Technical Pinking on Part Throttle

[hot_fiat]

My 20v has started to pink on part-throttle when labouring. Full throttle clears the problem (probably as the detonation sensors'll kick in). The old girl's done 138k but for the last 100k has regularly received the redline treatment so in theory it shouldn't be coking but I'm slowly coming around to that diagnosis.

Before I resign myself to taking the head off and getting the toothbrush out, does anybody have any other ideas what it might be?

 

[Renegade_8]

As you open the throttle the mixture will richen and so burn quicker. The engine will be mapped to alow for this and prolly this is why it stops knocking. It might be worth checking the plumbing of any manifold vacumn sense lines. Im surprised a modern engine needs decoking at all, i ran my old 1.6BX petrol round to 250K miles and apart from routine maintenace it never had a spanner on the engine.