Stu live mapped it - it was running too lean originally which was leading to the det. I have every confidence that the map is correct, as when I drove her away - she was det free. Maps dont just undo themselves, which leads me to believe that this is a separate issue with similar symptoms.

Before I rip the head off, I am gonna borrow a wideband lambda and also check the fuelling to make sure something hasnt gone adrift on this side of things.

I am mindful that I am only using a Gp A headgasket (as an experiment to be honest), so I wasnt expecting great things.

JJ