I appreciate your comments, tallbird.

I think you may be right with regards to the shocks being at full pressure. The frustrating thing is that no warning lights accompany the rough ride and its pretty much constant. I'll be trying the relay swap suggested by hlgeorge today; hopefully that'll work.

 

Just tried switching the relays. Still no improvement. Ride is still very harsh. If no warning lights come on, and no codes are being stored, I have no idea what to do. At first I thought maybe I was imagining the rougher ride, but several passengers have noticed it too. I have to drive on the freeway everyday to work and back, and I absolutely dread it now. My 20 year old Series III XJ6 had a smoother ride than this!

 

how about disconnecting the wire to the compressor or the relay, and driving around locally for a while? If the ride softens up some, then it is overpressurizing the system. I don't know what it would take to do this, or how long you would have to drive to depressurize it, but might be worth a try.

TB

 

Unfortunately, I wouldn't know how to disconnect anything. I went out of town for a couple of days, so the car has been sitting. Still no difference in height. When I turn the car on, the front end rises a bit, but the car still feels like crap. Im starting to think that it is overpressurized. Could this be a sensor issue? Any ideas on what could be causing this?

 

In general, the air suspension fault message isn't very alarming. It can just mean that the compressor is taking longer than normal to pressurize the system. Maybe the car just has to get over its humiliation at being dragged *** end first out of the ditch. If you have a real leak in the system, you are likely to get the more serious message and the car will sink down to the stops. If you don't have your manual with you, I'll go get mine and quote the message to you. You should be ready to recognize it. You probably will need a tow at that point. Meanwhile, go ahead and drive it, but keep an eye out for message changes. And you might plot a route home via places where you can get help.

Good luck.

 

I drove my 04 xj8 for one year with "air suspension fault" warning light that would come and go with no noticable problem. Then the left side of the suspension filled itself to capacity. My machinic thinks its a sensor, he is unable to reprogram. the jag dealer whats to replace the suspension for $3500 any thought out there that might save me some $.

 

Agcat, did you read the entire thread ^^ above, and the other couple suspension threads that have been hot topics for several months? Most (99%) of all issues have been addressed in these many posts from some dedicated members.

 

Yes, I have read all the posts and more nothing fits my problem, the common problems are leaks in the system. I think it may be the air pressure relief valve. I also found out that my mechanic had different codes than the dealer. I will post them when I get them.

 

Mine failed for the second time this year over the weekend, this time the front which is now sitting down like a lowrider. On the plus side there is not interference between the tire and fender when it is sitting down so I was able to get home with it. It goes to the shop on Friday when I get back to DFW. This was not a really well designed system--why did they feel they needed to go air suspension even though Jags have always had a good ride/handling balance even on steel springs?

Were the OEM pumps made by Lucas?

 

Supposedly because the body is lighter due to it being made from aluminium:-


From the X350 training guide:

A lighter body requires spring rates that are matched to the body mass and therefore the spring rates are lower.

To the designer this is not a major problem in itself. However, when a vehicle is loaded, the softer spring rate will allow the vehicle body to travel beyond the design intention.

Hence the reason for selecting air suspension as a feature to replace the normal spring arrangement and assist where spring compression would be loaded beyond its natural spring state.

Benefits Summary

Provides better vehicle levelling independent of load Improved ride performance over coil springs for a light weight vehicle.

Vehicle aerodynamic improvements can be achieved using air suspension providing better performance and fuel economy.

The system is fully automatic with no driver required inputs (better life cycle prediction can be'achieved).

Its an electronically controlled system complete with on-board diagnostics.

Vehicle styling and stance is visually enhanced.

The new XJ, of course, has gone back to coil springs on the front

 

Interesting. I had thought it was because Mercedes introduced their own failure prone system on the S-Class and they were trying to keep up.

The only thing that does not make sense about that is that the car, at 3800 pounds is light for its size but it is still no anorexic...

BTW--this time the problem was one of the $1600 shocks.

 

It is likely a shock. If you go to a dealer they may want you to replace both front shocks for $3200 +/- which will be a bit of a shock in and of itself.

I would suggest rereading this thread and using the search function to find out more on suspension failure modes so that you can have an idea of what is going on.

 

LMAO I JUST GOOGLED IT AND YOU ARE RIGHT!

Freaking new XJ has coils bahahaha, that's ridiculous... I mean come on it is proved that air suspension is way better than coils even though they are costly to replace, but coils on XJ? pffft now that is a huge turn off.

 

The fact that they went back to coil springs actually makes the new one more attractive for me--coil springs don't leak. It also means that the write up in the training guide was nicely worded fiction as the new car is quite similar to the X350 underneath the skin and that Tata/Jaguar recognized the warranty cost mayhem they caused.

Regarding the functional benefits of air ride: There were some road testers who preferred the ride/handling balance of the steel sprung X300 to the X350 and there are quite a few luxury cars on coil springs that ride and handle just fine.

 

^ and in addition to jsher's suggestion, you'll also learn of an alternative shock replacement to the dealer shock, at least for the front.

 

Maybe it was because the X300 was a heavier car not being made from aluminum

 

THE NEW XJ rides alot better than the old(X350) and without the air spring, and compressor issues. The compressor should last longer to since it doesnt have to fill large air springs in front. And as pointed out, Ive yet to see metal leak. Thatll give it a much lower duty cycle. And the main reason is to be able to adjust ride height for HIDS. All you do is either raise over lower the rear to keep the front HIDS level. Seems like a big improvement to me

 

I got curious and looked up the comparative weights--found the data on automotive.com:

2000 XJ8--(X300) had a curb weight of 3,938 (SWB)
2004 XJ8--(X350) had a curb weight of 3,801 (SWB)

The curb weight difference is about 5%