Hello.

I am a heavy diesel mechanic from New Zealand who works on cars on my off time. I have been browsing the forum for a few months and have seen the great information the members of this forum have to offer.

I have recently been working on an late 2003 XJR (As far as I can tell a 2004). It's a beautiful car that I really want to get right. The owner is someone who I know. He started having issues around 12 months ago. It had leaking airbag and he got all 4 replaced but it was moving its self up and down/going too hard. He had it in at the local dealer who told him it was a faulty valve block but they could not get one. I have replaced this which seemed to have helped and the error message went away for the initial test drive but came back after turning the car off an on again a couple times. I have since replaced the compressor as I found corrosion in it. After replacing this the car did the same again. It seem to be driving fine to me and the owner. The "Air Suspension Fault" yellow light has started coming on again after approximately 1-2 minutes of driving . It appears to lifting the front of the car up too much (Around 30-40mm high compared to spec at the front end) but has started to settle with more driving. I was wondering if anyone had any ideas on this.

Unfortunately my scan tool cannot read suspension faults this car so this is extremely vague.

Should the car let the airbags down when I manually manipulate the level sensors? (One each corner on this late 2003 car) as is doesn't seem to be doing so if that is expected.

I have tried to manually let some air out of the shocks by very carefully undoing the fitting on top of the front shocks but it did not let any air out/let the shock down (lifted up or on the ground)

Any help is greatly appreciated. I know this is probably useless not having any DTCs but I really want to get this beautiful car right for the owner.

Thanks.

 

Hi.
normal hight front 386mm middle center cap to wheel arch just staight up
Rear 373mm.
15mm + or - is ok to drive . .
it is normal for the system to regulate hight while drivng around when it was to high or low.
if there was a corroded aircompressor in the front left of the car My guess is that it also had humid air in the rest of the system. So nylon hose to the rear , the valve block ,the tank the struts have humid air inside. Rather good you have let some air out of the system by loosening the brass fittings . I suppose you had humid fingers. If it is a brand new compressor you have installed the dessiccant beads should be able to drie the air enough. You csn exchange those beads or take them out of the compressor to drie them in sn oven for an hour and put them back in. As much as a glass full.
All x350 x356 x358 ( some exeption wich are daimler ,vanden plas or armoured cars)
lower a bit when door is opened to get in,
Lower a bit to get out when opening door
Lowering when driven over 100mph over a couple of min in a row by 15mm .( Apperently not on Daimler , vanden plas , not on armoured they have no airsuspension)
if you drive then stop on a place put the car in neutral wait and have a look over the bonnet. It might regulate.

When car is locked wabco cats module behind rear seat is regulating car towards being leveled every half hour.
if you unhook battery after stopping this system is not working. So this is the way to go if you want to find out if any strut is leaking.
mesure initial hight after stopping , unhook battery, check again in 12hours maybe 24.
should stay up thight for at least a week

 

You'll never fix it without a scanner to read the codes. The system is well beyond its design life anyway, and throwing money at guesses will cost more than the car is worth. Also, if you are not aware of it, once the system shows air suspension fault, it simply stops trying. It will not make any effort to level the car until the key is turned off and the car restarted, and then you probably only get a couple of minutes until the next fault display.

I am fervently in favor of abandoning the air suspension system and installing conventional coilovers with steel springs. Many companies make the replacement struts, and installation is not difficult.

ALL automotive air suspension systems have a serious basic design flaw in that they lack a separately serviceable dryer. The dryer is a desiccant chamber in the compressor, and it requires disassembly of the compressor to service, whether you want to replace the beads or simply dry them (if you have reusable desiccant beads.) Once water gets past that and into the system, there is no process for removing it, so valves rust. I replaced my struts with Arnott struts and never looked back. I will never have another vehicle with air suspension as long as I live.

 

Well i love the airsuspension and have 2 currently running
both from 2003 one of the with 228.000 miles comfy and reliable

 

That's fine. What has it cost to keep them that way? What's the average humidity where you are? I'm in Florida, which is muggy sub-tropical. When I first removed my compressor to examine it, the desiccant chamber was actually a water tank.

 

I truly appreciate you wanting to "make it right" for your friend. I think the way to go is remove it. otherwise as was pointed out you'll be throwing money at it for the rest of the cars life. I fought with my airbag system for years and I Do have the scanner. I gave up when I found an Arnott coil- over set for about 1/2 usual price. It Really is an Easy conversion and it comes with a sender for the wabco control unit to turn that D***** light off. I did the whole job in one afternoon. It was probably a really cool thing when it was new and worked, but it didn't age well. If you do a search of the system, even just on this site, you'll find page after page of complaints and questions on many aspects of this system, often too high or to low here or there or that light just won't go out. Save yourself the headaches. And good luck.

 

Look at Miessler automotive
they have new valve block and a lot of other stuff related to our cars and other air suspension systems or brands.
they do send packages like right away from Germany if they have the pieces in stock

 

I have had the same Jag ie late 2003 for 17 years and it has been very very, reliable.
If the owner wants to keep the car it would be worth it for him to buy a scanner but
I am not sure it will show all air suspension faults.
Now that the compresser has been replaced we can forget the possible worn out piston ring
but I would be suspicious about the level sensors.
I think it would pay to inspect them all,look for damage,take them off (easy to do) feel them moving
do they all feel the same? They are just a variable resistor AFAIK also test them electrically.

Very rarely you can have a bad connection on the plug to the brain located behind the back seat.
Would be worth checking that-see this forum for details to remove rear seat
It might be worth also looking for any possible faults on the the pcb also.
I can't explain why there was no effect after disconnecting an air line to a strut !
Cheers
.

 

I have just converted mine to coilovers after endless trouble with the air suspension and I'm super happy...