94 Jaguar XJ6 Vanden Plas Problems



Hi ,

I recently ran into problems with my dad’s Jaguar.

I was heading on a freeway to a local market when I noticed the car wasn’t accelerating all that well.

I didn’t really mind much at first…I arrived at my destination and did about my errands.

When I was leaving I noticed

the car wasn’t revving properly it barely revved to 2,000 rpm , and my top speed was only to about 15-20mph range.

Couple minutes later the engine check light came on…I pulled over and checked the Transmission Fluid & Engine Oil levels , but it was fine.

I even tried flooring the gas pedal , it didn’t do anything but waste gas. The engine sounds like its mis-firing , could it be the spark plugs? or maybe even the fuel pump?

If it helps , I know the car only takes in Premium Gas but my dads been filling it up with 87 Octane then the recommended 91. I filled it up with 91 today. Any help would be appreciated ,



If your father has been putting in gasoline of the wrong octane level, is it possible that he has also been cheaping out on maintenance? You did not provide any details on the maintenance of this vehicle, but that would be a strong suspicion on my part. Throw a vehicle that is…let’s just say…not among the most reliable into the mix, and you have lots of possibilities here.

If the CEL is illuminated, that means that a trouble code (or codes) has been stored by the car’s on-board computer, and those codes are the key to the diagnosis. You can have the codes read free-of-charge at some auto parts stores, and that would be a good first step to having this problem resolved.

If you post the codes here on this forum, people will be able to give you specific advice, rather than making random guesses. Acting on random guesses usually results in making multiple repairs, many of which may not be necessary. Finding out the exact trouble codes leads to a solution to the problem.


That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here.

I doubt if it is an octane issue.


Well Gollee,
yes to the others and maybe…
dirty gas /gas filter maybe MayBE