This last Friday I made an attempt to tune my car for E85. The problem is that with 93 and E85 the car is still seeing knock. What I would like to know is what are the mechanical causes of knock retard? We have backed down the timing and the car still continues to see knock. It probably doesn't help the the MAF calibrations are way off but I am looking to see if I have possibly caused internal damage with the previous tune. Any help would be much appreciated.