Hey Team, I hope all is well! I have a 2002 Jag S type 4.0 with 195,000KM. Car has been a dream up until now. I noticed a few weeks ago that the car has an irregular misfire. It is very noticeable when it is hot outside and there is a load on the car (A/C on, passengers etc). It seems as if the power is gone! I notice it on acceleration, climbing hills and idling.

There is no check engine light. Nothing showed up when he hooked it up through his computer. My mechanic checked the throttle body and said it wasn't dirty. He has no idea what it could be. I changed the Spark plugs to NGK Double platinum at 150,000km when I did a tune up as well as replaced the fuel filter. Other then that, I replaced the a/c compressor 2 months ago... no idea if this anything to do with it!

Any ideas what it could be, or what can I do to fix it?

 

Check your plug boots. They could be bad. In fact, replace the boots as a preventative.

 

Is this the same as the ignition coils, or is this different?
http://cgi.ebay.com/ebaymotors/ws/eB...tchlink:top:en

 

Nice picture by the way. No. You should be able to purchase the plug boots separately. I would try those first an then go for the coil, although from what I've heard, the coils have a tendency to fail as well. Being that you had such a rapid loss in power, it could be the coils.

You should only need one or two of them. Due to $$$$, I would replace only the ones you need. Have a mechanic do a live stream or have him read the memory in the computer for events that have occurred recently to determine the cylinder where it is happening.