Hi, I have a 2005 XJR that has just given me an all-round lowering of the car, with a car too low message, overnight, on 2 occasions, separated by 4 days/nights with no problems. The car started up fine but displayed the car too low message, until it rose up back to normal height on both occasions and was fine for the rest of the time. The car is a daily driver covering 30-40km daily.

I was thinking that the cause may be from a leak in a common pipe, valve or reservoir, but I can't understand why it was fine for 4 days before the second occurrence, and am wondering if it could be an electronic controller issue as well.

Our temperatures here are 80F (more or less) and we have no winter, although it has been very wet for the past month. This last week however was relatively drier than the previous weeks though.

The car has had 4 Arnotts shocks and a new compressor put in about 6 months ago, and has been fine since then. No work has been done on the car, except for the car being sent for polishing / detailing the afternoon before the first occurrence of the suspension being too low.

Can anybody suggest where I should start troubleshooting? Thanks.

 

Are you sure it was all around? How much. The way the system is plumbed that is virtually impossible. One corner but not all. Let it pump up, measure the heights at the highest point of the fender arch at all corners. read them again in the morning and report back.

Eddie 04 VDP

 

Yes all round lowering. I've already been through the tedious exercise of troubleshooting asymmetric height differences between the left and right side, and the front and back earlier in the year, resulting in the change of all the shocks and the pump 6 months ago. That's why this surprises me as well, to have all 4 go down simultaneously overnight, and only on two nights, separated by 4 days with no problems.

I'm wondering if there could be a erroneous command signal that is activating this intermittently.

 

You would have to get a ground to 5 solenoids at once. Very abnormal. Any codes?

 

The car does occasionally wake up and check that it is level and adjust accordingly if it is not, so it is feasible for the car to sit low on all four corners as it can only lower the car to compensate in sleep mode.

I would assume therefore that if you have one leaking spring the car will eventually lower the others to match.

 

My 04 VDP did that.
Last month, I turned off the ignition and watched as the LF shock lowered, then the RF started to lower, then both rear shocks lowered to match.
I started the engine waited till all shocks were fully inflated and the car level, turned off the ignition...disconnected the connecter to the valve block and within half an hour, I found the O-rings were bad at the air-line fitting on the LF shock. The LF shock lowered and the other 3 stayed inflated.

 

That is true but it will only go so far. It should not lower enough to create a vehicle too low condition.

 

It lowered all the way 4 times before I did my little experiment.
Got the Warning all 4 times till the suspension was a few inches higher. The first time it lowered, I was at work, had to drive home slowly cause the suspension did not lift.

I would love to install some type of manual control for each shock.

 

Unfortunately my back-up car is in the workshop currently for long awaited mods so I haven't been able to send the Jag in for checking yet. Just hoping it won't get worse for another week, when the other car hopefully comes out. (Of course the Jag has to pick this week to misbehave....)

 

Oh no.... just when I thought I had the problems from 9 months ago resolved.... Looks like another round of air leak detection....

 

Did you have days in between where the car seemed ok? It could of course be that I'm just at the early stage and the problem is going to recur more frequently...

 

It is possible. I have considered it myself. I now think I will have to get a new/used compressor. Coilovers are looking better and better.

 

Happened again last night. All 4 corners lowered until about half the rubber of the tyres is above the lower edge of the wheel arches for all 4 corners. Hope my back-up car comes out ASAP this week so that the jag can go in.... sigh...

 

Try leaving the battery or the solenoid block disconnected overnight and see if it still does it. If it does then that would confirm a leak.

Eddie 04 VDP

 

Thanks for the suggestion. I'll try that if the problem becomes more consistent. Right now, as it happens once in 3-4 days I wouldn't know if it's ok because of the disconnect or because it just wasn't time for the problem to show itself again.

 

It lowered every time the temp went below 50 degress F.

I got the left repaired but now the right shock is leaking at the top, but again, only below 50 degrees F.
I tested the temp theory twice last week and this past weekend, as last week the temps were below 40 degees F and this weekened the temps were above 50 degrees F. Last week, I moved the XJ in and out of the garage to check the leakage. Left it out for an hour and the front went down all the way. Moved it back in the garage and it stayed inflated.
Does anyone have an old front shock (not usable) laying around? I would like to tear it apart to see what components/areas are causing them to leak.

 

Using soapy water, the leak is from the tip of the arrow indicated on the attached photo.
Looking at other photos of front shocks, there is a small hole near that point.

 

That's interesting. Does anybody know what that hole is for and if it should be venting air?

 

Those are not vents. Theyre just holes in the top of the shock mount over the foam upper shock bushing that is also open all along the side inside the center ring for the shock nut and shaft. That is a captured bushing idf there is a air leak in the top of the mount behind that bushing it is not repairable. Be sure and tighten that shock nut on the shaft because that lets the top plate come loose inside, and verify the air line and adpter it threads into are not leaking. These are also 2 leak points

 

Brutal
Have you dissassembled one of these. I looked at the one I took off and it appears it will take a cutoff wheel.