BurtonLX

Hi. I bought a 2000 LX in 2008. It has 80,000 miles and it's been a great car.

I am looking for some help troubleshooting an AHC problem.

Since I bought the LX it has had a very stiff ride. Not bouncy, but stiff -- almost as if there is no shock dampening.

The car isn’t used off road, doesn’t tow anything and isn’t used to carry unusually heavy loads.

I have installed new Michelin LTX tires and I keep an eye the tire pressures, but the rough ride remains. I think I can rule out a tire problem.

The AHC system goes from normal to high and low without doing anything unusual. The AHC fluid moves 9 notches on the AHC fluid reservoir from low to high height. I think I can rule out an AHC pump problem.

The LX sits normally, not low as I've read can happen when the accumulators go. And when I press down on the corner of each bumper, the suspension moves and rebounds as you'd expect. I've read that if the accumulators are bad the suspension won't move much. Based on what I've read I think I can rule out an accumulator problem.

On to the AHC fluid: at the normal height setting the fluid level in the reservoir is a couple of notches below the minimum level. I asked my dealer last year if the AHC fluid should be flushed. He said no, unless there's a problem. But I just noticed that the owner's manual recommends the AHC fluid should be changed at 60k miles. I have all of the service records for this LX and the AHC fluid has never been flushed. Is it possible changing the AHC fluid or at least filling the reservoir to above the minimum level will help the ride quality?

I (mostly) understand how the accumulators work. Is it possible that the shocks on the LX are bad based on age and / or mileage? Do the shocks on an LX470 with AHC do anything for ride quality?

If I have bad height sensors would that cause a rough ride?

Finally, if the suspension was out of spec could that be the problem? For example, could the neutral pressure be set incorrectly or the torsion bars not be tightened properly?

I don’t have a ton of confidence in my dealer since they didn’t know that AHC fluid should be flushed at 60k miles, and they never added AHC fluid to the reservoir even though it’s below the minimum level. If I can get some troubleshooting advice from you all then I’ll be able to steer them in the right direction. I don’t want the dealer to randomly start changing (expensive) parts without properly diagnosing the problem. Thank you.

makulaf

I am not An expert but since no one else answered here is my theory from wht i have found so far messing around with mine. The accumulator supports approximately 40% of the vehicle weight. There is a diaphram that seperates the ahc fluid and the nitrogen filled section (which provides some give tht the ahc fluid does not have in your supension system) in the accumulator. If the diaphram breaks down, the naccumulator fills completely with fluid; w/o the nitrogen section, there no longer is the 40% support from the accumulator, just a system full of ahc fluid. Perhaps yo ur accumultors really are bad, your pump just fills the system with fluid raher than having a section that has a little give in it(the nitrogen filled section).

Anyway, just my theory. You will probably get a little more help over at ih8mud.com, there are several threads there on the ahc system.

V8_Fan

I suspect the accumulators are going. You could try to flush the fluid and see if there's any difference. When I lived in AZ, I flushed mine at 30K intervals due to the heat. It's around $300 for a flush (about $50 for a 2.5L can; you need 2 cans plus ~1.5 hrs labor). When my AHC goes, my plan is to install a stock landcruiser suspension. You can get the parts for around $1200 (rear coils springs, rear sway bar w/ rubber bushings, front torsion bars, shocks).