My 03 Sti seems to have symptoms of a misfire when accelerating on half throttle. Put new plugs in and had it plugged in no faults. The problem is worse when cold. If you full throttle its like one misfire then fine.
Can coil packs cause this or do they tend to just pack up straight away?

 

my wrx was the same ,,one of my coilpacks was broke ,,so yes it could be the packs

 

Would the problem be worse when cold then?
Wasn't sure if they went they went or slowly broke down.
Would it not show up as a fault in ecu? It is very intermittent though at minute.

 

mine was missing bad when cold on acceleration then a bit better as car got up to temp ,,
i did the plugs and it was same then changed 2 packs could hear a clicking sound down pasinger side of engine and it run right
one of mine was cracked and the end fell off

 

I will check them then. Sometimes though it seem like its bit hesitant rather than a misfire so could be a maf problem aswell I suppose. I might get it dyno run to see before I throw parts at it I'm sure they will be able to tell.

 

thats wot mine was like ,,its best if you take it to a garge that knows about scoobys
you could end up trying all the bits and it be the last one you buy
some one els will give you some more advice on here

 

It's more hesitant I've noticed when your turning obviously putting load on engine.

 

It could also one of the HT leads breaking down and tracking to earth, its well worth checking under the bonnet with the engine running and in the pitch black of night. You may be able to see the tracking and locate your problem if its leads or coilpack or eliminate them from your list of suspects.

 

Just spoke to local Subaru dealer and he says my symptoms sound like maf sensor.