Engine misfire no 3

ok not my 197 but my daughters mk3 1.2 has a misfire on no3 cylinder. I checked it and one plug was showing signs of water in the plug hole but it was dry. So I replaced coil pack and leads and plugs but it's still the same. P0300 and p0303 . I think it may be an injector but open to theories !!
 
is it only at low revs?

put a new plug in the end of the lead to see if theres a spark?

compression test?

check voltage down the injector multi plug
 
It's when idling you can hear it popping through exhaust, mil flashes at same time it runs rough. Won't pull up hills. I will try to check injector voltage but the inlet manifold is in way so Would need to remove it.
 
It's when idling you can hear it popping through exhaust, mil flashes at same time it runs rough. Won't pull up hills. I will try to check injector voltage but the inlet manifold is in way so Would need to remove it.

poping - usually a burnt out valve - check valve clearances?
 
It's intermittent so farely sure not that. It's not tappy so don't think it's a lifter. She does run it low on fuel though so maybe crap in injector. I could swap two and see if fault code changes. If I need another one do they need coding like diesel ones?
poping - usually a burnt out valve - check valve clearances?
 
It's intermittent so farely sure not that. It's not tappy so don't think it's a lifter. She does run it low on fuel though so maybe crap in injector. I could swap two and see if fault code changes. If I need another one do they need coding like diesel ones?

nope just remove & fit new
 
Ok thanks for your help. Will try an injector then failing that compression test. I have just noticed tho it's low on coolant! I don't think they suffer headgaskets but might be the issue

didnt see many at work with h/g issues....but did with burnt out valves...