2015 STI engine knock

[stubbsey]

My up-graded 2015 STI has suddenly developed a knock on tick over only - disappears at 1200 rpm. Everything else is fine, no change to performance or power.

Any ideas please?

Thanks

[vxr2010]

you said upgraded , has it got forged pistons ? is it crank or piston related , if it’s not forged it’s concerning , but if it is forged then the noise is there all the time especially when cold , it could be ring land failure starting , is it using oil ? worth a bore scope they are about 80£ , i would not drive it until you know what the issue is or you could ruin your block too

[stubbsey]

Everything forged yes and closed deck block.

The noise is only there on tick over and goes at approx 1200 revs

[vxr2010]

and it’s only just started doing it , or you have only just noticed it , can you describe the noise , a forged piston when cold can rattle a bit till it expands then it goes quieter but can still make more noise than a standard piston , or you can get a pit of piston slap too when it’s cold , how long ago was it forged ? worth asking who forged it too