Quick question.. I have a 2002 Jaguar XJR with a intermittent delayed throttle response. Upon acceleration it read ASC and delayed throttle response by 4 or 5 seconds. I’m changing speed speed sensors this weekend. Does anyone know what I should do if problem persist?

 

Check the diaphragm rings between the supercharger discharge and inter-coolers.

 

Sounds like the system is working as intended.
The ASC illuminates and the throttle is retarded when there is loss of traction at one or both rear wheels!!

Try disabling the ASC and perform the same maneuvers?

You will likely get some wheel spin but the ASC will not intervene.

 

[QUOTE=motorcarman;2380663]Sounds like the system is working as intended.
The ASC illuminates and the throttle is retarded when there is loss of traction at one or both rear wheels!!

Try disabling the ASC and perform the same maneuvers?

You will likely get some wheel spin but the ASC will not intervene.[/QUOTE

Thanks for responding! Sadly it is not functioning properly... I talked with a specialist and the ABS control module had to be sent to be rebuilt. This a common fault on this xj series in general. It will be about $400, the car is drivable but with jags it’s better to have it fixed then have it fault something else.

 

X300 XJRs (1995-1997) are the most reliable of the bunch, but it’ll be tough finding one with low mileage at this point. Mine has almost 200k on it. Most of the time, unless it was owned by an enthusiast, there will be a lot of deferred Speed Test maintenance.