Interesting Air Suspension Issue
#21
01-18-2023, 04:38 PM
Senior Member
Yeah, it's called the Air Suspension Module, and it's located on the wall behind the rear seat. As for the level it's trying to reach, that's a standard level, although it's lower (for aero) above 105 mph. The system tries to keep all for corners at the same height at all times.
The air Suspension has nothing to do with shift points. As far as I know, shift points are determined entirely be the speed of the car, the engine load (i.e. hard throttle or pretty much coasting,) and whether in Sport or normal mode by the button on the console.
If you want to get rid of headaches from air suspension that doesn't work, get a set of coilovers. It's what I did when I found so much water in my system that I had no hope of recovering any good function from it. The dryer chamber of my compressor was actually a water tank! The desiccant was clumped like cat litter! Finding that meant that water has been pumped throughout my system... into the reservoir and into the shocks' air bags. There is no way to get the water out, or to remediate the corrosion it causes in valves and other structures, so I gave up, went coilovers, and transformed the car from an expensive mistake I was going to regret ever being involved with, to the best and most comfortable car I've ever owned.
There will be people who will tell me I should have persisted, that there's absolutely nothing like a Jag with working air suspension, but at what cost? The car is worth maybe 7 grand on a good day and I'd need at least half of that to get everything actually working, pretty much a complete overhaul of everything: compressor, reservoir, struts, and valve body, along with all the fittings in between all the pieces. I spent less than 1300 on Arnott coilovers and have not had a care about suspension issues since. The car rides better than it ever did while I had air struts on it, it drives great, it's reliable, and I'm loving it! I've never been in a Jag with working air suspension so I can't make a direct comparison to function, but I can certainly make a direct comparison to cost and value!!!
The air Suspension has nothing to do with shift points. As far as I know, shift points are determined entirely be the speed of the car, the engine load (i.e. hard throttle or pretty much coasting,) and whether in Sport or normal mode by the button on the console.
If you want to get rid of headaches from air suspension that doesn't work, get a set of coilovers. It's what I did when I found so much water in my system that I had no hope of recovering any good function from it. The dryer chamber of my compressor was actually a water tank! The desiccant was clumped like cat litter! Finding that meant that water has been pumped throughout my system... into the reservoir and into the shocks' air bags. There is no way to get the water out, or to remediate the corrosion it causes in valves and other structures, so I gave up, went coilovers, and transformed the car from an expensive mistake I was going to regret ever being involved with, to the best and most comfortable car I've ever owned.
There will be people who will tell me I should have persisted, that there's absolutely nothing like a Jag with working air suspension, but at what cost? The car is worth maybe 7 grand on a good day and I'd need at least half of that to get everything actually working, pretty much a complete overhaul of everything: compressor, reservoir, struts, and valve body, along with all the fittings in between all the pieces. I spent less than 1300 on Arnott coilovers and have not had a care about suspension issues since. The car rides better than it ever did while I had air struts on it, it drives great, it's reliable, and I'm loving it! I've never been in a Jag with working air suspension so I can't make a direct comparison to function, but I can certainly make a direct comparison to cost and value!!!
My car only has 46k on it and I'm converting it to Arnott in the Spring. After seeing it sag when cold I know at some point it will cause me a headache that I don't need and its just not worth it. Not worth dealing with aftermarket air springs, compressor, lines, and all the other stuff that comes with it. If OE springs were not $2k+ I'd consider sticking with it, but as you said the car is barely worth $10k on a good day, no way I'm putting $8k of suspension on it.
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eliotb (01-22-2023)
#22
01-19-2023, 12:07 PM
#23
01-21-2023, 09:56 AM
Jag suspension issue
I understand the air suspension is different and not directly tied to the shift points on the transmission. My understanding though is selecting the sport switch also changes the transmission shift points, hence the "sport" setting.
That all aside I have read in some thread that when you do the changeover to coilovers that you need some sort of box to tell the computer not to have air suspension and ride height lights show up on the dash. When you did your changeover or in any of your readings is that anything that you have needed to address? I believe I was just looking at getting some Arnott coilovers and they do include some module specifically for that. They call it a bypass module.
I have looked at other brands and do not see a module included in their description.
That all aside I have read in some thread that when you do the changeover to coilovers that you need some sort of box to tell the computer not to have air suspension and ride height lights show up on the dash. When you did your changeover or in any of your readings is that anything that you have needed to address? I believe I was just looking at getting some Arnott coilovers and they do include some module specifically for that. They call it a bypass module.
I have looked at other brands and do not see a module included in their description.
Yeah, it's called the Air Suspension Module, and it's located on the wall behind the rear seat. As for the level it's trying to reach, that's a standard level, although it's lower (for aero) above 105 mph. The system tries to keep all for corners at the same height at all times.
The air Suspension has nothing to do with shift points. As far as I know, shift points are determined entirely be the speed of the car, the engine load (i.e. hard throttle or pretty much coasting,) and whether in Sport or normal mode by the button on the console.
If you want to get rid of headaches from air suspension that doesn't work, get a set of coilovers. It's what I did when I found so much water in my system that I had no hope of recovering any good function from it. The dryer chamber of my compressor was actually a water tank! The desiccant was clumped like cat litter! Finding that meant that water has been pumped throughout my system... into the reservoir and into the shocks' air bags. There is no way to get the water out, or to remediate the corrosion it causes in valves and other structures, so I gave up, went coilovers, and transformed the car from an expensive mistake I was going to regret ever being involved with, to the best and most comfortable car I've ever owned.
There will be people who will tell me I should have persisted, that there's absolutely nothing like a Jag with working air suspension, but at what cost? The car is worth maybe 7 grand on a good day and I'd need at least half of that to get everything actually working, pretty much a complete overhaul of everything: compressor, reservoir, struts, and valve body, along with all the fittings in between all the pieces. I spent less than 1300 on Arnott coilovers and have not had a care about suspension issues since. The car rides better than it ever did while I had air struts on it, it drives great, it's reliable, and I'm loving it! I've never been in a Jag with working air suspension so I can't make a direct comparison to function, but I can certainly make a direct comparison to cost and value!!!
The air Suspension has nothing to do with shift points. As far as I know, shift points are determined entirely be the speed of the car, the engine load (i.e. hard throttle or pretty much coasting,) and whether in Sport or normal mode by the button on the console.
If you want to get rid of headaches from air suspension that doesn't work, get a set of coilovers. It's what I did when I found so much water in my system that I had no hope of recovering any good function from it. The dryer chamber of my compressor was actually a water tank! The desiccant was clumped like cat litter! Finding that meant that water has been pumped throughout my system... into the reservoir and into the shocks' air bags. There is no way to get the water out, or to remediate the corrosion it causes in valves and other structures, so I gave up, went coilovers, and transformed the car from an expensive mistake I was going to regret ever being involved with, to the best and most comfortable car I've ever owned.
There will be people who will tell me I should have persisted, that there's absolutely nothing like a Jag with working air suspension, but at what cost? The car is worth maybe 7 grand on a good day and I'd need at least half of that to get everything actually working, pretty much a complete overhaul of everything: compressor, reservoir, struts, and valve body, along with all the fittings in between all the pieces. I spent less than 1300 on Arnott coilovers and have not had a care about suspension issues since. The car rides better than it ever did while I had air struts on it, it drives great, it's reliable, and I'm loving it! I've never been in a Jag with working air suspension so I can't make a direct comparison to function, but I can certainly make a direct comparison to cost and value!!!
#24
01-21-2023, 10:29 AM
Arnott includes a piece with their shocks that attaches to the wiring harness at the Air Suspension Module to simulate that CATS system's presence. They do not sell it separately for obvious reasons... I mean, who would by their shocks if they could get cheap Chinese shocks and buy the module separately. I think there's another vendor that has a module but I don't recall who. Without that module you get a permanent yellow light on the dash with a CATS error.
#25
01-22-2023, 03:20 AM
Senior Member
This thread is going AWOL when people start associating transmission shift points with air suspension.
Just the other day a seagull flew past, and then my air suspension went down. Why is that?
More seriously, don't be too fast to diagnose. It takes time to monitor it. For example (4 years now and done nothing), my air suspension has at times gone down overnight, other times never goes down including currently.
Why? Grit in the valve block valves which self-cleared, would be my best guess.
When I first bought my Jag I used to worry myself sick on the air suspension (i.e. going down overnight). Now I'm just used to it and as I say fixed itself. Of course, if it's as bad as getting error messages then that's different.
Just the other day a seagull flew past, and then my air suspension went down. Why is that?
More seriously, don't be too fast to diagnose. It takes time to monitor it. For example (4 years now and done nothing), my air suspension has at times gone down overnight, other times never goes down including currently.
Why? Grit in the valve block valves which self-cleared, would be my best guess.
When I first bought my Jag I used to worry myself sick on the air suspension (i.e. going down overnight). Now I'm just used to it and as I say fixed itself. Of course, if it's as bad as getting error messages then that's different.
#26
01-22-2023, 07:36 AM
Senior Member
This thread is going AWOL when people start associating transmission shift points with air suspension.
Just the other day a seagull flew past, and then my air suspension went down. Why is that?
More seriously, don't be too fast to diagnose. It takes time to monitor it. For example (4 years now and done nothing), my air suspension has at times gone down overnight, other times never goes down including currently.
Why? Grit in the valve block valves which self-cleared, would be my best guess.
When I first bought my Jag I used to worry myself sick on the air suspension (i.e. going down overnight). Now I'm just used to it and as I say fixed itself. Of course, if it's as bad as getting error messages then that's different.
Just the other day a seagull flew past, and then my air suspension went down. Why is that?
More seriously, don't be too fast to diagnose. It takes time to monitor it. For example (4 years now and done nothing), my air suspension has at times gone down overnight, other times never goes down including currently.
Why? Grit in the valve block valves which self-cleared, would be my best guess.
When I first bought my Jag I used to worry myself sick on the air suspension (i.e. going down overnight). Now I'm just used to it and as I say fixed itself. Of course, if it's as bad as getting error messages then that's different.
However, at some point it will go wrong then you'll need to repair it or make a decision quickly. If its not a car you depend on every day not a huge deal, but if its a driver (which mine currently is), its not exactly somthing that can be fixed in an hour or two so its best to be prepared.
#28
02-11-2023, 01:09 PM
Small update! I finally got some time to jack up the back end and have a good look at the air lines up there. Everything has been working fine, except for the car dropping on the front, since I last posted. Well, even though I just had the rear subframe off, and all the air lines looked good, I realized the lines actually run up over/under some stuff that would have been hard to see even with the subframe off unless I was specifically looking. SO, I had a good look up in there where they lines run up into the trunk, and guess what, I found an old repair in one of the front air lines! I reached up in there and as soon as I touched it, I could hear air coming out. Guess when I was in there replacing the subframe I moved the lines around and that jarred something in the old repair (not done properly also). Got some proper air line repair parts on the way, so, hopefully this does it!
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Big Koshka (02-12-2023)
#29
02-11-2023, 03:39 PM
Senior Member
Small update! I finally got some time to jack up the back end and have a good look at the air lines up there. Everything has been working fine, except for the car dropping on the front, since I last posted. Well, even though I just had the rear subframe off, and all the air lines looked good, I realized the lines actually run up over/under some stuff that would have been hard to see even with the subframe off unless I was specifically looking. SO, I had a good look up in there where they lines run up into the trunk, and guess what, I found an old repair in one of the front air lines! I reached up in there and as soon as I touched it, I could hear air coming out. Guess when I was in there replacing the subframe I moved the lines around and that jarred something in the old repair (not done properly also). Got some proper air line repair parts on the way, so, hopefully this does it!
#30
02-12-2023, 11:45 AM
Senior Member
Small update! I finally got some time to jack up the back end and have a good look at the air lines up there. Everything has been working fine, except for the car dropping on the front, since I last posted. Well, even though I just had the rear subframe off, and all the air lines looked good, I realized the lines actually run up over/under some stuff that would have been hard to see even with the subframe off unless I was specifically looking. SO, I had a good look up in there where they lines run up into the trunk, and guess what, I found an old repair in one of the front air lines! I reached up in there and as soon as I touched it, I could hear air coming out. Guess when I was in there replacing the subframe I moved the lines around and that jarred something in the old repair (not done properly also). Got some proper air line repair parts on the way, so, hopefully this does it!
Enjoy your Jag and CATS for years to come!
#31
02-13-2023, 06:21 PM
#32
02-17-2023, 03:46 PM
Final Update: Problem solved!
I wanted to wait a few days to make sure it was all good, and it is. I cut out the old repair on Tuesday, aired the car up and when I went to go to work on Wednesday, the car was still up! Drove it all week and hasn't dropped a mm. I like simple solutions. Even though the old repair wasn't really done properly, I guess I can't be too hard on it since it did last at least 7-8 years or more.
I wanted to wait a few days to make sure it was all good, and it is. I cut out the old repair on Tuesday, aired the car up and when I went to go to work on Wednesday, the car was still up! Drove it all week and hasn't dropped a mm. I like simple solutions. Even though the old repair wasn't really done properly, I guess I can't be too hard on it since it did last at least 7-8 years or more.
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87LC2 (02-17-2023)
#33
02-17-2023, 03:58 PM
Senior Member
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WinterJag (02-17-2023)
#34
02-17-2023, 05:25 PM
#35
02-17-2023, 07:21 PM
Senior Member
My theory, and it's completely unproven or often proven in the opposite, is that if the air suspension needed changing after (2023-2004=19yrs, or in my case 15yrs), then a new Air Suspension should last until (2023+19=2042). What's wrong with my maths or logic?
Where the heck did you get a new valve block for that price? I have always suspected that the Valve Block gets less blame than it deserves.
Folks, the problem with this forum is that you only ever hear horror stories. And yet, there's at least 3 X350's that I know of, out of a production run of 83,000, which still have Air Suspension!
(I did buy a Bagpiping Andy kit, but that's in the boot along with the coolant...jump starter...and all the other necessary emergency gear)(as though I'm gonna fix the air suspension on the roadside lol)
Where the heck did you get a new valve block for that price? I have always suspected that the Valve Block gets less blame than it deserves.
Folks, the problem with this forum is that you only ever hear horror stories. And yet, there's at least 3 X350's that I know of, out of a production run of 83,000, which still have Air Suspension!
(I did buy a Bagpiping Andy kit, but that's in the boot along with the coolant...jump starter...and all the other necessary emergency gear)(as though I'm gonna fix the air suspension on the roadside lol)
Last edited by ChrisMills; 02-17-2023 at 07:40 PM.
#36
02-18-2023, 02:30 PM
Got my valve block off ebay. It was aftermarket, but there are tones of them on there in that $70-90 range. They are all the same even with different prices. I really don't think this air suspension deserves all the negative press. Like you, my thoughts are after almost 20 years and 225K miles, it doesn't owe me anything, and a refresh should last the rest of the life of the car. It's going to be a third/fourth car soon (looking at getting myself a XJS and wife kinda wants an F-type in the near future) so should last the rest of it's life in my fleet. I think because these cars aren't worth much, it's the sticker shock of needing to sink like $2k into a $4-5K car, more if you don't DIY. These were expensive cars in their day so it costs to keep them up. For me, spending like $500-$1000 a year on average to keep everything tip top is way cheaper than getting another car. In reality, through my time of owing this car, I would say my average yearly maintenance costs are around $500. I've had years with nothing and years with like $2K.
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