This XJS has the newer electrical system. The car feels like it is not running on all 12 cyclinders. The radiator light comes on, but I have plenty anti-freeze and water and the temperature guage reads normal. I've been told to replce the catalytic converter, the coils and oxygen sensors. The car has only 29,000 miles on it and is used very rarely in the summer months.

I'm open for suggestions before I start putting alot of parts into the car.

Submitted by dougdwyer@eart… on Sat, 01/25/2003 - 11:28

Me again. Sheesh. What a dope I am. I just re-read your subject line. I had it backwards....I thought it was rough UNTIL it warmed up. I see now that it is rough WHEN the car is warmed up.

Could still be a coolant temp sensor. If the sensor thinks the car is cold when it is not, the end result will be over-fueling and rough running....almost certainly accompanied by black smoke.

Are you getting black smoke?

Cheers
Doug Dwyer

Submitted by dougdwyer@eart… on Sat, 01/25/2003 - 11:21

Oh, one more thing....

If the engine runs OK after warming up, my first guess would be a faulty coolant temp sensor, as this device plays a major part on controlling fuel mixture until the engine is fully warmed up.

As guesses go, this one is cheap and easy....one of the few that are.

Good luck

Doug Dwyer

Submitted by dougdwyer@eart… on Sat, 01/25/2003 - 11:14

I just bought an XJ-S myself and am still learning, so don't take this as gospel.

The Marelli igntion system is a bit fussy. If the system is not kept absolutely up-to-snuff, misfires occur and unburned fuel ends up in the catalytic convertors, which promptly over heat and clog as a result. The oxygen sensors can also become fouled....but they should be replaced every-so-often anyways. The dist cap, rotor, plugs, plug wires, coil...everything...must be "just so" with this igntion system or big troubles will result. Even a slightly incorrect spark plug gap can create havoc.

I'm not usually an advocate of wholesale parts replacement but, if your ignition parts are original, I would want to replace them just on general principle, even if this doesn't solve the issue at hand. Beyond that I'd wait for advice from a more experienced XJ-S guy.

I think the coolant warning light issue is unrelated to your driveability problem.

Hope this helps a little.

Doug Dwyer
JDRC/NWA