Suspension Question

[nyczdave]

I have a question about the x5M (F85) suspension. I haven't driven my 2018 x5M for about a month and when I decide to drive it, I found my rear suspension dipped but after starting and warming up the x5, it went back to (to what I think is the proper height). Has this happened to anyone before? Is this anything I should be concerned about? I did purchase extended warranty so if this is an issue, I would love to get it fixed while it's still under warranty.

Here are the pics of the before and after I started the car.

Thanks in advance!

[meds1976]

Assuming you have rear air suspension? Maybe the airbags deflated and then re-inflated when the compressor kicked in after you started the car up? Could be a puncture in the airbag.

[kangfu84]

Likely rear air bags are leaking and need replacing. Has happened to most of us haha

Get yourself 2 x Arnott A-2642 replacement bags and it's a relatively simple job to DIY replacement. Replace them soon though as the compressor is now stressed and can also develop issues if the bags go unaddressed (like mine did)

Edit: Forgot you mentioned warranty. Go get the bags replaced

[nyczdave]

Originally Posted by meds1976

Assuming you have rear air suspension? Maybe the airbags deflated and then re-inflated when the compressor kicked in after you started the car up? Could be a puncture in the airbag.

Everything mechanical is still stock.

[nyczdave]

Originally Posted by kangfu84

Likely rear air bags are leaking and need replacing. Has happened to most of us haha

Get yourself 2 x Arnott A-2642 replacement bags and it's a relatively simple job to DIY replacement. Replace them soon though as the compressor is now stressed and can also develop issues if the bags go unaddressed (like mine did)

Edit: Forgot you mentioned warranty. Go get the bags replaced

Thanks.. glad to know its a possible leak and not something that happens normally from not driving it for a month

[Qsilver7]

If the suspension hasn’t resettled downward…and/or you don’t constantly hear the compressor running…there’s probably nothing wrong other than you hadn’t driven the vehicle for awhile.

When you did start her up…the suspension had dropped slightly so the compressor turned on and corrected the suspension height. That’s what the system is designed to do. Since temperature can affect the air in the springs…since the car hadn’t been driven in a month…the discharge valve probably released some of the air in the one or both of the springs (especially if the ambient temperature changed drastically in the month it was sitting undriven):

Discharge valve

The discharge valve is activated by the EHC control unit. The air escapes from the solenoid valve block via the discharge valve through the air drier.

The pressure limitation function of the discharge valve limits the pressure in the air supply system as follows: Maximum pressure 13.5 bar (temperature-dependent tolerance +5 to + 6.5 bar = breakaway moment if discharge valve not used for a longer period)

Air Supply (compressor)

1. Electric motor
2. Compressor
3. Air drier
4. 2-pin plug connection for discharge valve
5. 2-pin plug connection for electric motor
6. 3-pin plug connection for solenoid valve block
7. Valve block

My e53 X5 has rear SLS and it’s always running the air compressor for various scenarios…especially if it hasn’t been driven in a while….and there’s nothing wrong with the air bags.

Again, if the compressor kicked on after not driving the vehicle for a month…and the suspension appears to be the correct height and the compressor isn’t continuously running to pump the suspension back up…then nothing is wrong except for not driving the vehicle enough.

[jab23]

Great info as always Qsilver7. When I swapped my winter to summer wheels a couple of months ago, I took a quick drive to reset the TPMS. I left on business trip the next day and came home to the rear sitting all the way down. While I loved the reduced wheel gap, I figured my bags were shot. Started the car up, the bags filled and I haven't had an issue since. Think I just confused the system with the jacking or something. All that to say it may just be a one time thing for now.

[Qsilver7]

Originally Posted by jab23

…I figured my bags were shot. Started the car up, the bags filled and I haven't had an issue since. Think I just confused the system with the jacking or something. All that to say it may just be a one time thing for now.

Yep, unless the issue keeps happening on an irregular basis….like the air bags continue to lose air daily…or the compressor is always running when there’s no normal reasons for it to be activated…then the system is probably just making an adjustment.

Take two aspirin and call back if the situation persists.

Here’s more info that explains the ten modes of the rear axle air suspension that can affect the initiation of adjustment:

The EHC control unit uses the various signals and messages to detect the various driving conditions. Depending on the driving conditions, the adapted control functions are switched accordingly.

Control functions of the single-axle air suspension are:

1. Rest state
2. Pre mode (temporally controlled pre-run / after-run)
3. Post mode (post adjustment)
4. Normal mode
5. Drive mode
6. Cornering
7. Transposition
8. vehicle hoist
9. Transport mode
10. Production mode

Rest state

The Sleep mode is the initial state for interventions. In the rest state, no controls takes place. Adjustments that were started in other intervention modes are cancelled when the Sleep mode takes effect.

Pre mode

In Pre mode (timed initial run / after-run), changes in load are equalised even as the vehicle occupants are getting in and then again for a few minutes after the vehicle is shut down. When the vehicle is locked, the after-run is shortened.

In the Pre mode, the vehicle can only be raised to its specified height if the level drops significantly below the specified height. The tolerance band for the control is approx. 60 millimetres below the mean value. The tolerance band stipulates when the electronic circuitry in the EHC control unit performs regulation. This tolerance ensures that the vehicle is only regulated for heavier loads to increase ground clearance before driving off. Smaller payloads only lead to small amounts of compression travel which are only balanced out after the engine has been started. These control characteristics reduce load on the battery. In pre-mode, only the mean value of the two ride height sensor signals is considered.

Post mode (post adjustment)

The Post mode is used to balance out any inclination before entering the Sleep mode after completion of a journey. The control function has a time limit (approx. 1 minute). In the Post mode, adjustment is made in a defined tolerance band (± 10 millimetres).

Normal mode

The Normal mode refers to the normal operating condition of the vehicle. The Normal mode is initiated by means of the 'engine running' signal. Adjustment is made in a defined tolerance band per side (± 10 millimetres, rapid filtering).

Drive mode

The Drive mode is activated in the EHC control unit when a speed signal above 1 km/h is detected. In drive mode, regulation employs slow filtering. In the Drive mode, e.g., different ride heights that occur as a result of the reduction in the vehicle mass due to fuel consumption are balanced out.

Cornering

The control function ”cornering” prevents adjustment when cornering is detected. Slow filtering is suspended and any ongoing regulation sequences are cancelled. Cornering is detected from an incoming lateral acceleration signal (e.g. cornering greater than 2 m/s2, less than 1.4 m/s2 when leaving bend). The ICM control unit sends the lateral acceleration signal via the K-CAN.

Transposition

The operating mode ”transposition” prevents balancing of any inclination when only one wheel of the vehicle drives over an obstacle. Equalisation would cause a new inclination after the vehicle is driven off the obstacle, making a new regulation sequence necessary. If the vehicle is driven onto the kerbstone and stopped, the EHC control unit will switch from drive mode to normal mode. In this control function, the signals of the ride height sensors on the left and right are evaluated. If the difference in ride height between the left and right sides of the vehicle exceeds a certain amount (e.g. 28 millimetres), switch-over to the control function "skew" takes place.

In this control function, the vehicle ride height in the middle of the axle is evaluated by the EHC control unit. If the vehicle is loaded or unloaded, the degree of rebound is considered. If the figure is outside the defined tolerance band (e.g. ±10 millimetres), modulation is initiated. The left and right-hand sides of the vehicle are raised or lowered by the same amount as each other. The difference in ride height between the two sides is retained. When the EHC control unit goes into the Drive mode, the control function ”transposition” is terminated. Any ongoing control is cancelled. The "skew" control function is cancelled when the ride height difference between left and right sides of the vehicle is below a specified amount.

Vehicle Hoist

In the control function "Vehicle hoist", adjustments due to wheel changes or repair work on the vehicle hoist are prevented. The following conditions trigger the ”Lifting platform” control function:

Permissible spring extension exceeded (e.g. more than 50 millimetres, recorded by left and/or right-hand ride height sensor)
The vehicle is raised slightly (rebound of e.g. less than 55 millimetres), the control operation starts and the vehicle is not lowered
The ride height is stored in the EHC control unit. A reset is performed when the vehicle is again e.g. 10 millimetres under this stored ride height or when drive mode is detected.

Transport mode

In the Transport mode, the nominal height is raised (e.g. 30 mm). Increasing the ground clearance ensures safe transport of the vehicle.

Production mode

The Production mode is used for assembly on the line and prevents regulating operations.

[640ijims]

Take it to a shop that accepts your warranty. They will “soap” bags and fittings and look for one leaky bag or leakin fitting. Them you and they know what is problem, whether covered by your warranty or not is the question.

[nyczdave]

Thanks for all the great info.

Originally Posted by Qsilver7

If the suspension hasn’t resettled downward…and/or you don’t constantly hear the compressor running…there’s probably nothing wrong other than you hadn’t driven the vehicle for awhile.

When you did start her up…the suspension had dropped slightly so the compressor turned on and corrected the suspension height. That’s what the system is designed to do. Since temperature can affect the air in the springs…since the car hadn’t been driven in a month…the discharge valve probably released some of the air in the one or both of the springs (especially if the ambient temperature changed drastically in the month it was sitting undriven):

Discharge valve

The discharge valve is activated by the EHC control unit. The air escapes from the solenoid valve block via the discharge valve through the air drier.

The pressure limitation function of the discharge valve limits the pressure in the air supply system as follows: Maximum pressure 13.5 bar (temperature-dependent tolerance +5 to + 6.5 bar = breakaway moment if discharge valve not used for a longer period)

Air Supply (compressor)

1. Electric motor
2. Compressor
3. Air drier
4. 2-pin plug connection for discharge valve
5. 2-pin plug connection for electric motor
6. 3-pin plug connection for solenoid valve block
7. Valve block

My e53 X5 has rear SLS and it’s always running the air compressor for various scenarios…especially if it hasn’t been driven in a while….and there’s nothing wrong with the air bags.

Again, if the compressor kicked on after not driving the vehicle for a month…and the suspension appears to be the correct height and the compressor isn’t continuously running to pump the suspension back up…then nothing is wrong except for not driving the vehicle enough.

[Qsilver7]

[nyczdave]

So it happened again and this time my driver side suspension isn’t lifting in the rear.

After starting the x5 and letting it run for about 10minutes my suspension just sits low now on my driver side only.

Has anyone have their suspension replaced recently? Assuming that’s what I will need to do. Anyone know the ballpark figure this may run me?

I have an appt with BMW Rallye at the end of January so trying to brace myself for a hefty bill.

[Yuille36]

9 times out of 10, it's your rear air bags. As they age, they develop tiny cracks that allow the air in them to leak out. You can try spraying them down with soapy water, if tiny bubbles appear, then you will know their leaking. But the air bags are relatively cheap, if you purchase from an outside source other than BMW. Labor is roughly two hours.

[lemonslap]

Just had both my rear airbags replaced at 37k miles on my late 2018, only one was leaking however both replaced under extended warranty. Only dropped sometimes, wasn’t down every morning but seemed worse in cold weather

[aussiem3]

I have had the rear dropping over a week - identical on both sides. I was told that this may happen if the car goes into storage mode. I then hooked up a trickle charger for a week and monitored and the rear didn't drop.

But when not hooked up to a charger it drops at the rate of 2-4 mm/day. Sometimes, it doesn't drop. I am confused as to whether this is the airbags or a loose connection in the compressor.

I am thinking of replacing the bags given the car is now coming up seven years. When the car returns to the normal ride height 804 mm (?) the compressor cuts out, which means there is no continuous bleed.

[aussiem3]

So I had my airbag suspensions replaced over the weekend with Arnott airbags. The pressure drop is same as before and is gradually decreasing. Any thoughts on what this may be ... faulty compressor or air lines?

[hitster]

I had the same Intermittent sagging issue, except I stupidly did not getting around to replacing the bags.

I finally managed to get my extended warranty to cover the bags (via the dealer) and was good for about a month, and just a few days ago it’s rock bottom again but this time the compressor seems to be running but not inflating either side at all.

So, lesson learned…. dont wait too long to get those faulty bags replaced!

Technically, it could be one of the components around the compressor, such as the discharge valve, waiting for the dealer to figure out what’s next.