Having this situation: Sometimes she starts w difficulty, a lot of cranking going on. Another problem, oil in garage. If the main front oil seal leaks, could it saturate the crank sensor w engine oil? Gonna tell my mech. about all this and see what he thinks, and report back. Otherwise, car runs great, pull strongly, beeps when I back up, annoyingly. Drives well, very well. It's a 2004 xj8, high pedigree automobile.

 

It could be the crank sensor, they can cause all sorts of problems when they start to go, had cars that were difficult to start when cold, but ran fine once started, and others that would start ok when cold but not when warm. doesn't always throw up a code either. if you suspect the sensor, I'd change it, It could be oil contamination, or just a coincidence and the sensor is bad anyway, but I'd try to find exactly where the leak is coming from and sort it, hot leaking oil can damage sensors and wiring, and perish hoses.

 

I'm going through the same saga with my 2004 XJ8. I've taken the diagnosis to the point of knowing that I don't have spark when it refuses to start. I've got good power and ground at the coils but the ECM is not commanding spark. That basically means that it has to be a crank sensor or a problem with the ECM module / harness. The trouble is that every time I hook up my laptop diagnostic software to watch the RPM signal the car decides to start just fine.

 

Thank you to everyone. I will report when success happens.