Hello, here's my new XJS - got it delivered on Friday and I'm enjoying it very much so far
Couple of issues I've noticed:

1. Hunts a bit at idle, don't really notice the revs go up much but you can hear it
2. Can't seem to get the cruise control to work
3. Aircon seems to do very little, the two vents on either side seem to blow no air at all.
4. Don't know if this is by design, but when you turn the lights on, a dash light shows they're on but this light then goes off after about 15 seconds which I find a bit weird?
5. Can hear a squeak coming from the passenger side (RHD car) while accelerating.

Apart from that, enjoying cruising around town at 11 mpg!

 

Hunting at idle copuld be a loose vacuum connector or pipe. That 15 second light is the bulb failure warning....it is normal, if it doesn't go out it means you have a failed bulb somewhere. A/C in these cars will always put out more at the center vent then the sides but you could have some flap issues...turn the temp control knob slowly up and down and you should here some servo's wirring.

 

Cheers, I'll test my flaps tonight! Not sure where to start looking for vacuum hoses but I can see if there's anything obvious.

 

Nice XJS




The "could be" list is rather long.

Besides a vacuum leak you'll want to check that your throttle bodies are clean and the throttle blades set at the proper .002" gap. This is a good time to adjust the linkage (easy) and replace the throttle bushings (bit of a fussy job) as they're almost certainly deteriorated. Unless, that is, they've already been replaced.

Years ago I had a slightly rolling/oscillating idle on my V12 XJS and replacing an oxygen sensor fixed it. I can't remember exactly what brought me to replacing it, though. Desperation, perhaps.






Most often the bellows is leaking. Easy job to reseal.

More info here:

Cruise Control






If you're asking the system for full cooling then 95% of the output should be thru the dashboard center outlet.

Is it?

Conversely, when max heating is called for, most of the air should come thru the footwell outlets.

You'll notice most output from right and left dash outlets when the system s set to something other than max cooling or max heating.

All that said, do you sense that you're getting maximum fan speed? There are two blower motors. One of both of them might not be fully operational....either becuase they are faulty in some way or because they are not being commanded to maximum speed.






Bulb check system, as already mentioned.

Another weirdness: if you apply the handbrake and then apply the footbrake, the dashboard light should come on. This is the check for your brake light bulbs.

Cheers
DD

 

Obviously these cars are not fuel misers.

However.....

Unless your being rather heavy-footed and/or driving only in city traffic, that figure seems a bit heavy to me.

Driven *gently* my XJS would give 12mpg in city driving and 19-20mpg on a long highway cruise...sometimes as high as 22-23mpg if conditions were ideal. That's USA gallons. This would be about 14mpg and 23-24mpg using your Texas-sized imperial gallons .

Just something to think about.

OTOH, if you're driving hard, 11mpg is entirely plausible.

Cheers
DD