Restricted performance light on , jaguar XJ8 1999

[fast cars]

Out of the blue this light has come on, no other faults still runs well but would not rev high.

Any ideas on what I should look for to fix

cheers

[Jaguar steve]

XJ8 or XJR?

You need a OBD2 scanner - ebay, about £20.

If the car is fitted with cruise control it's possibily the brake light switch. There are actually two switches inside the assembley, one for the brake lights and one to disengage the cruise control. If the two actuate at different pedal positions due to contact wear this will trigger a restricted performance message and amber warning. A failing or out of spec AFM will too, but there could be dozens more faults - you really need it scanned.

BTW: The R will not rev over 3k in neutral as a design feature - not a lot of people know this and assume there's something wrong when they try.

[Ian350]

I had this. The can be many causes but in my case there was an air pipe hanging off. Try looking for this or splits in pipework.

[fast cars]

Thanks Ian and Steve again, i will investigate broken pipe, re OBD scanner - Steve is there a particular one you can recommend, there seem to be many on line, do these also let you reset a fault? if that makes sense.

Cheers
Danny

[fast cars]

just to add, It would be good if this tool could could plug in to jaguars from the XJ40 (if they have a connection) and then X300 to X308. thanks again

[Jaguar steve]

To the best of my knowledge OBD2 compliancy became a requirement on petrol engined cars in 2001, although the X308 was compliant from launch. Earlier cars need the Jaguar WDS system for diagnosis.

I have an Autel Maxi Scan MS 309 which I know works on my X308. The advantage of this one is it not only displays the fault code but actually tells you what it means although there are still some Jaguar specific ones you have to look up on Google.

IIRC Cost about £18 from ebay, and yes it will reset fault codes and warning lights.

[fast cars]

http://www.ebay.co.uk/itm/LATEST-VERSION-BUS-CAR-F...


Hi Steve, just ordered this Autel scanner, should do the job??

[Jaguar steve]

fast cars said:

http://www.ebay.co.uk/itm/LATEST-VERSION-BUS-CAR-F...


Hi Steve, just ordered this Autel scanner, should do the job??

Can't see why not. OBD2 is OBD2 so any scanner ought to work.

[fast cars]

Steve , always appreciate your help. cheers Danny

[SV8Predator]

Jaguar steve said:

To the best of my knowledge OBD2 compliancy became a requirement on petrol engined cars in 2001,

No, that was EOBD in 2001.

OBDII and EOBD are not the same thing.

[Jaguar steve]

SV8Predator said:

Jaguar steve said:

To the best of my knowledge OBD2 compliancy became a requirement on petrol engined cars in 2001,

No, that was EOBD in 2001.

OBDII and EOBD are not the same thing.

You're quite right - I was confusing the American and European requirements and the relevant dates

[skeeterm5]

This sounds similar to the issue that Mike Brewer had with the XK8 he did up on Wheeler Dealers. If I recall it turned out to be a throttle sensor.

Might be worth googling the episode....

S

[Gramrugby]

I had similar, was ignition coils.

[AmitG]

skeeterm5 said:

This sounds similar to the issue that Mike Brewer had with the XK8 he did up on Wheeler Dealers. If I recall it turned out to be a throttle sensor.

Might be worth googling the episode....

S

There was one episode where he bought an XK8 (complete with "restricted performance" problem) off a retired chap who had bought it as a "project" but had found that it was too complicated for him to work on. I think it turned out to be the throttle body itself. Ed China took the car to Jaguar and got a full diagnosis done which narrowed down the possibilities, then bought a throttle body off eBay and fitted it himself, which cured the problem.

Ed's view was that it was better to take the car to a dealer and get a proper diagnosis than to waste time and money replacing parts needlessly.

Funny how I can remember all this but I still can't remember SWMBO's birthday

[skeeterm5]

Thats the one, and somewhat unbelievably it was on sky this afternoon.

S