I don't think I've read this problem. My car drops an inch or two every night. I've disconnected the battery, same thing. Changed the relay, still the same thing. Ordered the shocks from Arnett. Over Christmas the car was not used for two days. Then the shocks arrived and the car did not drop or if it did it pumped itself up before turning on. Last night it dropped again. Now I'm not sure whether to install the shocks. If it has a leak they would have been down after 2 days. Any idea?

Thank you in advance.

 

Install the shocks...

This is a very common problem on XJs. Out of curiosity, how many miles do you have?

 

My 04 XJ8 drops after every shutdown. This has been "normal" for my car since new. Upon restart it immediately rises again. Never any error messages and the car drive as it should.

 

I feel like when you are in the car, you are weighing it down. If you shut the car off, and then get out, that weight is being lifted. So the car naturally rises up as you get out. To return the car to a normal level, the air suspension releases air. This gives you the impression that it is sinking as you get out. AT least that's what I imagine!

 

You don't want to overreact to changes in the ride height on an X350 during idle times. If something is broken you'll get a failure message on the dash. If you have no failure messages, then the system is operating normally. Also, disconnecting the battery does nothing except erase selections stored in volatile memory. It doesn't correct errors, fix broken things, erase codes, or reset/reboot computers.

It would be good to fully understand all of the "modes" the ACM uses before assuming there is a problem and changing very expensive parts for nothing. The ACM utilizes 5 different modes of operation based on "activity" and ride hieght is monitored differently through these modes. They are:

Sleep Mode
Preliminary
Post
Stance and
Drive Mode

It is too detailed and complex to rewrite this but I have posted complete explanations and what happens to ride height in each of these modes. The search feature should find it for you.

Also, a phenomenom for which you should be aware - In very cold weather, air pressure is often lost in these air springs causing the car to be lower over night. In sleep mode, the ACM only checks ride height every 24 hours, so, if the car was used in the afternoon, then again by next morning, the system will not have replenished air pressure in that time. Therefore, when the car is started, the system will restore the ride height which you will physically feel as the car is started and the ACM moves from sleep to stance through drive modes.

 

The car has done 59000 miles. I think they recommend changing shocks at 60k?
Brian.

 

I have replaced one shock and my car has 83K. If they don't leak...why spend that much money on replacing them?

 

Isn't it more common for the compressor to fail than the shocks themselves?

 

Have you tried shutting the car off without getting out? Look carefully at a reference point (perhaps the leaper) and notice, at least it does this on my car, that the car does not change position or hiss. It only hisses when you get out!

 

When entering the car (open any door or trunk) after it has sat for longer than 30 minutes, the ACM will switch from sleep to plreliminary mode. In Preliminary mode, the ACM will respond to any chassis weight change (such as a person(s) getting in the car) by supplying the rear air springs and maintaining ride hieght. This is a slow sensor response, unlike fast sensor in either stance or drive mode, however, both of these modes also monitor and maintain ride height, and react to chassis weight changes via fast sensor.

When you exit the car in any mode other than sleep mode (which is impossible to do), the same occurs, the ACM maintains ride height by reducing air pressure in the rear air springs. Bottom line, you really shouldn't notice much change in ride height, even when paying close attention, when entering or exiting the car during Drive mode.

 

Great information Steve11. I read your posts in the other thread (DIY air spring replacement) and it makes sense.

 

I have replaced the shocks. First one took me 3 hours, the second one only took an hour. That was my problem. One was bad but I think I did the right thing to replace both. Thanks guys for all your help.

 

Is there a way to reduce or cut out the air flow to the shocks to "slam" the car for a lowered look?

 

I think it is possible to alter the standard ride height via the dealer plug in computer.

 

You could modify the bracket that holds the height sensor and fool the system. I don't advise it.

 

Not the only way.