Dansvan

The cylinder misfiring had no bent valves.

Back of the V? Can you explain that please?

I was under the impression the injectors shared a common power source and the computer provided the ground to fire them? But ive been wrong before

FredR

If you had a consistent leakdown of 3% I doubt very much you would get such a reading with a damaged valve- such values are those of a healthy engine or so I would think.

At the back of the Vee and underneath the plumbing there are two earth points with multiple connections- they are hard to get to with the inlet manifold in situ but like any other earth connection they need to be cleaned from time to time and of course securely fastened. If integrity of those earth connections is lost then there may well be issues.

Our friend in the comment you refer is a tad "confused" in that the earth connections from the fuel injectors do not go through those earth terminals - they come together into one cable that passes through the LH computer where [as you correctly understand] the signal is switched to earth to fire the injectors. Needless to say if there is a fault between the injector and the earth return to the LH computer the injector will not fire correctly.