I've recently fitted a BBM manifold to my ED XR6. I am running a MS1 ECU controlling both fuel and spark.

Before fitting the BBM I was running around 30deg Ignition advance from 2500rpm. Now with the BBM I have had to drop this to 15deg between 2500-3800rpm otherwise it pings.

I know the BBM requires different ignition timing on the long runners, but 15deg max advance seems very low. If I force the manifold to short runners I can run full advance without any problems.

Has anyone else experienced this when tuning with the BBM? What could be causing this problem?