the car has run fine for 2 months in and out of the workshop - left idleing for an hour at a time sometimes, nothing changed until it ran out of fuel
didn't think knock had anything to do with idle but been a long long time since i got involved with g40 stuff, mainly 1.8T and tfsi these days
i went to rev it, it bogged then i booted it to the limiter then it bogged and sputtered ( had no dash at the time so was unaware of low fuel) nursed it back into the workshop - threw £2 of fuel in and fired straight up