Spectacular Failure!

[jonah 1]

It's obvious as there is only one way a petrol engine can rev with the throttle shut. The throttle wasn't shut. The pedal might not have been down but sure as eggs is eggs the butterfly was jammed open.

Oh c'mon Dave, could you have honestly deduced that from the evidence given?

 

I can think of other ways...

 

-An air leak into the inlet manifold combined with overfuelling for some reason (but too much of a coincidence that it would happen the same time as everything else).

-A piston ring sealing problem (brought on my severe overheating), allowing air from the crankcase into the manifold whenever that inlet valve opens, to be subsequently drawn in by the other cylinders. The breather layout on the Pug would mean that any air drawn in this way would be metered by the AFM and therefore a corresponding amount of fuel injected.

-The coolant system becoming pressurised with air and fuel mixture through the head gasket blow during the WOT overtake, and then when the throttle was closed, the pressure in the cooling system (aided by the coolant boiling due to the overheating problem) forcing that combustible mixture back into the cylinders on each intake stroke.

 

All far-fetched I admit but no more so than the throttle being wedged open by a swollen coolant hose!!!