So I just acquired a '00 XJR with 110K Miles, after owning a NA '98 for four years. Would like to know from those of you also have, or have had both NA XJ8 and SC XJRs, is it possible that my XJR in normal mode feels less eager (aka slower) than NA 4.0 in the same mode? Yes the XJR in Sport mode is awesome, but is it calibrated to be extremely tamed in Normal mode, or could it be something wrong with my car?
Moreover, I would like to improve road handling capability of the XJR. In the twisties it's just not precise. Suggestions? Just a more precise front end, without a harsher ride.

 

I never had any issues with power in my 03, but I've never had an N/A to compare to. That said, even with the 2nd gear take off and lower shift points, I never felt the car was slacking in any way in Normal Mode. Putting my foot down in any gear always gave good response. Hopefully others with a direct comparison can chime in.

As for your front end, well there's not a lot of options other than some lowering springs that are out there for the XJR's. However, I would suggest going through all the bushings and bearings first. At 110k miles, if they haven't been done recently there's probably a bit of play in them, even if they haven't yet started making noise yet. That alone might tighten up the overall feel of the front end. It's a heavy car, so there's obviously going to be a different feel than throwing a Porsche into a curve, but when everything's as it should be, it's a joy to dive into twisties.

 

I found 'training' the W5A580 to shift faster and later was a part of it. Mine would slur its shifts, even in S mode and was smooth and would shift up at 5500 rpm.

I took it to the track and started driving it more aggressively and now the car feels faster even in non 'S' mode.

The W5A580 transmission learns and adapts to the behavior of the driver.

 

The XJR uses a Mercedes 722.6 transmission and this tranny is adaptive based on your driving habits. If you feel it is sluggish, you can reset the tranny. See this video link on how to reset, but this is for a Mercedes. Try this to see if it also works on the XJR.


On the Mercedes, it has a 'W' (Winter) mode and 'S' (Summer) mode, (you can see the switch next to the gearshift on the video), similar to the XJR normal and sport. Normal starts from a dead stop on second gear, while Sport starts from first gear.

 

Give the MAF sensor a blast with contact cleaner, and check how much slack your throttle cable to the throttle body is, if you have an OBD reader you can see how much adjustment you need.
Carry out hard reset after these tweaks, let the car idle for 10 minutes then go for a spirited drive.
See how it behaves after this.

Front end, there are a number of bushes, mounts ect that you can work through but to check the condition of your dampers would be the first job, they could be shot.

 

you will notice the car is slower in the normal mode under normal driving. Typically when you mash the throttle to the floor it bypasses the normal mode and utilizes the sport mode for the shift points. Otherwise just drive it in sport mode unless you want to drive like a limo.

 

Not sure if this is relevant, but you should also consider the elevation you're at. There is definitely some performance differences when driving at higher elevations. A simple tune-up with spark plugs, fuel system cleaner, and cleaning some sensors would help.

As for handling, it wouldn't be a bad idea to start with some good tires and an alignment. Then you could replace some of the bushings, possibly even all four dampeners at this age. Lowering the car a bit, and upgrade anti-roll bars are an option too.

 

Dear Friends:

Thank you for all your valuable suggestions. I think I will start with giving the MAF a blast, followed by a hard reset, rehab the 722.6 with a more spirited driving style, and see what happens! Will report back afterwards!

Paul

 

In addition to cleaning the MAF sensor, clean the throttle plate and bore.