I recently had the opportunity to go really fast in my 2003 XJ8 (X308). The car gets to about 115 mph very quickly but then appears to hit the speed limiter. I had thought that no speed limiter was fitted to non s/c X308s?

 

Shouldn't be a speed limiter at that speed. Mine went just under 140 mph with no issue. I'm sure other guys will chime in that theirs can do that with no issues either. Maybe yours isn't running on all cylinders. Check engine light on?

 

Speed limiter is 155mph you should be able to get close, I can hit it in my XK8 and there's not that much difference

 

Bad ignition coil ,fuel problem ...i would check that.

 

The car runs smoothly and accelerates really hard in the low gears close to redline. Mpg is where it should be. No CEL or trouble codes, new spark plugs, valve cover gaskets and seals, rebuilt TB, new fuel filter. It feels just like my 1994 Ford Crown Victoria which was limited to about 108 mph because of tyres, all of which points to a speed limiter which should not be there.

 

I'd suggest a trip to the dealer, it might have had a lower than E.U. restriction sometime in it's life, if so t's easily removed with their diagnostic kit.

 

that seems suspiciously close to the Japanese speed limit of 180 KPH approx. 112 MPH

 

That's a very good point, however the Japanese are right hook like us....... Unless there is some story behind it?

 

There is one story, the car is ex-lease, I know that rental or fleet cars are low speed limited but I doubt that lease cars are.??

 

03 XJ8 sport. I experience the same thing at 115 mph. It as if you've hit a speed limiter it's very smooth and subtle but it will not allow the car to go over 115 mph. So just chiming in that you're not alone I know it's an old thread but just letting you know maybe it's related to the 2003 model year.