No valves seem to break after the software is upgraded and the rovers didnt have this trouble with exactly the same manifold so I reckon there must be something to it.

ianda12 said:

No valves seem to break after the software is upgraded and the rovers didnt have this trouble with exactly the same manifold so I reckon there must be something to it.

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MG and Rover KV6 plenums fail too. It's not a software issue, it's a quality issue. These plenums were made in Germany down to a price. They are c**p period.
The MG ZT 180 used the same engine, gearbox and ECU as the Freelander. Those plenums break just as often as all the other KV6 variants.
If you consider what that little plastic ball joint has to do, it's no wonder it fails. The engine is always sucking on it, the whole time it's under 4000 rpm. This will make it rattle about, after a while the slop in the ball joint gets so large that the valves chatter. Eventually the ball and socket part company allowing the valve to open and close as the engine sucks on it.
I believe that engines that never really get over 4000 cause the power valves to fail earlier then those engines that do get over 4000 quite often. This is because the more time the valve is open, the less influence the engine's breathing has on the valves. It can't suck on it as it not obstructing the air passage.
I've spent years working on these things. They are a good idea badly made, nothing more complex than that.