I have a 2000 XK8 with 145 k on it. It dropped a valve seat and I replaced a head, timing chain and all timing chain tensioners and guides. Anyway now it runs well in restricted mode without a crank sensor and stores code p0335 as it should. With a crank sensor I get random misses on all 8 cyclinders, codes p0301 thru p0308, plus code p1316, and after a few minutes it drops into restricted mode. Apparently the timing between the crank sensor and the injectors or spark is off. It runs fine when it gets the timing input from the cam sensors when there is no crank sensor in it.

 

I didn't realise it would even run with the crank sensor out , you learn something everyday. Now that I do know, I would take a stab in the dark that the cam timing is out. Seeing as you have worked on the timing chain I would double check that first. your statement about the spark timing is part right i suppose, its just that with the cam timing out, for some reason using the timing from the cam is less likely to cause a misfire than from the crank sensor

 

I originally thought my new crank sensors (2) were bad, until I pulled the old one out and started it with it hanging out the bottom of the car. Apparently the timing between the crank and the spark or ignition is off.

 

Does anyone know if the car uses one or both cam sensors when the crank sensor fails, and if so, which one, Bank A or B?

 

Knew I'd read this somewhere.

From the training manual on Gus' font of all knowledge:
Jaguar V6 / V8 Engine Management #881


"In normal operation, the ECM uses the inputs from the crank sensor and the A bank cam sensor for cylinder identification
and ignition/fuel synchronization. If the A bank sensor system fails, the ECM switches to the B bank inputs. If
the crank sensor system fails, the engine will start and run using the inputs from both cam position sensors."

HTH,

Mike

 

Going to disconnect A bank cam sensor and see if that helps. I know it runs well without the crank sensor. If it is still rough it's either the ECU or the flex plate??

 

An update: Connected and reconnected all sensors and took the ECU completely out of the car to make sure it had no power to it, placed it back in the car and it is doing a lot better. Not yet perfect. Now I am getting codes that Bank A and B are to lean. I suspect dirty injectors.

 

Hi Swampjag,
I wouldn't recommend removing/replacing modules with the battery connected. Safer to do a hard reset (remove negative terminal from the battery post and hold against the positive battery post for 30 seconds) and work with the battery disconnected.

Lean A and B could be an unmetered air leak. Others with better knowledge than me will chime in and point you in the right direction.

Good luck,
Mike

 

Thank you. Also discovered that the ECU is not original which makes me wonder if the mileage on the car is stored in the ECU or somewhere else.

 

AFAIK the mileage is in the instrument cluster only.

Did you inherit the problems with the car, or did it run OK before the head change?

Mike