Rear of car dropped and very bouncy after aggressive acceleration

[zoh721]

I've searched for this issue but can't find a similar scenario. I have an 2017 F85 with 55K miles and two days ago I was merging onto the highway and accelerated aggressively (30 to ~100) and got a Chassis Function Restricted almost immediately and the rear of the car became very bouncy.

When I parked the car, the rear is sagging on both sides and won't raise after car's parked for a few days.

I was going to remove the rear tires this weekend and take a look, but I figured I'd ask for advice on where to focus. My guess is that there are sensors that are damaged?

Thanks for any suggestions!

[bmwx5er]

Your rear air springs are likely shot. I just replaced mine at 57.5k miles.

[Yuille36]

If your vehicle is sagging in the rear, the likely culprit is worn out rear air bags. They aren't very expensive to replace. The issue is that they're made a rubber and as rubber ages, they develop tiny cracks, which allows the air to escape.

[zoh721]

Thank you for replying guys.. I removed the rear tires and my air springs were completely deflated on both sides. The height sensors seemed to be connected properly and not broken. I also checked the fuses and relay and they were fine.

I then removed the air compressor and dismantled it. I followed a YouTube guide on renewing the compressor. After reinstalling it, the rear air springs have re-inflated and the car runs smoothly again. After seeing the advice here and on this forum, I will replace the air springs anyway. At least now, I can drive the car to work while I wait for the parts to come in. Turns out, I have to replace the rear brake pads anyways ☺️😃

Thank again guys!

Edit: *deep, disappointed sigh* I just saw I left out an O-ring.. will need to remove the compressor again 😞

[640ijims]

Before you drop bucks on new bags, as you are obviously a wrencher…..get under car with spay bottle with water and Dawn…shake up and spray ….watch for bubbles. If leaks apparent replace…if not wait for bag failure. I had one go at about 50k, the other is still going strong