So this is the story as far 2002 WRX with a blown engine, so I've fitted a 2002 STI engine with AVCS done the wiring mod and fitted the STI ecu, start and runs ok but the idle seems rough and brings on the EML, and fault code says its a miss fire on cylinder 3 and 4.

So I've pulled the plugs off the coil packs whilst running and pull 4 off idle is much worse pull 3 off and changes a bit. I've swapped the coil packs around and no difference, changed the plugs no difference and I've checked the wiring to the coil pack 12v + 12v - and 12v - trigger all fine. But the con fussing thing for me so far it she makes boost with no stutter at all but stalls on over run so I'm think maybe MAF or maybe a burnt valve I've got to do a compression test but I'm still heading towards electrics any body have any ideas?

Cheers Andy

 

So cleaned the MAF no difference cleared the fault codes and tried again only fault is missing cylinder 2. Did a compression test and guess what no compression . So is it valve piston or gasket ? I put the cylinder to TDC and made an adapter so I could put my air line onto the cylinder to tell what was happening be for I pull the engine

1 no air coming in to water no bubble so gasket fine
2 no air coming from exhaust
3 no air coming from crank case so piston/rings look intact
4 air coming from throttle body

So it looks like a burn inlet valve so fingers crossed and easy fix

Cheers Andy