LX570 08, AHC Impossible to fix!!

[Falmin]

Hello friends, I bought an lx570 2 months ago, it was really bouncy but I thought it was a good deal. i have spent nights trying to find the issue, I read hundreds of posts but non of it works for me.

My problem is with the rear suspension, it bounces on speed bumps if I go slow, slams hard if I go a bit quicker. On highway it feels like micro bouncing on every imperfection on road. The crazy part is that it does get better like brand new ride but then gets worst, all randomly whenever it wants. The height works, pressure all good. Tech stream has no errors. Every 7 out of 10 times, it'll slam, the other times it drives like in clouds. So strange.

Things I did to fix it but failed:
-4 new globes
-4 new struts
-4 New tires
-Multiple bleeding/Flushing
-30mm spacers
-increasing the rear height
-resetting g sensor, steering etc.

Multiple shops said it had no issues but I think they simply refuse to invest time in finding the problem.

1 thing I noticed was whenever it was working bouncy, driving on rough road hard made it factory again but 10 mins later it's rough again

DI'd anyone face similar issue?

 

[grinchy]

Sounds super frustrating!
I’d remove any plus height adjustments at the height sensors.
Does it go into L and H?

Assuming all that is fine, it sounds like air in the system.

 

[Sandroad]

I really can’t help with AHC, but I seem to remember some time ago there was an issue with contaminated AHC fluid in factory containers. I wonder if those chunks of contamination got into the system and could cause intermittent problems?

 

[TeCKis300]

Definitely frustrating. There's quite a few more parts to the system and any if these could be at fault. Based on your symptoms, focus on the rear components. Sounds like your dealing with damping issues in the rear which is the responsibility of the "No. 1 Gas Chamber" assembly. The globes provide compliance, but it is the component that it is screwed into that actually provides damping with internal spool valves and adaptive orifices.

 

[Falmin]

Sounds super frustrating!
I’d remove any plus height adjustments at the height sensors.
Does it go into L and H?

Assuming all that is fine, it sounds like air in the system.

I tried stock height as well, the rear just isn't stable at all. Since I didn't have 3rd row seats so I put 115lbs of weight, plus I made the fuel tank full, made the tire pressure 36 instead of 33, it drives some what better now. Still feeling bumps time to time.

 

[Falmin]

Definitely frustrating. There's quite a few more parts to the system and any if these could be at fault. Based on your symptoms, focus on the rear components. Sounds like your dealing with damping issues in the rear which is the responsibility of the "No. 1 Gas Chamber" assembly. The globes provide compliance, but it is the component that it is screwed into that actually provides damping with internal spool valves and adaptive orifices.

View attachment 4013886

Okay, how do I check those? They look ok, no rust and no codes. There is 4 things in total, the rear sensors, the rear gas Chambers. All 4 expensive items, so I wanna be somewhat sure.

 

[grinchy]

Is his a side to side sway or an up and down issue?

 

[Falmin]

Is his a side to side sway or an up and down issue?

Side to side and up/down is very great. It's the rear that is very rough to drive. On speed bumps the rear keeps slamming, on highway rear feels like school bus suspension. Instead of absorbing bumps, the rear moves in motion of the bump.

 

[TeCKis300]

Okay, how do I check those? They look ok, no rust and no codes. There is 4 things in total, the rear sensors, the rear gas Chambers. All 4 expensive items, so I wanna be somewhat sure.

I don't know that there's any useful way to test and check them other than to replace them. No one has gone sub component level on that yet. As they're responsible for damping in the rear, the lack of which your symptoms seem to point to, that's what I would attack next.

I've attached a document hoping it might give you more insight.

 

[grinchy]

Have you checked bushings in the rear. There are pan hard bar, control arm, and sway bar. Maybe look to see in those? Some of your symptoms O would associate to a pan hard bar issue.