I've got a 2000 Jaguar Stype 4.0 with 80k.i bought it wrecked replaced the entire front end bumper hood headlight grill etc.. Spent almost three grand. Car has set three years and now that I'm driving it I have a miss. I replaced the plugs and one bad coil pack and still have a miss. I noticed the oil cap is white and milky on the bottom also steams while running from the egr and oil fill. I haven't had to add fluid and it's not over heating. What could the issue be? I'm thinking head gasket

 

Not necessarily. First, when you changed the plugs/coils - was there any oil present on the coils? If so, you could have already damaged the replacement coil(s) - any evidence of oil in any spark plug well will require a cam cover/spark well gasket replacements. Second, make sure all the fuel injector electrical connectors are firmly seated in the injector. Are you filling up coolant constantly in the overflow tank? Do you make short trips constantly or longer trips? Short trips can leave condensation in the oil fill tube - what color is the oil on the dipstick? If it looks like mayo, then yes, it could be a head gasket issue. Finally, your miss could be related to the tensioners - these prove fatal to this engine. If the above checks out - you will want to invest getting those tensioners changed out to the metal ones.

How did you determine which coil pack was bad? You may have more than 1 bad or failing coil pack. Good Luck!

 

As said above, if the car has been sitting for a while, the "mayo" may well be caused by condensation. Warm it up well, change the oil and filter and see how it goes.

 

When I changed the plugs they were clean and dry. Coil packs were the same. I found by unplugging each coil pack individually only one wasn't making a difference when plugged or unplugged. After installing all new plugs the car ran even worse. I put the old plugs in and it ran perfect. I just have a miss or stumble every now and then. I also found if I don't run water remover (heet) the car runs awful. I've never had to add coolant and have removed the egr tube to stop the oil and steam from going in the throttle body . I don't see the milky oil on the dipstick just on the oil cap and egr port coming from the valve cover and the engine never runs hot. I'm guessing your talking about the Valve Tensioner? Would those cause the oil blow bye and steam?

 

Sounds like then new plugs must've been the wrong ones.

I don't think you can run without EGR.

That's a really crude way to test coils and won't pick up most faulty ones.

 

Were the new plugs gapped correctly?

 

Open the hood and run water from a hose up near the top on your windshield. If any water is going under the seal at the bottom you'll need to seal it with a black sealant.Water can get in the engine bay and seep under the coil/plug seals and cause a misfire. I have had the same year and engine with lots of misfire problems until I sealed up the coil and windshield areas.