AHC is choppy when going in low. Any Ideas?

[petwhookie]

Hi all,

I am having some noise from my AHC when it's going from neutral to low.
Symptoms:

-It has a very choppy feeling and you can hear it.
-Sometimes my AHC will not engage in low if I'm on a incline.
-From neutral to high, the car goes up without any noise or issues.
-Sometimes going from High to neutral, I will feel and hear the choppiness of the system.​

Does anyone have any ideas what's going on?

 

[khoaiii]

when was the last time you flush the ahc fluid?
last weekend, my ride was bouncy on the highway for 10 min then it's fine. when i got home, i notice my ahc has difficult time going from hi to low. so i flush the ahc, much better ride now and hi to low, no problem.

 

[PADDO]

Hi all,

I am having some noise from my AHC when it's going from neutral to low.
Symptoms:

-It has a very choppy feeling and you can hear it.
-Sometimes my AHC will not engage in low if I'm on a incline.
-From neutral to high, the car goes up without any noise or issues.
-Sometimes going from High to neutral, I will feel and hear the choppiness of the system.​

Does anyone have any ideas what's going on?

Ensuring your fluid is in great shape, no air etc (i.e. regular changeouts) and neutral pressures are optimum is always a good thing. But from what you've described, noise and stiction when lowering under its own weight (the vehicle isn't driven down under hydraulic force, just gravity) I'd be very inclined to look at a propeller shaft stiction and/or suspension stiction issue. I've eliminated a similar problem to yours [I think] by ensuring the slip yokes in particular were well greased and free to do their thing as the shafts compress/expand. You can put the vehicle in AHC active test mode and control just the front or just the rear to max height or down to the bump stops to see if there's any relationship to just the front or just the rear which might help narrow things down, particularly if you can have a helper do the up/down controlling while you crawl around (safely, not under the vehicle) looking for the noise source.

 

[Julian Stead]

Agree, I had noises coming from my sway bar bushes when changing height. After replacement, it was a lot smoother with no noise.

Ps. I changed the sway bars themselves aswell due to wear in the drop link holes and also where the bar mated with the bushings was worn.

 

[petwhookie]

when was the last time you flush the ahc fluid?
last weekend, my ride was bouncy on the highway for 10 min then it's fine. when i got home, i notice my ahc has difficult time going from hi to low. so i flush the ahc, much better ride now and hi to low, no problem.

The PO owner did it. I have to look through the services records to find out.

Ensuring your fluid is in great shape, no air etc (i.e. regular changeouts) and neutral pressures are optimum is always a good thing. But from what you've described, noise and stiction when lowering under its own weight (the vehicle isn't driven down under hydraulic force, just gravity) I'd be very inclined to look at a propeller shaft stiction and/or suspension stiction issue. I've eliminated a similar problem to yours [I think] by ensuring the slip yokes in particular were well greased and free to do their thing as the shafts compress/expand. You can put the vehicle in AHC active test mode and control just the front or just the rear to max height or down to the bump stops to see if there's any relationship to just the front or just the rear which might help narrow things down, particularly if you can have a helper do the up/down controlling while you crawl around (safely, not under the vehicle) looking for the noise source.

Great idea! I will look into it.

Agree, I had noises coming from my sway bar bushes when changing height. After replacement, it was a lot smoother with no noise.

Ps. I changed the sway bars themselves aswell due to wear in the drop link holes and also where the bar mated with the bushings was worn.

Hm... bushings huh? That would be an ideal and easy fix. Thank you for the suggestion!