What is a kit for the dryer, what dryer are you talking about? Is it in the compressor ?

 

The air dryer is part of the air compressor assembly. It's a cylinder packed with molecular sieve desiccant beads. See the photos at the links I referenced in post #34.

Cheers,

Don

 

The CATS system controls the adaptive damping rates of the shock absorbers, so there can be a fault with the CATS system is while your air suspension is operating properly. For a summary of CATS operation, see this post:

Air Suspension & ECATS System Summary: Components & Operation

Cheers,

Don

 

I know it's been awhile but I wanted to add a bit more. I recently had the reservoir plausibility fault again. I wanted to let everyone know it turned out to be the valve block. I believe specifically the o ring seals in the brass fittings. The hoses would slide in and out slightly probably leaking just enough to set the code every 3 or 4 outings. I am not absolutely sure the o rings were the problem. I replaced the entire valve block with a new one from miessler automotive off ebay. The seller name is air-suspension-shop-eu Price was $280 with vat tax added in already. Ask them to take 19% off if you don't live in the eu. They will. Also ask for an extra brass fitting for the hose that goes into the air tank. It matters. When you change the brass fittings be sure to note the direction of the small c ring that goes over the hose. Set that ring slightly above the indentation made by the old one. The hose will go slightly further into the block but you get a clean seal. The new block is different than the old 1 and they supply a metal mounting plate. It will fit but there is no hole for the rod for the spare tire mount to come through. I wound up making my own plastic mount for the valve block. My suspension worked good before the fault( because every other component had been replaced). It works superbly now. The compressor cycles more regularly than ever and less. I also bought the lap top with the Jaguar diagnostic tools and set the ride height 10 mm lower (for looks). These suspensions require a ridiculous amount of maintenance but with good aftermarket parts they do work well. Hopes this helps somebody.

 

Hi All, sorry to jump on this thread but there appears to be alot of knowledge on it ,especially Don who has treid to help me in the past.
I have been plagued with air suspension issues for a very long time and quite frankly I dont know why I still own the car. But its a great motor. The ride on my jag is terrible I compare it to driving over a cattle grid most of the time ,I feel every bump and Im convinced that over certian bumps on the motorway the rear wheels actually leave the surface.Its even worse when I go over speed bumps. I do not get any air suspension warnings.. Ive had the car numerous times to an Indy jag garage,who are excellent I may add and there isnt any fault codes stored in the system. The car doesnt lose height when parked ,it rises when I start and self levels when I stop .
Im at a bit of a loss. The car has done nealry 160000 miles and is still on its original compresor. I am thinking of replacing it just to see if anything changes.
If anyone has experianced this or has any ideas on a fix it would be greatly appreciated.
Thanks
Steve

 

Hi Steve,

From your description, I wonder if the problem is not your air suspension, per se, but that either the shock absorbers/dampers are worn out, your suspension bushings are worn out, or both.

At 160,000 miles it is unlikely that your shock absorbers retain their original damping performance, and many cars with half your mileage have required replacement of at least some of the suspension bushings, especially the lower shock bushings, lower control arm bushings, and the entire upper control arm/ball joint assemblies. Have you had those components inspected?

Cheers,

Don

 

Hi Don,, Firstly thanks for your reply.
The car has sailed through its last four Mots. In fact the last one a couple of months ago the mechanic said to me "Its a pleasure to MoT such a well maintained and looked after car".
I would hope either the Mot place(National Tyres) or my Indy would have noticed any worn suspension components, but you never know. I shall ensure they get checked.

Thanks again Don

Steve

 

Hi Steve,

The upper control arm bushings and lower damper bushings are virtually impossible to evaluate without removing the air spring/dampers, but the dampers themselves can be tested by the traditional method of pressing down on the car and quickly releasing to see how the dampers rebound. You just have to be really careful where and how you press on an aluminum-bodied car.

Cheers,

Don

 

Hi Steve,
I replaced all of the control arms on my 04 XJ8. It made a huge difference in ride and handling. Did it at about 115,000 miles. They were very worn and all of the rubber around them was gone. Have read Jag used biodegradable rubber to be eco friendly. Replaced rear tie rods too. It would be hard to believe at your mileage they aren't all worn out. That being said you might want to recalibrate the air suspension ride height before you spend any real money. I lowered my ride height for looks and was very proud of it. After about 2 weeks of being bounced around I changed it back to factory and it is night and day difference. It was an awful ride just having it lowered 10 millimeters. Yours could be out of calibration and this would not show any fault.

 

 

Don I have had this 2008 xj8 for about 6 months with no issues. This is my 4th xj8. As soon as the cold weather hit (25f) the air suspension fault came on. when the temperature dropped to 15f the front end dropped. First thing I did was rebuild the compressor (secnond car I've done) Air suspension fault still came on. I watched live data while driving home tonight. Rear shock position displayed -2 to -5 the whole time. Front shock position was around -20 to -40 for about 10 minutes. Compressor came on frequently but never ran more than 120 seconds or so. I saw no correlation between the front shock positions and whether the compressor was on or off. About 20 minutes into my drive the front shock position read -60 to-66 and the vehicle too low light came on. I slowed and continued to drive but the compressor did not come back on. I pulled into a parking lot and turned the car off, pulled the key, opened the door. Started the car and the compressor came on and the front position raised to about -20 then the compressor stopped. Went through shut down again and restarted and the front shocks raised to -5 position and the compressor turned off. When replacing the compressor ring I did a soap bubble test on all forward tubing. Found very small bubble leak on both front shocks. If this leak is really the problem why did the compressor not come on when the front end dropped? sorry for long post but it was quite interesting to read the live data on my analyzer while I drove home. Forgot to mention that the error code I have been getting throughout this 2302 leveling plausibilty
thanks in advance
Steve

 

Hi Steve,

The reason the compressor operation does not directly correspond with the front ride height is that the system uses the pressure in the reservoir to charge the air springs, and only when the pressure sensor at the valve block indicates low reservoir pressure is the compressor triggered to run (the Air Suspension / ECATS section of the Dealer Training Manual that I linked to in my thread on air suspension components and operation explains all this).

From what we've been able to determine based on member reports, the most common cause of an air spring leaking only in cold temperatures is a leak in the top seal of one or both front air springs. The top seal is a large rubber molding that seals the top of the air spring to the upper mount components. So far there are no known easily-achieved DIY methods for repairing the top seal, although I suspect it might be possible to do so with an appropriate sealant or epoxy that could withstand the relatively high pressures generated within the air springs when traversing bumps.

The most reliable known means of correcting this issue is to replace both front air spring/shock absorber units, either with OE Bilsteins or units from one of the aftermarket brands like Arnott Industries or Suncore. Many owners have opted to convert all four air springs to conventional coil-over units, but I personally prefer the air suspension.

Cheers,

Don

 

Don - Thank you for your quick response. 13f this morning and live data was pretty much the same except that the rear shock position were positive 12 - 15. As I drove the compressor would would cycle on but turn off before having any impact on the front position. Is it ok to drive with low vehicle while I source these new shocks? Also, do you know what the unit of measurement this position indicator is? I will review the training manual you have posted.

Thanks again for you support

Steve

 

Don- sorry to ask again, but do I have to replace air strut with same ride as original? I have no idea whether I have sport mode or comfort mode but would prefer comfort mode for replacement. Is there a way to identify what my current OEM is?

thanks again

Steve

 

Hi Steve,

I had to scroll back to your earlier post to be reminded of your car details - it's a good idea to go to your User CP and edit your signature to add the year, model and engine of your car so others don't have to go hunting for that information.

Since you have an XJ8L and not an XJR, you almost certainly have the Comfort air spring/shock absorber units. The definitive way to tell is to look for a Green dot (Comfort) or Red dot (Sport/Firm) affixed to the outer body of the unit, usually high near the top and often facing inward toward the wheel well where it is nearly impossible to see. You can try to find it with an inspection mirror or bore scope but the Sport/Firm units were fitted primarily to the supercharged cars, so you almost certainly have Comfort shocks. The Bilstein B4 available from Rock Auto as part number 44069483 are an excellent OE solution, but the Arnotts, Suncores, SKPs and A-1 Cardone units are more affordable. Of these, I only have experience with the Arnotts, and they are very good, but like the other non-Bilstein units, they do not support ECATS functionality, so you'll lose the adaptive damping (if that is important to you).

Cheers,

Don

 

For anyone interested: More scanner live data to report. Took the car for a test drive at lunch today (20f) and the front end was bottomed out. Upon start up, the compressor cycled on properly and lifted the front end quite quickly - no suspension fault appeared, Low level light went out. Drove the car for over 1/2 hour and read the following: Exhaust valve closed the whole time. All four strut positions +5-6. (have never seen the front end in positive territory since the cold hit) Pressure sensor ranged 3-8 bar, 5.10V. For most of the ride the compressor run time seemed normal and cycled off at around 8 bar. L&R front solenoid dampers "open" when leveling was "on" Toward the end of the 1/2 hour test drive the front end started to lower, finally hitting around -20. One reading of the pressure sensor read 12 bar - then back to 7 bar. As I pulled into the parking lot the suspension fault came on. Car has been parked for about 45 minutes and is at the same height as when parked. For a while there I thought perhaps the problem was resolved with the compressor rebuild thinking the new piston ring had to "break-in. Still performed better than before the rebuild but still got the fault. Don't mind spending the money on the new struts but I just seen a lot of posts where that did not stop faults.

thanks,
Steve

 

Don - thanks. Had not seen this post before my last post but I have fixed my signature. thanks for the tip

Steve

 

More data for anyone interested: Drove home yesterday evening with temp at 21f. Front had not dropped from the lunch test drive. Front position was at -5. Air compressor kicked on and front move up slightly. Drove all the home plus 1 stop total time 40 minutes. Front postion remained around -5, gradually dropping to -30 or so when the compressor would cycle on. Pressure sensor remained around 7-8 bar and car drove great the whole time with no suspension fault. First time I have not had a suspension error at these low temperatures since this all began last week.

This morning with a heat wave of 34f front stayed up all night and all driving today all strut positions positive +5 - 7. Compressor did not cycle on during drive and pressure sensor held between 8 & 12. Since I was not aware of any issues before the cold spell hit I never looked at any live data before last week when problems started.

thanks,
Steve

 

Hi Steve,

I forgot to answer your earlier question about the ride height numbers. I don't recall what system you are using to view Live Data, but the numbers probably indicate the distance the ride height varies above or below the calibrated setting, probably in millimeters. For more information on ride height calibration, see Cam's post here:

How to Lower Your X350

Cheers,

Don

 

So I have replaced both front air shocks with new Bilstein shocks. Car so far does not drop but we haven't had any single digit cold for a true test. Thought all was good until 3 days after replacing I got a code never seen before in addition to 2303. Got code C1429 and C1424. Open circuit. Anyone know what might cause this? As a reminder I have already rebuilt the compressor piston ring. Live data looks good which I am reading with a Foxwell NT510 that I bought on ebay for $150.

Thanks

Steve