I have a ton of reading to do on this topic, but wanted to post my situation briefly as I dig around and educate myself.
Dreaded air susp fault message appeared on my 140K 2008 XJ8 last night and I tried my AD310 ODB reader with no luck. Read a bit and appears not many OBDs read the Jag prop codes.
The two front air struts were replaced at 100K but two back are original. It appears the driver rear is mostly affected. I took measurements this morning before turning on the car and then fired her up, let run for a bit and then took new measurements.
Measurements are from ground up to wheel arch.
27 1/8" 27 5/8"
25 5/8" 27 1/8" // Not a typo… 25!
Second reading after start and idle time
27 1/8" 27 5/8"
26" 27 5/8"
So, fronts stayed the same and rears went up 3/8" and 1/2". The driver rear is noticeably sagging and almost 1 1/2" lower than rest of car.
So anything to deduce from this? Does this possibly imply leaking rear bag since one of 4 wheels is more affected than others… or could a bad pump (most common issue I believe) end up inflating the bags unevenly.
Also I have a good Jag mechanic, but still expensive. Any idea if pulling true Jag codes will answer any of my possibilities listed above?.. or in other words, are the codes granular enough that it will tell me “bad pump” versus “leaking strut bag”
One last point. When I fired up the car I went to back most sagging wheel and there was a VERY notable hiss of air. Ran around other three and kind of heard air “filling” type sounds, but nothing as loud as driver rear… like a bike tire with a flat losing air. Then the pump stopped pumping as I listened in front and then hiss at back wheel stopped also.
Maybe I can get her up on stands in back, fire her up and see if I can locate the hiss location. Maybe just a hose attached to the strut bag??
OK, thanks for those willing to ponder the evidence… “The game is afoot Watson!”
Randy in Raleigh