Det Problem - Getting Desperate...

[CabbageMS]

Hey all,

Ok I have a 1991 R32 GTR. It has detonated since i picked it up in UK. It is unmodified except for a decat pipe. It has detonation. Looking at the pistons, 4 is pitted and 6 is mildly pitted. When I changed to denso plugs 4th cylinder took a tip off.

Important info:

• It runs factory boost with restrictor.
  
• Brand new coil packs (standard)
  
• A/F ratio about 11/1 full boost (measured with innovate wideband LC-1.
  
• Ignition timing set to 20o BTDC using HT lead between coil pack and plug on first cylinder
  
• New cambelt
  
• Completely unmodified engine
  
• Cleaned and flowed fuel injectors
  
• Fuel pressure tested and Ok.
  
• Manifold checked and not leaking
  
• boost around 6-7 psi.
  
• stock ecu, unchipped.
  
• new ignition amp (standard)
  
• Fuelled on super unleaded.
  

Any ideas???

[MrStabby]

What plugs? What's the octane rating of the fuel? 95RON is absolute minimum.