I just bought and immaculant 1986 v12 XJS. I am typically a ford mustang man so I dont know much about these cars. Been reading around and learning stuff. But from the pros here is there anything I need to watch for or check off top? Besides the common oil change, tune-up.... Also are there any sites out there that cater to our cars for mods and enhancements? I want to add a little to the car, but not take away from the original-ness.

Any Advice?

Submitted by dougdwyer@adel… on Sun, 05/28/2006 - 14:26

Repacing the cam cover gaskets isn't technically difficult but requires tons of time becuase so much has to be removed to do the job. This is an ideal opportunity to "clear the vee".... clean the valley of the engine of all the debris, replace plugs and wires, service the distributor, replace fuel and vacuum hoses, repair/replace injector wiring, etc etc. Plan on at least a couple weekends......or a BIG bill at a Jag specialist.

The idle surge is likely due to a vacuum leak. Sometimes they will surge all the way to 1500 rpm where the ECU cuts off the fuel. Then the speed drops back down and the cycle repeats.

The V12 does have a TPS but it is not usually the cause of a surging problem.

Cheers

If you did your own work on your Mustangs there's no reason you can't do the same on your XJS but you have resign yourself to working slowly or the car will fight back every step of the way...and be ready for some wierd things you'd won't see on Mustangs :-)

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe

Submitted by nathan.gallowa… on Sun, 05/28/2006 - 13:43

Hi I did notice thaT some of the hoses are showing a buldge in them, so I will addressing that. And it needs valve cover gaskets and has a surging idle after the car is warm (in park or neutral). I know in my mustangs I had IAC and TPS (Idle Air Control and Throttle Positioning Sensor) that I changed to get rid of the surging idle. Does a jaguar have the equivalent? ANd I notice the valve covers are extremely hard to get to. Any tips or advice? Or should I just go ahead and take it to a professional? I know mustangs but dont know jack about Jags.

Submitted by dougdwyer@adel… on Sun, 05/28/2006 - 02:17

The V12 is nearly indestructible *unless* you let it run hot. First order of business is making sure the cooling system is 100% up-to-snuff. Ninety-five percent isn't good enough....you need 100%. If there is the slightest doubt, have the radiator professionally cleaned, replace the fan clutch and thermostats (use the correct ones...important!) and replace all the hoses.

Unless you have evidence otherwise, assume the ditributor mechanical advance mechanism is seized.....and likely the vacuum advance is inop, too.

Go to www.jag-lovers.org and get on the XJS mailing list and download Kirby Palms XJS book

AJ6 Engineering (they're on the web) has performance mods but don't even go there until you are sure the car is running properly in stock form----many of them are not.

Replace all underhood fuel hoses NOW unless you have proof that it has already been done in the last couple years. The bone yards of full of burned out XJSs because this wasn't done.

These are fabulous cars...built like a tank and have many fine qualities....but they do have quirks and require TLC. Sadly, most have been neglected in terms of repairs and routine service so new owners need to spend time getting back to square one. Once you've done that you'll have a reliable Jag.

This just barely touches the surface. If you have specific questions or problems give a shout.

Doug Dwyer
Longview Washington USA
1987 XJ6 Ser III
1988 XJS V12 Coupe