So over the past week or so I have been struggling with what turns out to be an ignition misfire on my MY94 XJ6 but I did not know what was causing it.
My initial thought was that I had some sort of fuel supply issue. So this evening I swapped my fuel rail for a special one where I have drilled a extra fuel tap port back by the fuel supply inlet on the rail and hooked up my pressure gauge to the system.
But after doing that, I started the car up and ran it for a while it in my shop but the fuel pressure did not seem to be the smoking gun I was hoping for. But just to make sure I left the special fuel rail on the car and drove back home from my shop.
Midway home the car started acting up again so once I reached home, I left the car running in the driveway while I popped the hood open and prepared to hook up the fuel pressure test gauge.
Just before I hooked up the fuel test gauge, I reached over and manually twisted the throttle with my hand. At this point it is very dark and there are no lights in the area when I park this car in my driveway.
As I twisted the throttle while leaning in from the driver’s side of the car, I noticed some small blue sparks flashing over on the front of the passenger’s side inner fender.
So I walked around to the other side of the engine compartment and again leaned over to gave the throttle a twist with my hand while I watched the inner fender for the jumping sparks.
Ah HA! There are twin sparks jumping across from the inner high voltage tower on the coil to both the positive and negative low voltage posts on the coil!
So now I have my smoking gun as to the cause of the misfire and just have to try replacing either the ignition coil and/or the ignition leads.
My thought is that it is the coil but I will just have to see what happens when I examine it closer tomorrow when there is more light.
Are the coils used on the XJ40 anything special or should a standard coil function fine?
Steve