leave it unlocked anywhere. I spent quite a lot more on the X5, looking for a low mileage car.

I bought it with 70k with FBMWSH and have done 10k in it over the last 10 months, including two trips to Chamonix and back, spectating the RAC Rallye and various races, and on the whole it has been OK. Had to replace the FSR, the engine nearly went boom as the oil pressure sensor collapsed and allowed oil to spew everywhere and now the EHCII sensors.

Luckily I am not shy with spanners, but I can see why the X5 has built a bit of a fearsome reputation. Brilliant cars, but if they go wrong, my God! It could be quite a scary experience and BMW dealers are shit in general.

Keep your fingers crossed that the sensor replacement works tonight....
[/quote]

Agreed they can be very expensive to put right when they go wrong but theres a lot more that can be done by oneself to reduce the costs.

I did a one dayer to ZF in Dortmund to get the gearbox service done and really stretched her legs and she never missed a beat and went well.

Had lots of compliments taking her round Spa too at the sound she makes on full chat.

[4.8iS]

[quote="Raj"]


Agreed they can be very expensive to put right when they go wrong but theres a lot more that can be done by oneself to reduce the costs.

I did a one dayer to ZF in Dortmund to get the gearbox service done and really stretched her legs and she never missed a beat and went well.

Had lots of compliments taking her round Spa too at the sound she makes on full chat.
[/quote]

I have read on the ZF Service and I am tempted, just got to find the time to do it. Now would be perfect as the box is on 80k, which would extend its life to infinity As for the noise - totally agree. Every time I turn the key I laugh out loud. Easily one of the best sounding standard BMWs. Definitely better than my E46 M3 or E61 M5. Even my mate who has a 12C in his garage agrees the N62 sounds the bomb.

Later on this year I will be going to the Ring again and will tow the GT3 to keep the mileage low. It will be rude not earn a sticker for the X5. I am sure it will be quite a laugh. Though breaking for Schwedenkreuz, the Fox Hole or Breidscheid could be interesting... )

[4.8iS]

Sooo...

New sensor fitted and all back to normal once the fault was cleared with INPA. Word of warning - a duff sensor, which still shows voltage (but the wrong one) like mine, would not show as a duff sensor fault (Fault code 33) neither in INPA nor DIS/GT1, but you will get an implausibility error (Fault code 100).

I had to resort to old school tactics and swap them around to rule out the faulty one. Also, it is worth lifting the car and checking that the little linkages between the suspension arms and the sensors are free to move. The one on my duff sensor was nearly seized solid, despite being plastic. I believe the seizure contributed to the failure.

[Greydog]

I believe too many Dealers and well equipped Independents have been educated to slavishly believe the "mighty code reader" they often lose sight of the fact that they are often seeing a symptom not necessarily the cause, this applies to all marques I fear.
This leads to the horrendous  costs associated with the "parts swap approach" that is often the result at dealers.
The fact they are under quite often under time constraints probably doesn't help either.

I have had 2 faults flagged with the air suspension (rear only on the 4.6) on both occasions the code reader could have cost a fortune at a dealer 1. compressor not working, this turned out to be a corroded connector and a faulty 7.5amp fuse. 2. ride height issue both sensors tested OK and it turned out to be the link arms I brought replacements rather than clean and replace.