My 05 XJ8L Super V/8 shows an ECATS fault displayed the last 2 mornings and seems to ride stiff in the back. After 10 minutes of driving the message and the amber light go out and the ride is normal. Stays off the rest of the day even if it sits for 4 to 5 hours. Anything to fret over?

 

Best to get the stored fault codes read, just in case something is on the way out. If you get a CATS fault, this causes the system to default the shocks to 'Hard'. The shocks are switched from Hard to Soft by application of a voltage to each shock. This switches a valve inside. No volts means they default to 'Hard'. What seems to be happening with your car is CATS detects a fault, but when the fault condition disappears, it acts as normal and switches the shocks to 'Soft'. I have no idea what might be causing the fault.

 

It recently had the right front air strut replaced. Should I start there for a poor connection?

 

What was the replacement ? Only the Bilstein OEM units support CATS.

 

AHHH!...... Well it was installed prior to my purchase. The upper mount is a tapered silver rather than the round black top on the right. So it appears to be a non Bilstein unit. Should I be concerned?

 

You should not have mismatched air springs like that, as the CATS system can only function on the three Bilstein units. Not only that, the two air springs will probably not be matched. As you have a Super V8, you will probably have the "Sport" units not the "Comfort" ones, but the aftermarket one is unknown, but in all likelihood different to the Bilstein.


The aftermarket one was probably installed with "spoofing" to prevent CATS fault displays, but doesn't seem to be working with your car. If it were me, I would get the stored codes read, and then action can be taken. You have a choice - put another aftermarket unit on to match the other one, or replace the aftermarket one with a Bilstein unit. The CATS on the X350 cars does not necessarily switch all shocks from Hard to Soft. If you brake hard, it will switch the fronts only to Hard, and if cornering it will switch the outer shocks to Hard. It's much more complex than CATS on the previous model.

 

From what I can determine, it's an Arnott unit. My understanding is the Super V/8 got comfort shocks and the R got sport. This rough ride is happening every morning on the first 20 minutes of driving. Just before getting to work the message disappears and never returns for the rest of the day. It also appears that its not the rear but the front that's stiff because it seems low in front in the morning.

 

If its an XJR, it should have the Sport air springs, (Red Spot on the unit). What the Arnott unit is only Arnott can tell you. I don't think Arnott would recommend only a single one of their units is installed, it would normally be all four replaced, (or with steel coil units, of course.). You might manage to find a used Bilstein to put on the front, or even a NOS unit. Brand new ones from Bilstein cost quite a lot.


First thing, however, is to get the stored fault codes read and interpreted, before spending hard-earned $$$$

 

OK I knew this was a suspension thread so I didn't want to read it but can we all agree the thread title is misleading?

 

I thought the 'double-meaning' might come into play, kinda like the Lee Greenwood song about him 'taking his baby on a morning ride'..................

I just did not want to take this post in that direction!!!!!!!!!!!!!!!!!!!!!!

bob

 

How 'bout "stiff and lopsided" in the morning then?

And that's before we get out to the car

Yes, I am helping the OP ... by bumping this up.