I haven't been on here for a while since I was pretty discouraged. My 04 xj8 was off the road after it cut out on me months ago and refused to start. That turned out to be a bad crankshaft sensor.
I realize these cars are prone to throwing codes and I accept that. I keep an obd2 tester in the car.
So...after a couple hundred miles of running great, I parked at my job yesterday and came out a couple of hours later to run an errand. The yellow light was on and i had a message that my performance was restricted. My code reader told me it was a misfire on cylinder 8, and that the fuel injector was open. There was an obvious misfire when i first started the car, but it seemed to smooth quickly. i drove carefully to my errands, reset the codes, and after restarting a couple of times, the light went out, the warning was gone, and the car ran fine. Then the same thing happened again today, this time after 20 miles or so of driving fine, then parking for an hour and a half. As soon asi started up, the yellow light and performance message were on. Same code, same cylinder..
cleared again, and it ran great.
is this likely a problem with the injector,, or maybe a wire? Could it be the ecm? What does anyone think? Suggestions?
thanks!

 

Hello,

But did you already checked that spark plug on cylinder 8? That would be a starting point, also check the wires. Your description doesn't look like something so serious so far but it could be if you reset the code instead of trying to figure out what is causing the issue.

J.A.G.

 

I would do the same. Check spark 8. Maybe it was to difficult to change for some one and it es very old?
I use fuel injector claener every 5000Km. I would give it a try. Its easy and cheap.

 

+1 on that # 8 spark plug, that one gives many problems removing it.

 

I appreciate all of the responses. It makes sense that the plug could be a problem, especially since it cleared and started firing again. My 01 f150 has a couple of plugs that are hard to get at, and when I changed them all there were two that looked like they were skipped over previously.
Fuel injector cleaner probably wouldn't hurt either! Thanks for your suggestions!

 

It would be better with the actual code. It sounds like the ECU thinks there is a bad circuit on the injector - possible connector/wiring issue or injector on the way out.

 

I don't know how modern fuel injectors are wired-up, but on the old analogue L-Jetronic system, 12 volts was supplied to the injectors and the ECU triggered a pulse by earthing the injector through a transistor and a resistor. If this is still the case, albeit now digital, it is very easy for a modern ECU to detect an open-circuit injector, as there will be no voltage detected for that injector at the ECU. Injectors no doubt fail, although, (touch wood) it has never happened to me. Plenty of other things have happened though in my Jaguar-owning life!!

 

First, thanks to all who are so helpful with your knowledge and experience. I am often intimidated by this car (04 xj8) it's easy to jump to the conclusion that any problem is going to be expensive, and/or difficult to diagnose.
in this case, it was pretty obvious. The cylinder was misfiring intermittently because the wire to the injector was not firmly connected! It pulled off with no resistance, then snapped back into place. The problem has not come up again since.
thanks again for your replies!