Well All,
I've been thru so many forum posts on this issue and I think I'm more confused than before reading them. I have a 2009 VDP and 5 years ago before I sold the car (I have since Oct 2022, bought it back) ,the car would rise when I turned the engine on. Now it just stays in the up position all the time, engine on or off. In the posts, I saw statements about the control module shifting between firm and soft mode. Car seems to be in firm mode all the time. I only drive the car in the city, no sport driving for me. Is there a way to test the module? Car has 30000mi/50000kms on it.
Measurements from hub center to lower wheel arch is as following;
FL - 370mm FR - 360 mm
RL - 375mm RR - 360 mm

Thank you all for your help.

 

Hi Vinnyboy,

I have moved your post to start your own thread to discuss your unique issues. Since, when you owned the car before, the suspension would drop when the engine was not running, but now that you have re-purchased the car it no longer drops, it seems reasonable to assume that some work has been done on the car while it was not in your possession.

Have you checked to see if one or more of the air springs/dampers was replaced, and if so, was it replaced with an OEM Bilstein unit or something else, such as units by Arnott Industries, Suncore, Strutmasters, etc.? One possibility is that aftermarket air spring/damper units were installed that do not support ECATS adaptive damping.

Another possibility is that the suspension was converted to conventional coil springs/shock absorbers, which is easy to check by looking up into any wheel well above the tire.

Cheers,

Don

 

Thx Don,

Had the car on hoist for an oil change and noted that all air shocks are original. I know the fella that had previously owned the car for the past 5 years and the only thing he did was to replace a front headlight. He had only drove the car about 10000kms while he had it.

 

2003 xj8 with 355.t km 220k miles with the 4 sensors and headlight leveling.
since yesterday mine rose up to about 410mm and is super stiff . Original Bilstein airsuspension .
First thought is the heightsensors DEFECTIVE so it goes into safety -transport mode.

 

Lhd
400mm FL
405 mm RL
430mm FR
460mm RR
Batterie unplugged . Lets see how much she goes down in 12hours

 

One common issue is that the exhaust solenoid valve on the air compressor corrodes and seizes or fails and can no longer open to relieve excess pressure from the system. The exhaust valve is the only point in the system where air is supposed to be able to escape. You can do a basic test of the valve without removing the compressor by disconnecting the electrical connector and applying voltage to the solenoid coil with a 9-volt battery. You should hear a "click" sound if the coil is good. I have not found a source for new replacement exhaust valves, so if yours fails, you may have to find either a good salvaged compressor or a new aftermarket compressor.

Cheers,

Don

 

Also, if you can find someone with a laptop and the SDD software, scan for codes and see if a P1582 code is logged into the event recorder ("flight recorder") function. If there's been an evap or misfire code along the way, or some event that affects starting, it'll log that code and put the suspension into default/firm setting.

Plug in the firm ride symptoms into the diagnostics menu, and it'll give you that option to look and clear codes in the flight recorder.

 

thanks Don

My compressor is fairely new like 2years old Arnott Wabco.
but i have been driving a lot even during those not that cold winters.
i consider looking at that too I know what part you describe

 

Thanks
yes that seems to clear more and more. Depending on the problems those cars are having you will get trouble with stiffness . Mines not the only one jumping into transport / safety mode Indeed I have the evap code coming up again.
will not have the opportunity during next week to deal with it but will get to it.
Now that the batterie is unplugged the airsuspension drops very slowly but consider barely any leak.

 

Well 'Petz", what happened when you disconnected the battery , results and heights , and what were the results and heights after you re-connected and drove the car?
thx

 

The air exhaust valve has another purpose, which is to exhaust air to atmosphere via the dessicant chamber to blow the accumulated water out. When I had an X350, I u sed to ocasionally hear a "woosh" on shutting the car down after a reasonably long run. My own view is that CATS is a complete wast of time, and a completely unnecessary complication on al already complex car. Having said that, I never had any trouble with the air suspension on t he two X350s I owned, (one was the later X358 restyle job).

 

Help me understand: why would anyone wants to dry air before axhaustuing it? I want to believe I missed something. Can you @Fraser Mitchell clarify, please? Drying air before it gets in pressurised environment makes perfect scense...

 

The old compressor was so wet inside beads where dark brown and wet.
i will not find the time since I am leaving tomorow . But I ll report back.
48 hours car barrely dropped without cats adjusting height

 

The desiccant is supposed to adsorb moisture from the ambient air as it is inhaled into the air suspension system by the air compressor. From time to time, the Air Suspension Control Module (ASM) commands the exhaust solenoid valve to open, allowing some of the "dried" air in the air suspension system to backflow through the desiccant bed. This is supposed to partially reactivate the desiccant.

In practice, the desiccant beads eventually encounter so much moisture that they become waterlogged and the "reactivation" procedure does little if anything to dry the beads. This is why I and many other members have replaced the desiccant beads when we replaced the piston ring/seal.

mhamilton and I were discussing this procedure and while reviewing some Wabco training documents, I was reminded that for some of their air brake systems they state that the desiccant may need to be replaced every two years. The desiccant for those systems is packaged in a spin-on canister similar to an oil filter. Unfortunately, Wabco made no provision for easy replacement of the desiccant in the compressors it designed for Jaguar/Audi/Porsche etc.

Cheers,

Don

 

So with a couple of minutes time today, here's what happened
X350 2003 Lowered irregularly from stiff and very high over 60 hours like in total 5mm on the four corners while battery unplugged.
voltage batterie 12.37V after 60 hours unplugged 12, 30 V after connection
on the ground studs in the boot it was 12.03V after connecting .
then car dropped down to 410mm ( 460before) right hand rear.
Started engine for 5 min ended up with about correct height around all corners 400 mm wich is too high I know
We had to raise it about a month ago from 386 and 375 to to 400 be able to get it into the garage entry .
drove fine with that until 3 days ago.
Sdd will be connected in about a week . Did not have time to test suspension comfort.
once in a while I sat on the open boot edge car went down to raise 3 seconds later.
so far so good

 

Thank you, Don for detailed explanation. Revitalizing descicant by shaking it up, hm, what they will think of next? More like trying to utilise every square micrometer of surface... Mine kit from BagPipingAndy had bag of descicant.

 

I probably have a kilo of desiccant left

 

Wabco provides plastic bags in 1,5 or 2 liter of beads but probably only for professional businesses .

 

we had a discussion about the humidety in the beads too.
you know what mine is now two years old I am going to open up the wheel well anyway for the compressor exhaust valve test . I should just exchange the beads and spread the old ones on cardboard take a picture and send.
Did approx 25 tkm so far also drove during winter

 

Well folks, I'm starting to buy into the 'time wears all' theory. Time makes the rubber less flexible and the 7 yr old tires harder. Other factors mentioned above would seem to apply to a high mileage car I would think. I don't want to jinx any of the components until it becomes more obvious of the source problem. I appreciate the minor maintenance such as the compressor filter cleaning and maybe the desiccant bead replacement.