I played a card the other day, one I had held up my sleeve for 18 years. The following letter was sent to a fully accredited shop foreman at a Jaguar Dealership for his review and comment. I had at least some small role in his training back in the day, and have been waiting for a compelling enough reason to seek his assistance until now.

After reviewing the text and discussing it with associates, he has given his seal of approval to the information and theories presented. There still remains a discrepancy with the specifications cited for compressor run time vs. system pressure and DTC initiation, but the basic principles of the suggested modifications remain valid.

With his concurrence, he has forwarded the letter to Jaguar Service in its entirety. We shall see what gets though the filter and into the car.


CATS suspension reliability, 2004 Jaguar X350

Author: Andrew Bernstein
January 21, 2009


There are several message boards for Jaguar owners on the internet, and I regularly browse entries to learn as much as I can and contribute when appropriate. Recently, I have read several accounts from owners who are experiencing CATS system faults in cold weather climates. The following letter is a summary of the information I have reviewed, and my suggestions for remedial action.

The first report that came to my attention was made on January 14, 2009 by Atilla Stefan.
Mr. Stefan is the owner of a 2004 Jaguar XJ8, and resides in Budapest, Hungary. Following is a relevant excerpt from one of his submissions:

"I have these problems in cold weather, now we have under 0 Celsius during night and day for at least two weeks. My car is parked in a garage, and not problem with the lifting at all. But when driving in the cold and when parked in the freezing cold for a few hours, the car becomes a nightmare!!!"

After this post appeared, a response was entered later that day by Pavel Zvonicek. Mr. Zvonicek is the owner of a 2004 Jaguar XJR, and resides in Prague, Czech Republic. Following is an excerpt from his submission:

"This is weakness of Jaguar. This only happens to me when the car is frozen between approx. <-5, +4> degrees of Celsius. The air compressor pump is frozen and does not produce enough pressure to fill the reservoir. Either replace the air compressor or wrap it in warm plastic/leather or other cover from warm material. However I believe you do not get this message if the car is started in warm garage and you start moving the vehicle after approx 30 seconds. If you have this message in these circumstances as well (if the vehicle is warm), the problem must be elsewhere. I figured out this problem on my car as well and this was the solution."

Editorializing and speculation aside, prevailing ambient temperatures and resultant system faults are apparently common to both of these owners' Jaguars. Mr. Stefan added the following information in a subsequent post on January 17, 2009:

"I've covered the compressor with warm "covers" and gone to a 200km trip. It did not loose pressure. Hope it works, but I'll have to try it in freezing cold to be sure, as it was 0 Celsius during the trip."

As an independant Jaguar technician, I am sadly deficient in my knowledge of, and experience with, systems and features on contemporary models. I have no experience with CATS system diagnosis or repair. However, as my repair shop is located in Ohio, I know something about cold weather.After reading Mr. Stefan's report of his temporary solution, I posted the following entry on January 17, 2009:

"Great news about the suspension...maybe an electric heating pad for those of us in cold weather is the best way to keep the compressor happy overnight."... Continuing...

"A question for anyone reading this who is familiar with the system...is there any sort of moisture trap installed? Even my shop air compressor will freeze an air hose shut in this weather, and that hose I.D. is alot larger (I assume). If not, maybe the addition of a trap to collect the water would help prevent the problem."

Simplistic thinking, but the question of ambient temperature surely has an effect on system operation. Perhaps this is a pattern that you have seen many times before. So my conclusion was that either the compressor and/ or valve block efficiency was reduced by the 0 degree C temperature, or by moisture within the system that was obviously freezing in these conditions.

Several contemporary Jaguar Dealer technicians participate in the forum from which these excerpts have been taken. One individual by the name of Joe states that he is a 12 year member of the Jaguar Master Guild, and is employed at a dealership in the northern U.S. On January 20, 2009 I posed the following questions to him directly, during a different discussion on the same subject:

"I don't know JACK about CATS. But recent threads point out problems more evident when ambient temperatures are below freezing. Is there a desiccant in the system, and if not, would it be feasable to install some sort of drier or water trap to eliminate the possibility of icing?"

Here is the response I received from Joe later that day:

"There is an inlet air filter about the size and shape of a generic white plastic fuel filter(2" diameter x 4" length 3/8" hose connections) but it does not contain a dessicant. The compressor draws inlet air from behind the front bumper cover through the filter and into compressor. There is plenty of room for a bigger filter and I suppose you could add a dessicant but I would wonder about the life expectancy of the dessicant itself. It would be like putting a dessicant on your shop air compressor, it wont last long. The engineers should have put a drying system in in the first place but then the bean counters got a hold of the plans and that was the end of that. Jaguar is rebuilding these compressors now so the price has come down a lot but I still wouldn't call them cheap enough where you could stash a spare in the garage. The plausibility fault code C2302? is set simply by a timer program. As the compressor ages and gets weaker it takes longer and longer for it to build pressure and level the suspension. After the compressor runs for a certain amount of time the height is checked by the module and if it hasn't reached proper ride height the code is set. The combination of weakening compressor and cold inlet air just makes the problem worse. I am surprised jaguar hasn't come out with a reflash for the suspension module that extends run time before self testing by 15 seconds. That would probably eliminate at least 50% of the failures or at leas push them back another 15k miles. Not that that's a fix but it would certainly save jaguar a lot in warranty repairs. Almost none of the cars I've put compressors on actually had a ride height problem, just the code and message."

I have since read that the fault code will be flagged if the system pressure does not reach 14 bar in three minutes. That discrepancy aside (which he subsequently corrected), I expect Joe's information is otherwise accurate, particularly as it pertains to the lack of a dessicant or moisture trap in the system.

Apparently this points out a difference between the CATS system and the EAS system as fitted to Rover vehicles...contemporary models with which I also have no experience. I began some preliminary research and found the following information on the "Rover Solutions" website:

 

CATS suspension reliability, 2004 Jaguar X350

Author: Andrew Bernstein
January 21, 2009

.....CONTINUED......

From the "Rover Solutions" website:

"The air dryer is bolted to the side of the engine air filter housing, remove it and the 2x 8mm lines. Unscrew the top, sometimes a strap-wrench is needed to get it started.
The old dsiccant is basically sand, so it can be poured into the trash. New desiccant pours in, pre-measured. The new desiccant is made of smaller beads for more efficient filtering and drying of the incoming air. Put the felt filter then metal screen in, replace the spring and screw the top back on."

So at this point, my understanding is that moisture filtration is a significant concern for Rover air suspension systems, but is not considered to be a significant concern on similarly equipped Jaguar vehicles.

The issue of moisture in the CATS system leads me to the following questions:

Is the wear rate of the air compressor, or other system components, affected by the presence of moisture?

Is moisture in the system creating operational faults with the control valving or compressor, or otherwise impairing system eficiency, when low ambient temperature causes this moisture to freeze?

If moisture is not in fact a significant concern, will simply raising the inlet air temperature of the compressor at start-up in cold climate conditions help to alleviate the symptoms reported?

Again, I am not familiar with the hardware or software details of the CATS system. The first question could easily be answered by installing a desiccant device to prevent water ingress. It is logical to assume that subsequent testing would quickly answer the question of icing.

If moisture and resultant icing is not identified as causal, my next effort would involve raising the compressor temperature at start-up. The suggestion of a heating pad is not likely to be considered a satisfactory solution by many owners!

One possible way to achieve this goal would be the addition of a "preheater" pipe for the compressor air inlet. My concept for this would be the addition of a heat shield installed around one of the catalytic converters, to which a pipe is attached and routed through a relocated air filter and to the compressor inlet. This "heat stove" method would be a simple way to increase compressor operating temperature at start-up. A "switching valve" would be required at the compressor to close this preheated air supply, and a supplementary timer relay or signal from the system control module would be required to activate the switching valve at some undetermined length of time: perhaps three minutes in ambient temperature below 10 degrees C would be sufficient. That timer is already integrated in the system control module, from my understanding.

The only other concern would be a temperature signal to inhibit switching valve operation on hot restarts. Melting the compressor won't work any better than freezing it apparently does.

 

CATS suspension reliability, 2004 Jaguar X350

Author: Andrew Bernstein
January 21, 2009

.....CONTINUED......

So with compressor temperature at start-up improved, and moisture filtration added if necessary, what about the air inlet under normal running conditions? I would explore the possibility of drawing compressor inlet air from the vehicle's cabin. Why not allow the compressor to "breathe" the same filtered, dehumidified, temperate air that the driver enjoys? In addition to raising and stabilizing the compressor temperature for low ambient conditions, the converse would be true: I don't know if excessive heat in high ambients is a concern, but that possibility would be positively affected as well.

The complexity of acheiving this goal is something you know more about than I do. My theorized example would eliminate the existing front bumper inlet entirely. I would route a hose to an existing climate control duct, at the rear console area if feasable, and back to the compressor. Attach that hose to the added "switching valve", through the relocated air filter, through the desiccant bottle (if necessary) and to the compressor. The added preheater pipe connects to the other port on the switching valve, and no other modifications are forseen as necessary.

That sounds to me like warm, dry air at cold-startup... and temperate dry air during all other ambient conditions. That sounds to me like it would reduce or eliminate the faults Mr. Stefan and Mr. Zvonicek are dealing with, and hopefully have a positive effect on the compressor's durability overall.

The projected cost to engineer and install these modifications does not strike me as being prohibitively expensive. As a former Jaguar certified dealership technician, I can recall performing rather extensive Product Quality Updates on previous Jaguar models: some were far more expensive than my proposed modifications, and had far less to do with vehicle safety and reliability.

Brand loyalty and the "preservation of the species" are topics of great importance to me, and to others who participate in public discussions about their present and future Jaguar ownership. The subject of CATS system reliability is often mentioned, and has engendered some reluctance among current and prospective X350 owners. I'd like to see an end to that discussion.

Andrew Bernstein
British Auto Care

P.S. Thank you to all who have contributed to these discussions to date. I am keenly interested in additional comment from those with directly related experience, and from those with the engineering acumen to identify perceived flaws or recommend additional detail to my
proposals.

 

Bump.

Have a look please, R_T and anyone else with interest (and patience).

 

Last bump.

_genius, please have a look and share your thought if the mood strikes you. Thanks.

 

I just read you entire post, thanks for sharing this with us.As a new X350 XJR owner (purchased this wk) I look forward to seeing what comes of this; hopefully Jaguar will acknowledge this potential issue and take the necessary steps to ensure their customers are well taken care of in case anything bad does happen.

 

Thanks for taking the time to review and respond, I really appreciate the input. Advocacy for slap-on fixes is not my cup of tea, but chronic or latent design deficiencies have gone on before without remedial action until Jaguars, and their public image, have been damaged.

My fear is that the air suspension systems will eventually become a serious issue, particularly now that inceptionX350's are leaving factory warranty. Aftermarket bolt-on shock kits worked fine for XJ40, butsuch anattempt in the future for X350 cars will indeed be a slap-on, and only a crude fix at best.

At least I have gotten a toe hold "inside the loop"for the moment, andI'm hoping this will lead to my better grasp of the issues and a hand in fixing things. That's my job.

 

BTW, the forums in the UK has vast reports of suspension issues in cold weather as well. See http://www.jaguarforum.co.uk/viewforum.php?f=22

 

Thank you for that link, it reinforces three points:

1) That I don't know very much about the system, having never seen a compressor or its location;

2) That a forward engine bay location makes my suggested modifications easier to implement;

3) That this is not an uncommon occurance, and it ain't gonna heal.

The issue of strut leaks is likely to be a separate cause: I have been told that someair leaks are only obviouslypresent in cold soak conditions. But if internal sealing is being degraded or otherwise affected by moisture, perhaps there is linkage to myproposal in that regard.

I asked the Dealership Shop Foreman if he had ever seen signs on moisture in failed air suspension system components, perhaps eveninverting a removed strut and seeing if anything runs out. His response was, "We'll look now".

That's not a knock against him or any dealership personel, it just points out a difference in priorities. Mine are more long term, they have a customer waiting to get back on the road.

 

Thanks for your interest and willingness to help with this problem Andrew. I only acquired my VDP in September of '08 and have not experienced any issues yet.Since I live in Houston, TX that probably explains why. As yet this year, we haven't had an official freeze and since I live fifty miles South of the airport, my home thermometer hasn't even come close. With that said, my car is a first year X350 so I have to wonder if it isn't just a matter of time before I have problems even without the cold weather. Oh well, I have another ten months of J/S warranty so maybe if it is going to break, it will do so before then.

 

Thanks for your input,now it can be said that"I know Jack".

There has been conflicting information posted in various places, but I'm more inclined to believe that the struts are not covered by Select Edition. I have no specific knowledge.

Aside from staying warm in your area, it's nice and arid. Wouldn't it be fun to plot warranty claims on a world map and see where the concentrations appear... perhaps in some areas, this is much ado about nothing.

 

Kudos JTO for your work on this problem!!!!!

 

I've been giving this some thought. I think the system as it is, is probably not too bad. The compressor is a throwaway item about every 40,000 miles it looks like. The other problems sound sporadic. I have the problem with my car and have ordered the compressor and will replace it. I felt that it is the price of cutting edge systems and will just put up with it...no choice anyway.I think the compressors work too hard for their design, the cold stresses them and puts an end to theircompressingand they should have a drier/filter on them. These driers are not expensive and last for years but it is not to be in this car. My brother has a 94 Lincoln with air suspension, the driers for itare $40 and the aftermarketcompressors are $200. They fail pretty fast too, about 30,000 miles for them. The Jag compressors are $900 at the dealer for a rebuilt, not new. It would be nice if an aftermarket supplier would make a better compressor, but the limited salesof the XJ8 probably preclude this happening. It will be interesting if you can find out if there is water in the systems causing problems. I think there probably is, let's hope it's not too much. Thanks for putting it out there.

 

Hi,

Thanks for the post....I wonder, though, if this problem is related to the early ( 2004 ) models and older, asall posts that I have read seem to pertain to 2004 or older models....I just purchased an 'o8 XJR and do live in Chicago where it gets pretty bad during the winter...A friend of mine has on '05 VDP and never ad this problem...just curious...

 

Greetings rusbel,

I don't know the answer to your question, and I hope you are right that some corrective action was taken to limit the faults to '04 and perhaps '05 cars only. The link that jaglover provided cites more histories, but I recall the majority of those cars as being '04.

So if some running production change was made, it would make sense that earlier cars should be retrofitted with these system modifications or upgraded components. One way you can sometimes get a hint of such changes are in cases like oldmots, when you order a component and are supplied with a replacement that has a superceded part number, or is visually different from the original.

 

Well motts, I guess that points out a few differences between you and me, but that's nothing new either.

If our roles were reversed, instead of speculating about the issues I would be doing the following:

Tracking down the rebuilder and inquiring as to whether any upgraded internal components or modifications are found inside this new compressor I bought.

Testing the existing compressor in several different operating environments and recording pressure output vs. time vs. ambient temperature vs. drivetime before test

Removing and dismantling the existing compressor to inspect for evidence of moisture ingress, and to hopefully determine the cause of its reduced pressure output. I would be inclined to tear it down even if that meant eating a core charge, because I'm more interested in finding answers thandismissing them.

Inspecting the connection fittings at the compressor and searching for an off-the-shelf receiver/ drier thatwas most appropriately designed for easy installation. I would select the smallestcapacity drier I could find that wouldbe able to handle the requiredflow rateand pressure: I WANT to see it get plugged up, and therefore verify that moisture is getting into the system when no preventive action is taken. One receiver/ drier I have found so far even has a sight glass, so the condition of the desiccant can be monitored when it changes color.

Installing the rebuilt compressor, without the drier and in its stock configuration, and duplicating all of the tests I made with the original unit for comparison. It would be nice to know if my rebuilt was any better than the unit it is replacing, and also point out whether or not I had diagnosed the cause of low system pressure correctly.

Installing the reciever/ drier and monitoring its effectiveness, or lack thereof. If I can't tell it's doing any good, it will be a long time before I can even guess if it was protecting any or all of the system components.

I don't have an X350, or a rebuilt pump, or warranty return CATS components, or a stack of feild reports and diagnosic results to inspect. All I can do at the moment is to continue "giving this somethought". And "I think the system as it is, is probably not.." ... good enough.

 

I took the liberty of moving BRUTAL'S post to this thread, as I'm trying to keep all of this information grouped together to print at some point:

BRUTAL
Super Member


[align=center][/align]


Posts: 679
Joined: 9/28/2008
Status: online
"actually I was jut talking to a customer today about your thread on air suspension....especially since I put a air pump in his car a couple months ago. We talked about common failures on 04^XJ's air pump is the first to come to mind. I dont know that Jag will ever come out with a big fix for this, I think will probobly come from people like you and forums like this.....Jaguar will probobly redesign either system or pump to address this issue in the upcoming release( I hope)"


Thanks for your input BRUTAL, if you ever have any customer pay compressor or strut cores I can look at, PM me and I'll pay you shipping and handling. Have you encountered any difference in the hardware so far that indicates any of the componenets have been upratedfrom '04 models? As rusbel suggests, that is where most of the problems have appeared so far. I don't know if that is simply an indicator of life expectancy, or whether pieces have been made with greater durabilityinlater Model Year cars.

 

That is correct, not covered.

 

Thanks jahummer, I readfrom a poster on another forumwho states he is employed at a Jaguar Dealer. His service manager reportedly says the struts were covered, but I did not think his info was correct. Thank you for yours.

 

My early build (June 03) 04 XJ8 went through 80,000 miles without any problems with the suspension. Only one data point, I know, but I live in a relatively warm place (northern California, Bay Area) and we only get below freezing a few days a year. This si a good thread. Very interesting to see if it ismostly an early build (meaning 04s) problem as I now drive an 06.