Well, our Forum has taken a delightful turn for the better, but...

There were at least two posts lost in the balance. Oldmots was proposing the possibility that moisture retained in the receiver/ drier (now that he has told us there is one) might be freezing, explaining in part the cold weather symptoms. He also suggested that the resulting additional work the compressor would therefore be doing would increase the amperage draw and overheat the compressor relay.

Mots, if you're back on line and reading this, do you still have your old compressor? I'd like to know it the existing air drier can be somewhat easily disconnected: no need to dismantle yours, I realize it is a core return. The idea is that the existing drier could be bypassed for testing the compressor amperage drain and air pressure output before and after while still on the car, and the thought as to whether a remote receiver/ drier could be plumbed in its place if the old desiccant was in fact revealed to be restrictive.

 

Oldmots had previously mentioned, and then reiterated yesterday, the symptom of a noise he heard when walking away from his X350 after a drive. I'm paraphasing from a lost post here, but his suspicion was that the compressor has a relief valve which was "popping off" and that this was a symptom he had not experienced when he first owned the car.

That being the case, I would speculate that the compressor had reached a predetermined maximum pressure and was heat soaking after the car was shut down. Perhaps this pop-off is occurring while driving , but is not audible at that time. There should be a way to monitor this event, as Mots indicated that the valve was electronically controlled: perhaps someone with a C code index for 2004 X350 could look and see if such ECU monitoring is present.

Another poster had been asking about Air Conditioning system pressures in another thread, and it bears some similarity: a blocked receiver/ drier results in high discharge side system pressure, and can make that compressor pop-off too.

Hopefully this is starting to make some sense as to why the "Seeking answers" is worthwhile. Some owners and observers might dismiss potential CATS system failures as "the nature of the beast", or as an inevitable consequence of a sophisticated system. Compressors, relays, air struts and other system components will have a maximum lifespan to be sure, but anyone who owns a car out of warranty, or is contemplating such a purchase, deserves every reliable mile the components and the car can provide.

So Oldmots has provided some very helpful direct experience towards the troubleshooting, and I'm still back to the beginning: doesn't the system require a functioning and non-restrictive receiver drier, and wouldn't preheating and maintaining a constant inlet air temperature for the compressor improve system efficiency and perhaps component lifespan?

I still don't see a direct link between compressor function and the problems with strut leaks, particularly in cold weather. A car that sits outside in freezing weather is still going to drop if O rings cannot effectively retain air pressure when contracted. Preheated compressor air will help the system to recover faster, big deal. So the air leaks are not directly related in my mind, unless the reservoir pressure is already too low when the car is parked, or that correct air pressure to the struts is somehow impaired due to icing...from moisture that isn't supposed to be present.

The comparison to servicable Land Rover driers seems completely relevant. Either the deasiccant effectiveness is reduced over time permitting moisture ingress, or its effectiveness eventually creates a restriction to airflow. That's why those guys can buy new beads and replace them. So measuring the possible effects of a restricted air drier and bypassing it to an accessory unit if necessary seems the next logical step.

 

A few thoughts on this. Today, after shutting off the car with the new compressor, I heard the popping off sound from the compressor relieving air pressure just like the old one did. This must be normal. The container that I think is the drier does not appear able to be bypassed or removed easily, it seems built onto the compressor outlet with no connectors in between the compressor and the container. It looks to me like changing the drier is also not an easy thing to do. I have taken pictures of the unit and sent it back, so I will try to post them later. The compressor cylinder head and the drier are connected directly and I saw no fasteners to allow pulling them apart. They look to be pressed together. The unit does not look service-friendly, with rivets and pressed parts and very few connectors of any kind. Even the plumbing is pressed plastic that looks heat shrunk together without clamps and it is pressed into grommets in the head and valve body that look like they are difficult to pull apart. Trying to remove it will probably damage it. All this is telling me that getting a kit of parts to fix this thing at home is not high on the likely meter. If I had to guess, the current system of having them rebuilt by Jag is probably the future of it.

 

Thanks Mots,

Pics will be appreciated, but you've painted it well already.

So what's up with the pop-off? And by any chance have you had codes checked with IDS since the problems first appeared? Maybe a previous code would mean something, I don't recall if you had posted anything on this subject or not.

Overall, not good news for the "let's fix it" side of the ledger. And as you noted, the rebuilt unit pricing is headed in the wrong direction.

 

Maybe the pop off is the reaction to my 190 lb butt getting out of the car and the suspension needing to lower slightly to maintain level. The only way it can lower is to let some air out.

 

Hello there
I've a 2004 XJ, based in the UK, temperature recently 3-10 celcius. And I have an Air Susupension Fault...
[sounds like the intro at some councelling meeting - I suppose it is, really]

Owners seem to suggest that the error message is shown if the required pressure is not arrived at within a given time frame. My home-made test runs have shown a distance related cause and not a time related one. Having run many trips defining what affects the message in my car, my sub-conclusion is different from those posted here. I have considered ambient temperature, distance, time, idle-time before moving, etc..

I understand we have been given information that there is a timing test on the car by the ecu after start up. Maybe I have a different fault to each other driver. In any case, I thought my details may prove interesting or useful. I have not had the car tested for the all-important error codes.

The symptom is, after almost exactly 0.4miles, the error message appears. There's an approximate 50:50 chance whether it will or not. After appearing, if the engine is switched off an on again, the message immediately repeats itself. However, if the power cycle has a twenty minute break, then we are back to the 50:50 chance again.

I have considered the following factors, none of which appear to change the 50:50 situation - Please note, this appears to differ from the stories on this thread.

1. Ambient temp < freezing
2. Ambient temp 3-10 celcius
I've had the car since the summer months, where I didnt see the problem.
I dont know if this was because the problem hadn't developed,
or because the weather was slightly warmer.
3. Drive away immediate after starting engine
4. Idle for 30-60 seconds before driving
5. Idle for 5 minutes before driving
6. drive <10mph for the initial 0.4 mile
7. drive 50mph for the initial 0.4 mile
[checking if time or distance related. Result = distance]
8. Swapping the #4 relay for an identical one in the same "junction box"

Do I have the same compressor problem, or is this unrelated? If you wish I will take this matter to a new thread if you deem necessary. Otherwise, I'd be interested in your collective thoughts.

 

Greetings HBZ,

Nice intro! Thanks for taking the next step in your program here.

I know nothing beyond the information in this thread. There is a much more informative one which began on 4-19-08 by datekho, you may want to compare notes with the entries that follow.

As for your particular symptoms, I wouldn't draw any conclusions without first having the Diagnostic Trouble Codes retrieved at a Jaguar Dealership. Please follow up with any information you learn for the benefit of others.

 

Can you tell me what relay, is the compressor one. The dreaded, "air suspension fault" is on again. Get in start off, no problems, stop at shop, do shopping, a few seconds after start up, the fault shows. No other problems.

 

And where is the diagnostic plug, had a quick look, no can see.

 

The OBD2 connector is in the driver footwell next to the console.

 

Heaven,

Your code reader isn't going to read air suspension fault codes,

As for the compressor relay, here is as much as I know, courtesy of jag_genius:



04-19-2008, 10:41 AM
jag_genius
Join Date: Jun 2007
Posts: 1,826

RE: Air suspension fault

--------------------------------------------------------------------------------

yeah it will save a code.. C2302 plausibility fault under air suspension.. it can need a relay #4 under the hood in the fuse box p/side or may need a compressor.. which is very common.
__________________
Jaguar Master Tech
ASE Master Tech

 

OK, The diagnostic plug, just wanted to know where it was for later. Hope it is not the Compressor, it has not turned over 30.000 K yet, That would be poor. So if I wanted a new or refurbished one. Where would be the cheapest place to get one,"talking importing one". It seems funny, that on first start up, you would think then, if it was the compressor. but I can drive around for a week, all is fine. then on the forth time out, on the same day, the fault occurs. Then goes away again.

 

That's why when ypu first posted your symptoms a few weeks ago, I suggested testing the relay. Your problem on hot restarts doesn't seem like it would be caused by a compressor fault.

 

Hello!

I've not gone through the whole forums, but going to do it now!

I have the same problem... Still have it... Seemd like it was solved by covering the compressor, but not... It was just not cold enough the last few weeks. Now it's under 0C degrees and the car cannot be used outside the city. I went to a 150km trip last week and it was a nightmare. Under -5C degrees the whole trip and I had to stop every 10km to let the car lift up.... It's impossible to use it, so I'll print this thread and take to the dealer as they have no idea what the problem an be....

 

Well it never freezes here, normal lowest it get is 10. normally 15 to 35. And I get that fault showing, with only 26 thousand K on the clock. Waiting for a new relay, hoping that's what it is.

 

Seems the compressor, has a thermal overload, that shuts down the compressor, so it won't get to hot. This is in the two minute run time of the compressor. And it has a desiccant, that is self drying, the air is vented through the desiccant at low pressure, it gets this air from the air springs.

 

The units available are all rebuilt as far as I know. Even the dealers are selling rebuilt, at least my dealer is selling rebuilt ones. I would not expect them to last any longer than 40,000 miles. I got one from online for $475 which was far less than the $900+ quoted by the dealer near me. It took about an hour to install it in the driveway. About two months ago they were selling for $278! I have had noisues with my car save this one, if it costs a few bucks every 40K, it doesn't bother me too much. Air suspensions are a pain and this one has its issues as do all the others.

 

All my air suspension experience is with the Land Rovers. The EAS system on them has 1 very common failure and that is the springs themselves, after that is the valve block followed by the compressor itself. Although from my experience the compressor usually lasts at least 100k.

Here is the basic operation of the Range Rover EAS System

Air Suspension Details Overview
The electronically controlled airbag suspension used on late model Classics, the Range Rover 4.0/4.6 and theMk III Range Rover gives the vehicle a low profile for high speed handling, fuel economy and safety, while allowing a higher clearance to be achieved for four wheeling. It also achieves the load levelling function by pumping air into the individual springs to maintain ride height and keep the vehicle on an even keel regardless of load.
The system uses air springs of the type used on large trucks, but specially designed by Dunlop for long travel. Air is drawn into a 10 liter storage tank through a dryer and compressor. System operating pressure is 10 bar (150 psi) for Classic and 4.0/4.6 models, and 13.7 bar (200psi) on the Mk III model. A solenoid valve block regulates the flow of air to and from each individual spring under the control of the system ECU. All exhausted air passes out through the dryer in reverse to flush it out and avoid any water buildup in the bottom of the tank.
Height sensors for each wheel (potentiometers mounted on the suspension arms) inform the ECU of the vertical position of each wheel.

Height Settings

1. Access Mode -- the lowest setting, 2.5 inches below standard ride height on the Classic and 4.0/4.6, and 1.8 inches (40 mm) on the Mk III. On the latter two models it can be "preselected" prior to stopping, and on the Mk II it can actually be activated when the speed drops below 15 mph.

2. Low Profile/Motorway -- an inch (0.8 inch or 20 mm on the Mk III) below standard; selected automatically above 50 mph (62 mph Mk III) unless inhibit switch is depressed.

3. Standard Height -- default position used in normal around-town driving.

4. High Profile/Off Road -- 1.6 inches above standard on Classic and 4.0/4.6 models; 2.4 inches (front) and 2.0 inches (rear) on Mk III.

5. Extended Profile (Classic & 4.0/4.6 only) -- 2.8 inches above standard; selected by the ECU when it senses the vehicle is high centered.
Driver and Automatic Height Controls
Two dashboard switches provide manual control of ride height settings. There is an up-down rocker switch (replaced by a rotory control switch on the Mk III) and an "inhibit" switch (renamed the "hold switch on the Mk III and located at the center of the rotary control). The Mk III also has an additional switch on the driver's door that can be used to select access mode.

On the Classic and 4.0/4.6, all height settings except "Extended profile" can be selected manually using the rocker switch. The "Inhibit" or "Hold" switch can be used to lock the height setting in standard or low profile. On the Mk III, the low profile /motorway setting cannot be nanually selected, but once it is at this height it can be held there by the "hold" switch.

The suspension ECU changes ride heights automatically under various conditions. In access mode, moving away from rest, standard ride height is automatically selected. At freeway/motorway speeds, low profile or motorway mode is selected automatically unless the inhibit/hold switch is activated. In High Profile/Off Road mode, if speed rises above about 30 mph (31 mph on the Mk III) the suspension reverts to "standard" height. On the Mk III, if the ECU senses that the trailer connector is being used, the suspension is locked into the "standard" height setting.

 

I forgot to add here is a link to the basic troubleshooting and diagnostics for the EAS system on Range Rovers.

http://rangerovers.net/repairdetails...ion/index.html