Air suspension... Almost 100% fixed er... right! Suuuure it is!
#1
10-11-2014, 05:01 PM
Air suspension... Almost 100% fixed er... right! Suuuure it is!
One of my first adventures with the new XJ was to see what I could do about the loud suspension compressor. That thing was LOUD! I figured either the piston ring was worn badly or the pump was poorly mounted in the little "mini-suspension" that attaches the pump to the car. How Ironic that the Air Suspension "Heart" is mounted in a conventional spring and rubber bushing suspension itself. That or both things were causing all the very "Un-Jaguar-Like" ruckus.
Anyway, I figured if I was goint to pull the pump out for inspection I should go ahead and get the BagpipingAndy new PTFE Piston ring and Dust seal kit. I noted that several companies have outright copied his kit and design (well, it's Wabco's design, but you know what I mean) and are selling it much cheaper ($23 plus free shipping from UK) vs. 41 + $6 shipping from Andy.
Screw THEM and the stolen horse they rode in on. Not only was Andy's kit the original, he was the guy with the smarts to figure this thing out, and with a US distributor, I had it in my hands in 2 days, not the 8 days + promised by the copycat counterfeit BS companies. I urge anyone getting the kit to buy from the originator. I can't say what quality issues may exist from these rip-off artists, but I can attest to the quality of the parts I got from Andy's distributor. PERFECT. How do you improve on that.
After re-assembly that left front corner was sitting on the bump stop alright. Hell, the tire was almost touching the wheel lip! Looked like the 88 XJ-S that my brother loaned me for a while! Soon as the car was started she pumped up in about 15-20 seconds, and QUIETLY (Hooray!) I can feel some vibration still in the steering column, but the loud drone that was noticeable over everything else was gone. Still not sure I have it suspended perfectly, as there is some "space" above the rubber bushing/grommet on the long shafts that are threaded at the ends to hold the pump. Ther's no metal to metal, but it doesn't look quite perfect. Perhaps I didn't seat the springs all the way into the rubber grommets. I will have to look at it again sometime..
More troublesome is I got my first "Air Suspension Fault" AFTER doing this work. There were no faults before, just a lod pump calling for attention. I drove the car a bit after the work was done with no issues, but the next day I drove off to see this error display. The only thing I can think of is that I introduced a minor leak when I reassembled everything. There is only the air inlet hose (Black rubber hose with spring clip that attached to the white "filter/Dryer?" and the small gauge black plastic hose that attaches to the pump. Also you have the hose that runs along the pump and attaches with the push to release clamps, but I checked everything pretty well and thought I had a nice, tight but not over torqued connection on the black plastic output hose.
Anyone have similar issues or at least a "likely" place to start checking? Could the fault be electronic from either power connector not being solid?
Sigh... Figures I get rewarded for my good efforts with an error that I was doing preventative maintenance to avoid! All suggestions/info/thoughts are greatly appreciated. ALSO: Trying to figure out how to determine "Normal" operation in a leak free/fault free system. Should I still expect the pump to run intermittently? I will hear it run for 5-10 seconds a single time during a trip, and maybe 20-25 seconds once every few days. I can literally go days without it running, then get a couple of runs in ine day, but never over 30 seconds. Would a bullet-proof, leak free system require ANY run time at all? If I do have some level of leak/pressure loss, is it within spec? What does the community say?
Anyway, I figured if I was goint to pull the pump out for inspection I should go ahead and get the BagpipingAndy new PTFE Piston ring and Dust seal kit. I noted that several companies have outright copied his kit and design (well, it's Wabco's design, but you know what I mean) and are selling it much cheaper ($23 plus free shipping from UK) vs. 41 + $6 shipping from Andy.
Screw THEM and the stolen horse they rode in on. Not only was Andy's kit the original, he was the guy with the smarts to figure this thing out, and with a US distributor, I had it in my hands in 2 days, not the 8 days + promised by the copycat counterfeit BS companies. I urge anyone getting the kit to buy from the originator. I can't say what quality issues may exist from these rip-off artists, but I can attest to the quality of the parts I got from Andy's distributor. PERFECT. How do you improve on that.
After re-assembly that left front corner was sitting on the bump stop alright. Hell, the tire was almost touching the wheel lip! Looked like the 88 XJ-S that my brother loaned me for a while! Soon as the car was started she pumped up in about 15-20 seconds, and QUIETLY (Hooray!) I can feel some vibration still in the steering column, but the loud drone that was noticeable over everything else was gone. Still not sure I have it suspended perfectly, as there is some "space" above the rubber bushing/grommet on the long shafts that are threaded at the ends to hold the pump. Ther's no metal to metal, but it doesn't look quite perfect. Perhaps I didn't seat the springs all the way into the rubber grommets. I will have to look at it again sometime..
More troublesome is I got my first "Air Suspension Fault" AFTER doing this work. There were no faults before, just a lod pump calling for attention. I drove the car a bit after the work was done with no issues, but the next day I drove off to see this error display. The only thing I can think of is that I introduced a minor leak when I reassembled everything. There is only the air inlet hose (Black rubber hose with spring clip that attached to the white "filter/Dryer?" and the small gauge black plastic hose that attaches to the pump. Also you have the hose that runs along the pump and attaches with the push to release clamps, but I checked everything pretty well and thought I had a nice, tight but not over torqued connection on the black plastic output hose.
Anyone have similar issues or at least a "likely" place to start checking? Could the fault be electronic from either power connector not being solid?
Sigh... Figures I get rewarded for my good efforts with an error that I was doing preventative maintenance to avoid! All suggestions/info/thoughts are greatly appreciated. ALSO: Trying to figure out how to determine "Normal" operation in a leak free/fault free system. Should I still expect the pump to run intermittently? I will hear it run for 5-10 seconds a single time during a trip, and maybe 20-25 seconds once every few days. I can literally go days without it running, then get a couple of runs in ine day, but never over 30 seconds. Would a bullet-proof, leak free system require ANY run time at all? If I do have some level of leak/pressure loss, is it within spec? What does the community say?
#2
10-11-2014, 05:10 PM
Veteran Member
I've been reading up lately on the normal operation of the suspension and the pump should run every time you drive it. What it does is adjust the suspension with the reservoir, then once your speed is over approx. 20 mph the pump runs to replenish the reservoir. Mine runs for 15-30 seconds every trip.
Will be interested to hear if you find a solution to the vibration. My pump has never made any noise, but I can tell it's running from a slight vibration in the wheel and pedals. Have not looked myself to see if Jag sells the mounting bushings and springs.
Not sure what would have set off your ASF message. Hate to jump right to it, but maybe disconnecting the battery is in order to reset things? If it pumps up with no problems it could be a faulty height sensor or something innocuous (as opposed to any air leaks or excessive pump run times).
As far as I know, the only pressure tube is the small one connected to the side of the pump body. I think all the other larger tubes on the pump are intake and exhaust tubes, they should have no effect on system leakage.
-Michael
Will be interested to hear if you find a solution to the vibration. My pump has never made any noise, but I can tell it's running from a slight vibration in the wheel and pedals. Have not looked myself to see if Jag sells the mounting bushings and springs.
Not sure what would have set off your ASF message. Hate to jump right to it, but maybe disconnecting the battery is in order to reset things? If it pumps up with no problems it could be a faulty height sensor or something innocuous (as opposed to any air leaks or excessive pump run times).
As far as I know, the only pressure tube is the small one connected to the side of the pump body. I think all the other larger tubes on the pump are intake and exhaust tubes, they should have no effect on system leakage.
-Michael
Perhaps I didn't seat the springs all the way into the rubber grommets. I will have to look at it again sometime..
More troublesome is I got my first "Air Suspension Fault" AFTER doing this work. There were no faults before, just a lod pump calling for attention. I drove the car a bit after the work was done with no issues, but the next day I drove off to see this error display. The only thing I can think of is that I introduced a minor leak when I reassembled everything. There is only the air inlet hose (Black rubber hose with spring clip that attached to the white "filter/Dryer?" and the small gauge black plastic hose that attaches to the pump. Also you have the hose that runs along the pump and attaches with the push to release clamps, but I checked everything pretty well and thought I had a nice, tight but not over torqued connection on the black plastic output hose.
Anyone have similar issues or at least a "likely" place to start checking? Could the fault be electronic from either power connector not being solid?
Sigh... Figures I get rewarded for my good efforts with an error that I was doing preventative maintenance to avoid! All suggestions/info/thoughts are greatly appreciated. ALSO: Trying to figure out how to determine "Normal" operation in a leak free/fault free system. Should I still expect the pump to run intermittently? I will hear it run for 5-10 seconds a single time during a trip, and maybe 20-25 seconds once every few days. I can literally go days without it running, then get a couple of runs in ine day, but never over 30 seconds. Would a bullet-proof, leak free system require ANY run time at all? If I do have some level of leak/pressure loss, is it within spec? What does the community say?
More troublesome is I got my first "Air Suspension Fault" AFTER doing this work. There were no faults before, just a lod pump calling for attention. I drove the car a bit after the work was done with no issues, but the next day I drove off to see this error display. The only thing I can think of is that I introduced a minor leak when I reassembled everything. There is only the air inlet hose (Black rubber hose with spring clip that attached to the white "filter/Dryer?" and the small gauge black plastic hose that attaches to the pump. Also you have the hose that runs along the pump and attaches with the push to release clamps, but I checked everything pretty well and thought I had a nice, tight but not over torqued connection on the black plastic output hose.
Anyone have similar issues or at least a "likely" place to start checking? Could the fault be electronic from either power connector not being solid?
Sigh... Figures I get rewarded for my good efforts with an error that I was doing preventative maintenance to avoid! All suggestions/info/thoughts are greatly appreciated. ALSO: Trying to figure out how to determine "Normal" operation in a leak free/fault free system. Should I still expect the pump to run intermittently? I will hear it run for 5-10 seconds a single time during a trip, and maybe 20-25 seconds once every few days. I can literally go days without it running, then get a couple of runs in ine day, but never over 30 seconds. Would a bullet-proof, leak free system require ANY run time at all? If I do have some level of leak/pressure loss, is it within spec? What does the community say?
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Blairware (10-11-2014)
#3
10-11-2014, 06:16 PM
#5
10-12-2014, 09:46 PM
Thanks all - appreciate any thought you guys are putting into this. I think the punp is working well since the rebuild as a) It's quiet, and b) It pumped up the front corner that was low from having the pump removed in about 10 -15 seconds. I just have no idea what I could have changed or affected that has now cause 2 occurrences of "Air Suspension Fault"
The car sits high. The pump runs quiet, and not often. I seem to have the behavior I have read in a few cases. Start up and drive off to observe "Air Suspension Fault" - Park for an hour or more, fault clear. Yet if I don't park for a while the error stays, once tripped until a rest period or new "cycle" can begin? Does any of that tell us anything?
One theory out there was the "rate" of pumping, as in PSI, if too low, and takes over some time threshold to top the reservoir will trip this alert. If so, I don't know what a rest period or a time out with ignition off for an hour or two has to do with clearing the condition. All I know is I seem to have a fully functional system, that now throws errors, when before it didn't but was loud enough to cause concern. I would love to have a pressure gauge on either the pump, or better, on the reservoir. That would provide a world of helpful data. I saw a post where someone did this. Any idea how that would be accomplished?
Thanks again to everyone who chimed in with ideas and thoughts. This air suspension is not a horrible thing, in fact it seems reasonably well designed, but can become a nightmare if it starts failing all at once. THAT is exactly what I am hoping to circumvent.
The car sits high. The pump runs quiet, and not often. I seem to have the behavior I have read in a few cases. Start up and drive off to observe "Air Suspension Fault" - Park for an hour or more, fault clear. Yet if I don't park for a while the error stays, once tripped until a rest period or new "cycle" can begin? Does any of that tell us anything?
One theory out there was the "rate" of pumping, as in PSI, if too low, and takes over some time threshold to top the reservoir will trip this alert. If so, I don't know what a rest period or a time out with ignition off for an hour or two has to do with clearing the condition. All I know is I seem to have a fully functional system, that now throws errors, when before it didn't but was loud enough to cause concern. I would love to have a pressure gauge on either the pump, or better, on the reservoir. That would provide a world of helpful data. I saw a post where someone did this. Any idea how that would be accomplished?
Thanks again to everyone who chimed in with ideas and thoughts. This air suspension is not a horrible thing, in fact it seems reasonably well designed, but can become a nightmare if it starts failing all at once. THAT is exactly what I am hoping to circumvent.
Last edited by Don B; 10-14-2014 at 04:01 PM.
#7
10-13-2014, 05:24 AM
Veteran Member
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#8
10-14-2014, 03:18 PM
Yes - the car remains level and does not sit low in any way. The message seems to be without merit, however the fact remains that I never had a fault before I removed, rebuilt and replaced the pump so logic dictates that I changed some parameter or left something in a less desirable state than before the work.
Interestingly, BagPipingAndy has been trying to help, and that adds even more value to his kit than the newcomer companies selling the exact same components but doing so cheaper (Cavat emptor!)
One item he asked me to check is the ground strap (Earth to the Brits) behind the headlight. Well, last night I took the 2 attached wires off, and cleaned the stud, filed the two clips and put them back on. I barely began to snug down the nut when the stud sheared right off. I am strong, but I am certainly not ham fisted, and I swear I could not have had more than 10-15 ft lbs of torque on that nut. Ahh well, it doesn't really matter now does it?. I found and alternate place on the firewall, filed the paint off around it and put a nut & bolt through and re-attached the 2 ground straps. Funny..I could be dead wrong, BUT... It feels like the original stud and nut were possibly aluminum (Aluminium for the Brits!) a) Is that possible? and b) Why on earth (pun sort of intended) would Jaguar make a GROUNDING device out of aluminum when it is known to not be nearly as conductive as steel? I say this because they both feel very light weight. in other words... like ALUMINUM.... which could make sense. Can you weld or attach steel to an aluminum body? I don't have the metallurgy skills or knowledge to answer that one!
While it is WAY too soon to draw a conclusion, I will say I have a full day of no faults yet. That is too short of a time span to even HOPE it's gone, but I AM hoping nonetheless. Thanks Guys, really. I am looking into getting codes read if there is another occurance.
Best regards,
John Blair
Interestingly, BagPipingAndy has been trying to help, and that adds even more value to his kit than the newcomer companies selling the exact same components but doing so cheaper (Cavat emptor!)
One item he asked me to check is the ground strap (Earth to the Brits) behind the headlight. Well, last night I took the 2 attached wires off, and cleaned the stud, filed the two clips and put them back on. I barely began to snug down the nut when the stud sheared right off. I am strong, but I am certainly not ham fisted, and I swear I could not have had more than 10-15 ft lbs of torque on that nut. Ahh well, it doesn't really matter now does it?. I found and alternate place on the firewall, filed the paint off around it and put a nut & bolt through and re-attached the 2 ground straps. Funny..I could be dead wrong, BUT... It feels like the original stud and nut were possibly aluminum (Aluminium for the Brits!) a) Is that possible? and b) Why on earth (pun sort of intended) would Jaguar make a GROUNDING device out of aluminum when it is known to not be nearly as conductive as steel? I say this because they both feel very light weight. in other words... like ALUMINUM.... which could make sense. Can you weld or attach steel to an aluminum body? I don't have the metallurgy skills or knowledge to answer that one!
While it is WAY too soon to draw a conclusion, I will say I have a full day of no faults yet. That is too short of a time span to even HOPE it's gone, but I AM hoping nonetheless. Thanks Guys, really. I am looking into getting codes read if there is another occurance.
Best regards,
John Blair
#9
10-14-2014, 03:30 PM
#10
10-14-2014, 04:04 PM
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The reason the studs are aluminium is because steel and aluminium can
corrrode because of the electrolytic effect of two dissimilar metals.
I just knew what you were going to write after 'barely snug down the
nut' because I have read it on this forum so many times!
About four years ago I had an amber light and an ASF message.
I stripped down the compressor, gave the seal 'a good looking at',
streched the seal gently and rebuilt the compressor.(seals were not available
then and I was considering having one made)
Result-the light and message have not reappeared in four years!
corrrode because of the electrolytic effect of two dissimilar metals.
I just knew what you were going to write after 'barely snug down the
nut' because I have read it on this forum so many times!
About four years ago I had an amber light and an ASF message.
I stripped down the compressor, gave the seal 'a good looking at',
streched the seal gently and rebuilt the compressor.(seals were not available
then and I was considering having one made)
Result-the light and message have not reappeared in four years!
Last edited by meirion1; 10-14-2014 at 04:07 PM.
#11
10-14-2014, 04:18 PM
Join Date: Feb 2014
Location: Crossroads of America
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Funny..I could be dead wrong, BUT... It feels like the original stud and nut were possibly aluminum (Aluminium for the Brits!) a) Is that possible? and b) Why on earth (pun sort of intended) would Jaguar make a GROUNDING device out of aluminum when it is known to not be nearly as conductive as steel?
Hi John,
I've been out of town so I'm just catching up on your adventures, so I may reply to some of your questions out of order.
First of all, yes, the ground studs and the large nuts are aluminum or aluminum alloy. The reason they are not steel is to prevent the galvanic corrosion that would result from the contact between the two different metals. Aluminum is actually an excellent conductor, nearly four times more conductive than iron, the principal component in steel. See the chart at the link below:
http://www.mains-cables-r-us.co.uk/b...nductivity.jpg
You are not the first to break a ground stud. There are many reports on the forum. I couldn't find the torque specification in the Workshop Manual, but I did find it in the '04 XJ New Model Introduction Dealer Training Manual, on page 3-11. It's just 9 Nm / 6.5 ft-lbs! I'm working on a post about the ground points and will provide the full information there.
Regarding your new ASF after your pump rebuild, a few possibilities come to mind:
1. Is it possible that you accidentally installed the new piston ring upside down, so the the lap joint in the ring is allowing some air leakage through the gap?
2. Is it possible that either the brass "olive" on the outlet air hose, or the O-ring seal on its threaded brass fitting, is not seated properly and is allowing a leak? You could moisten the fitting with soapy water and watch for any bubbles when the compressor runs or you know the system is pressurized.
3. Is it possible that when you cleaned the cylinder head some gunk or debris may have propped open the check valve so it is not properly seating?
4. If your exhaust valve had some internal corrosion, perhaps moving the compressor around loosened some corrosion that fell into a position that is preventing the valve from closing fully.
Below are links to photos I took when I rebuilt our compressor, showing the corrosion and gunk I found on our check valve. The one thing I wish I had done was to open the exhaust valve to check for and clean any corrosion. We've had a number of symptoms reported that could indicate corrosion in the valve can prevent it from sealing properly. Photo albums 4 and 5 show the corrosion and gunk I found on the check valve and large spring. Photo 2 in the 6th album shows the proper orientation of the piston ring lap joint. Photo album 7 in the links above also shows how the isolation mounts go together, which may help you determine if something is out of order on yours:
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
The document at the link below is the Air Suspension and ECATS section from the '04 XJ New Model Introduction Dealer Training Manual and is the most complete explanation of the system operation of which I am aware:
http://www.mediafire.com/view/7rdkgg...on_Section.pdf
I'll respond to your OBDII thread shortly.
Please keep us informed!
Cheers,
Don
Last edited by Don B; 10-14-2014 at 05:33 PM.
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anindyam (10-14-2014)
#12
10-15-2014, 02:37 PM
I learn something new every day on this forum
Thanks to all who commented. Well, I am going to tentatively resolved, or rather let's say I am cautiously optimistic. Here's mt thoughts: I do not believe that I "resolved" anything by "validating" (AHEM!) the ground strap(s) behind the drivers side headlight as BagPipingAndy suggested. His SUGGESTION was right on the mark, it was my learning that studs attached to the aluminum monocoque are also obviously made of aluminum, and obviously does not take too much torque to twist right off the firewall. ARRRRGGGHH!
Fortunately I was able to mount a bolt (steel) through the frame and set the ground straps on it. Next project: Welding a stud onto aluminum. Not going to be easy I think.
However, since I only witnessed the ASF 2x over 5 days now, and not at all for the last 2.5 days, I want to begin being optimistic and get more so each day I go without a ASF.
Also: Guss: You suggested this:
Just curios what outcome is desired. Are you saying that by sitting a few minutes the pump will fill the reservoir and I likely will NOT get and ASF? Or am I looking to force an ASF to happen? The test seems valid, I am just not sure how to judge if the test was success or not, lol!
Fortunately I was able to mount a bolt (steel) through the frame and set the ground straps on it. Next project: Welding a stud onto aluminum. Not going to be easy I think.
However, since I only witnessed the ASF 2x over 5 days now, and not at all for the last 2.5 days, I want to begin being optimistic and get more so each day I go without a ASF.
Also: Guss: You suggested this:
Just curios what outcome is desired. Are you saying that by sitting a few minutes the pump will fill the reservoir and I likely will NOT get and ASF? Or am I looking to force an ASF to happen? The test seems valid, I am just not sure how to judge if the test was success or not, lol!
#13
10-15-2014, 04:18 PM
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You'll want to use an aluminum bolt as your permanent fix - a shop that specializes in welding aluminum should have no difficulty attaching it permanently if you think that's important. If you use the steel bolt long term, galvanic corrosion will erode the aluminum at the steel-aluminum juncture.
Cheers,
Don
#14
10-16-2014, 12:34 PM
So, this morning was quite a bit cooler out than it has been, and for all you guys who have chased ASF's or have witnessed others doing so, I bet you already know what I am going to say. Yep. Big old ASF sitting there as I get underway today. Not good. It smply HAS to be something that I inadvertently changed while replacing the piston ring.
Looks like I will be under the car this weekend double checking and second guessing myself. Oh well at least the ground strap is eliminated. Need to check the electrical connections, and for my own satisfaction, the output hose. That one brass fitting and what not. Wish me luck!
Looks like I will be under the car this weekend double checking and second guessing myself. Oh well at least the ground strap is eliminated. Need to check the electrical connections, and for my own satisfaction, the output hose. That one brass fitting and what not. Wish me luck!
#15
10-16-2014, 02:12 PM
Also: Guss: You suggested this:
Just curios what outcome is desired. Are you saying that by sitting a few minutes the pump will fill the reservoir and I likely will NOT get and ASF? Or am I looking to force an ASF to happen? The test seems valid, I am just not sure how to judge if the test was success or not, lol!
If you run the car (compressor) for a while the system will fill with air but will not loose (leak) are so you can check if the compressor is able to fill the system within the required time at all. If you still get the ASF if you drive off after trying this your compressor is pretty bad. If the message stays away it's still not 100% but not as bad. It may help you decide how urgent you need to fix it and if you should drive the car. I've driven the car long distances because I knew the compressor wasn't too bad.
Guus
#16
10-16-2014, 07:20 PM
Thanks for the clarfication, and I see what you are saying, but one question begets another, and now I am confused (a fairly normal state for me). In one thread I remember reading that the pump runs once you are doing 15 mph or so, but I also know it runs on startup because when I replaced the piston ring, I only jacked up the drivers side of the car. His eminance BagPipingAndy said this can cause the sytem to measure the car as too high and relieve pressure. In any case when I jacked it down, it looked like a slammed Civic -there was less than an inch between the wheel lip and tire. Note this is the only time the car has ever been low in my experience. Note also that the compressor had it to normal height in about 15 seconds or less, so that bodes well for the pumps ability to pump.
Anyway, your suggestion, plus what I think I know so far have me asking: If the pump can and does run when underway as well as at rest, why would the pump STOP running, just because I didn't wait for it to complete before driving off? I know I have experienced it running while driving. Remember the only reason I got involved with it was the loud pump. I heard it run at rest as well as while driving the car.
Anyway, your suggestion, plus what I think I know so far have me asking: If the pump can and does run when underway as well as at rest, why would the pump STOP running, just because I didn't wait for it to complete before driving off? I know I have experienced it running while driving. Remember the only reason I got involved with it was the loud pump. I heard it run at rest as well as while driving the car.
I was kind of thinking you might ask this ;-)
If you run the car (compressor) for a while the system will fill with air but will not loose (leak) are so you can check if the compressor is able to fill the system within the required time at all. If you still get the ASF if you drive off after trying this your compressor is pretty bad. If the message stays away it's still not 100% but not as bad. It may help you decide how urgent you need to fix it and if you should drive the car. I've driven the car long distances because I knew the compressor wasn't too bad.
Guus
If you run the car (compressor) for a while the system will fill with air but will not loose (leak) are so you can check if the compressor is able to fill the system within the required time at all. If you still get the ASF if you drive off after trying this your compressor is pretty bad. If the message stays away it's still not 100% but not as bad. It may help you decide how urgent you need to fix it and if you should drive the car. I've driven the car long distances because I knew the compressor wasn't too bad.
Guus
#17
10-17-2014, 04:58 AM
Veteran Member
The compressor runs until the reservoir is charged, but is subject to a temperature and also a time-out. If the temperature exceeds a certain threshold, the compressor will shut down until the temperature goes back down. My Technical Notes of 2003.5 says this takes about 30-40 seconds.
In addition, the compressor run time is limited to 2 minutes. If the compressor gets to this 2 minutes, a fault code is normally flagged to indicate the reservoir is taking too long to charge. Normally this indicates the compressor has become inefficient. As discussed before, the seal in the compressor wears, so leakage of air means it takes longer to charge the reservoir. If the system develops leaks then the compressor operates more than necessary and this contributes to wear of the piston seal so the compressor fails at a lower mileage than one might expect. In my case, even with no leaks, the compressor needed replacement at about 35k miles. So far the replacement has been OK and has gone now for 50k miles
In addition, the compressor run time is limited to 2 minutes. If the compressor gets to this 2 minutes, a fault code is normally flagged to indicate the reservoir is taking too long to charge. Normally this indicates the compressor has become inefficient. As discussed before, the seal in the compressor wears, so leakage of air means it takes longer to charge the reservoir. If the system develops leaks then the compressor operates more than necessary and this contributes to wear of the piston seal so the compressor fails at a lower mileage than one might expect. In my case, even with no leaks, the compressor needed replacement at about 35k miles. So far the replacement has been OK and has gone now for 50k miles
#18
10-17-2014, 01:45 PM
The compressor is indeed limited to how long it can run. From what I've read it is temperature related but Jaguar didn't put a temperature measurement in but simply limited the time to max 2 minutes running to avoid it overheating. After a cooling down period it will again run for max 2 minutes if needed.
Others have written under normal circumstances it will run above a certain speed. From my own experience I can confirm that the compressor will also run when the car isn't been driven yet but the system needs filling with air.
There seems to be a situation where the suspension locks down and the shocks won't fill. Driving it a bit will trigger the system to start filling the shocks again so I guess it's something that's programmed in the ASU.
On one occasion I emptied the complete air system (including reservoir). I had all lines disconnected to see how the valve block switched and reconnected each line individually after noticing which outlet was pressurized. First the rears get air so I connected those, then the front ones and then...surprisingly the reservoir wasn't filled. I had the SDD connected and only after driving the car (could be above the trigger speed, not sure) the compressor started again and this time I could see the reservoir valve opening and the reservoir started filling.
Form that I made two conclusions. First the suspension can be filled from the reservoir (as the documentation describes it) but it doesn't have to, the compressor can very well fill the suspension directly too. Second I believe that if the air system is very empty the system will give priority to keeping the suspension filled before the reservoir. This would be logical as this would allow the car to continue as long as the compressor can supply air and keep the car at a certain hight.
Guus
Others have written under normal circumstances it will run above a certain speed. From my own experience I can confirm that the compressor will also run when the car isn't been driven yet but the system needs filling with air.
There seems to be a situation where the suspension locks down and the shocks won't fill. Driving it a bit will trigger the system to start filling the shocks again so I guess it's something that's programmed in the ASU.
On one occasion I emptied the complete air system (including reservoir). I had all lines disconnected to see how the valve block switched and reconnected each line individually after noticing which outlet was pressurized. First the rears get air so I connected those, then the front ones and then...surprisingly the reservoir wasn't filled. I had the SDD connected and only after driving the car (could be above the trigger speed, not sure) the compressor started again and this time I could see the reservoir valve opening and the reservoir started filling.
Form that I made two conclusions. First the suspension can be filled from the reservoir (as the documentation describes it) but it doesn't have to, the compressor can very well fill the suspension directly too. Second I believe that if the air system is very empty the system will give priority to keeping the suspension filled before the reservoir. This would be logical as this would allow the car to continue as long as the compressor can supply air and keep the car at a certain hight.
Guus
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Don B (10-17-2014)
#19
10-17-2014, 06:58 PM
Guus - Thanks once again. In fact I don't mean to sound like I am being argumentative, and I am really pleased you have shared all this knowledge. I also read a bit (I think it may have been in the dealer education PDF that Don linked to earlier in this thread) about a "Slow fill" and a "Fast Fill" The slow is for when you are driving, and smaller adjustments are required (they use the example of fuel tank slowly emptying, but that wouldn't require pumping, but rather venting because the car is getting lighter, but I got the idea anyway. Then the fast fill is for when the car is stationary, and would also make sense if some pressure was lost from a long sitting period of a week or more. This gets the system quickly pressured and ready to ride. I do still wonder about your comment about waiting a bit before driving off - and another post I saw where the guy would get faults "when he drove off quickly" I think I get it now based on the fast/slow fill rates. If it's doing a Fast Fill and you drive off, it will probably cancel the fill since it's programmed to only do slow fill when in motion.
The theory holds until you get to wondering: Why can't a slow fill resolve the air suspension fault, even if it needed to run 20 times, it should still correct it. I ALSO wonder WHY, for petes sake won't it clear an ASF without "sitting for an hour or two. MANY reports have stated that an ASF, once tripped does not switch off until it's given that down time. Sigh. It's not like I am even getting a lot of them. I believe I have had 3 occurrences ever, and over the course of 6-7 days, and perhaps 20 or more trips in the car. It's just a mystery, and I DON"T LIKE MYSTERIES WITH MY CAR. In a good book, yes. In my Jaguar? NO! Keep the thoughts and info coming. I can't ever know too much about this.
The theory holds until you get to wondering: Why can't a slow fill resolve the air suspension fault, even if it needed to run 20 times, it should still correct it. I ALSO wonder WHY, for petes sake won't it clear an ASF without "sitting for an hour or two. MANY reports have stated that an ASF, once tripped does not switch off until it's given that down time. Sigh. It's not like I am even getting a lot of them. I believe I have had 3 occurrences ever, and over the course of 6-7 days, and perhaps 20 or more trips in the car. It's just a mystery, and I DON"T LIKE MYSTERIES WITH MY CAR. In a good book, yes. In my Jaguar? NO! Keep the thoughts and info coming. I can't ever know too much about this.
The compressor is indeed limited to how long it can run. From what I've read it is temperature related but Jaguar didn't put a temperature measurement in but simply limited the time to max 2 minutes running to avoid it overheating. After a cooling down period it will again run for max 2 minutes if needed.
Others have written under normal circumstances it will run above a certain speed. From my own experience I can confirm that the compressor will also run when the car isn't been driven yet but the system needs filling with air.
There seems to be a situation where the suspension locks down and the shocks won't fill. Driving it a bit will trigger the system to start filling the shocks again so I guess it's something that's programmed in the ASU.
On one occasion I emptied the complete air system (including reservoir). I had all lines disconnected to see how the valve block switched and reconnected each line individually after noticing which outlet was pressurized. First the rears get air so I connected those, then the front ones and then...surprisingly the reservoir wasn't filled. I had the SDD connected and only after driving the car (could be above the trigger speed, not sure) the compressor started again and this time I could see the reservoir valve opening and the reservoir started filling.
Form that I made two conclusions. First the suspension can be filled from the reservoir (as the documentation describes it) but it doesn't have to, the compressor can very well fill the suspension directly too. Second I believe that if the air system is very empty the system will give priority to keeping the suspension filled before the reservoir. This would be logical as this would allow the car to continue as long as the compressor can supply air and keep the car at a certain hight.
Guus
Others have written under normal circumstances it will run above a certain speed. From my own experience I can confirm that the compressor will also run when the car isn't been driven yet but the system needs filling with air.
There seems to be a situation where the suspension locks down and the shocks won't fill. Driving it a bit will trigger the system to start filling the shocks again so I guess it's something that's programmed in the ASU.
On one occasion I emptied the complete air system (including reservoir). I had all lines disconnected to see how the valve block switched and reconnected each line individually after noticing which outlet was pressurized. First the rears get air so I connected those, then the front ones and then...surprisingly the reservoir wasn't filled. I had the SDD connected and only after driving the car (could be above the trigger speed, not sure) the compressor started again and this time I could see the reservoir valve opening and the reservoir started filling.
Form that I made two conclusions. First the suspension can be filled from the reservoir (as the documentation describes it) but it doesn't have to, the compressor can very well fill the suspension directly too. Second I believe that if the air system is very empty the system will give priority to keeping the suspension filled before the reservoir. This would be logical as this would allow the car to continue as long as the compressor can supply air and keep the car at a certain hight.
Guus
#20
10-17-2014, 07:05 PM
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I posted this link earlier but the document at the link below has most of the specifics on system performance mentioned by Guus:
The document at the link below is the Air Suspension and ECATS section from the '04 XJ New Model Introduction Dealer Training Manual and is the most complete explanation of the system operation of which I am aware:
http://www.mediafire.com/view/7rdkgg...on_Section.pdf
Cheers,
Don
The document at the link below is the Air Suspension and ECATS section from the '04 XJ New Model Introduction Dealer Training Manual and is the most complete explanation of the system operation of which I am aware:
http://www.mediafire.com/view/7rdkgg...on_Section.pdf
Cheers,
Don
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AD2014 (10-25-2014)