More than 12 months after IVA I’ve now finally sorted out the problem that was giving me Engine hesitation in 1st and 2nd gears on my LS6.
When I wired up the Engine loom I’d wired the clutch pedal position to positive in order to get the engine to start. I’d read on the internet that it was required because US cars don’t start unless you are depressing the clutch.
As it turns out you don’t actually need this connected at all. Car started fine without the CPP connected at all and now does note hesitate at all.
Massive extra power now in all gears. Scarily quick. Hypothesis is that this was either affecting the spark tables or affecting something else in the PCM. Either way – Just glad to get it sorted. Many thanks for all the help in sorting this (especially Paul Spinks, Jim Thompson, , Martin at Marlin Cars, Meena and Andy).