Cheers Guys.

Well, Last thing before I left I found a NTK 4 wire sensor that was for a 1.6 306, Cut the plug off and connected it up to the original plug off the Nissan, Then I took the sensor earth lead back to the cylinder head as I'd thought about earlier. started the car up, ran it at cruise and bingo, The sensor came on line, The motor felt and sounded crisp again.



The O2 output wasn't great at idle but much better than before. I hope its just a matter of fuel trim which will improve with a few drive cycles. A quick burst up the road and tried it for the MOT which it flew through.

What's the general opinion on the fix of using the 4 wire to improve the earth? I wouldn't have done this but that car really isn't worth a lot of stripping to sort out a decent manifold earth!

Cheers.
Steve.