I've got a 2.0 converted Si.
It seems to have developed a really rough idle. it was never perfect, but recently it seems to have got worse.
Today i've had ISCV off and given it a clean. tried different ECU, different MAF. put different TPS on it.
anyone got any other ideas?

 

leads and plugs ok?

ISCVs need to be cleaned when they've been taken apart (well, the two halves separated anyway). Otherwise they just stay stuck when they're being cleaned, all you end up with is a shiny air tunnel

 

What sort of rough idle?

Surging?

 

sometimes it will idle fine, then it just starts chugging all of a sudden.
occasional miss when cold too.
runs fine other than this though.

thinking maybe cracnk breather hose, or, lambda, but not sure if lambda is used at idle

 

could have developed an air leak somwhere possibly aswell.

 

if the weather ever clears i'll have a proper gander at it.
getting a touch annoying, it's worse when cold