Hello,
I am driving a 2003 Discovery II and recently Cylinder one and eight are misfiring I am getting the following codes P0300, P0301, and P0308.
Can the Camshaft and Crankshaft position sensors be causing this issue? The car has 175000 Miles.
Any suggestions would be appreciated.
Thanks much

 

I think if the crank position sensor fails you won’t get any spark. I’m not sure what happens if the cam pos sensor fails, but I don’t ever remember reading about a cam sensor failure.

 

Check wires and plugs first. Definitely pull 1 & 8 plugs to inspect, but maybe pull the whole set, read the plugs, then install a new set. If wires are old, replace those too, especially if the ends look rusty. Those are basic tune up tasks, it's good to start with the basics before diving into sensors. How old is your air filter? How clean is the thottle body plate and passages?

 

I agree with John to a point. One thing to understand is that if you replace a bad plug wire then you have actually solved a base problem and you are now good. If you replace a couple of fouled spark plugs, you might make the engine run well, but will it last? If the plug failed due to, say, oil fouling from a bad valve seal, then you just threw good money away to buy new plugs that will foul again in a short time. It is usually beneficial to try to find the root cause of a problem. Then at least you know that those new spark plugs will soon foul again and you are right back where you started. For your current situation that might be enough, and sometimes it is for me too. That's for you to decide. I always know that at some point, though, I'm gonna hafta do it right.

In this case:
- swap a couple of plugs locations and see if the misfire follows the plug
- Swap a couple of plug wires and see if the missfire follows
- Read the plugs - all of them - as John said
- if there is oil fouling, do a compression test...or do it anyway.

Those things will tell you a lot, and will likely tell you what needs doing to solve this.

 

Thank you all. Let me work on those suggestions...appreciated.

 

Good suggestions for troubleshooting. If you give us a bit more history we can provide some suggestion. Essentials are PCV valve mod if not done, Plugs wires and coils last a very long time but not forever.