what is the causes of det

I have a rebuilt STi 5 engine with cossie pistons, steel rods, up-rated oil and fuel pumps, fuel reg, magnacore leads, water injection. Running standard turbo, injectors, air filter, dump valve. car is GEMS mapped. THe car was previously running perfect at 1.6 bar.

Car was off the road for 6 months after which knock is showning on the at 4k revs.

oil has been changed, fuel clean with octane.

I have checked over everything and cannot find anything obvious. It has been suggested that the bores have glazed due to the car being stopped and started for short periods-cold. But i dont buy that one.

Any comments gratefully received.

cheers
za

acmitchell@jamesbarr.co.uk

 

Have the new pistons raised the compression ratio?

If it is higher you'll need to remap it to compensate, as it will det at that level of boost.