[jamesm]

Originally Posted by arghx7

I know you're not the OP but I'm going to address your posts because it is still relevant. I downloaded your logs and made some plots.

Top chart shows engine rpm in blue, knock retard events in red. Bottom chart shows vehicle speed kph in black and IAM scaled up where 100=1.0

I'm going to throw something out there. I think in some cases you're getting LSPI. Considering the nature of LSPI it's not going to happen on every detected knock event, but the fact that you are hearing "ball bearings on a marble floor" sometimes is a big sign that this isn't always false events.

What the heck is LSPI? It stands for Low Speed Pre Ignition also known as Super Knock or Mega Knock. It's not very well known in the aftermarket. It sounds scary, and it kind of is. It's what can happen when a turbo engine spools up at low rpm, especially turbo DI engines. It usually happens at 2500rpm or less, especially under 2000rpm. You don't commonly hear about it because DI engines with factory turbos are tuned to stay out of the "no man's land."

Usually an LSPI event will hit peak cylinder pressures of 140-190bar, similar to a diesel. Your pressure rate of gets very very high. That's where the noise comes from. It's different from regular old knock or preignition from hot spark plugs and such. There's basically no simple solution for it, and it's somewhat random. Pulling timing often doesn't solve it, although a richer mixture can help sometimes. Theories for its causes abound and I won't dive into them here.

So basically, if you're actually hearing a loud "marbles in a can" sound at low speed tip-in, and some simple spark retard is not working, you have limited options to solve it... there are guys with PhD's who have been trying to figure it out for years. I'm not trying to sensationalize anything--you probably make it go away with enough fuel and spark retard. It's important to recognize though that this problem exists and if you really do have it there isn't an easy solution.

well that's no fun. does it help that my knock usually occurs when the car is still in vacuum?