missfireing when cold

[jamo]

i have a wrx wagon l reg and have and intermitant problem with it missfiring badly when cold,this problem goes away when engine is hot and only happens about 50% of the time on cold starts.vehicle has no loss of coolent or oil and i have changed the plugs approx 3 months ago and have fitted new coil packs last week.i have also tryed another air flow meter to no avail,so am a bit unshore what to try next (car doesnt miss a beat when warmed up)

[The Daddy]

try decreasing the plug gap......90% sure this will cure it......

What plugs are you running? and are you running 97+ octane fuel???

[jamo]

running ngk xtreams (iridum) with scoobie ecu set for optimax (on optimax) what gap setting would you use 0.5mm?(i think 0.9mm is standard?)

[The Daddy]

0.5 would do it...

[scoobymat]

Standered plug gap is 0.7mm, not to be down beat or anything have also heard irridium plugs aren't as good for scoobies as platnium are:frown:

[scoobyDAZZA]

try some ngkpfrb6 or the 7s if its modified,
set to 0.6mm

[The Daddy]

i run iridiums mainly for the fact that the nitrous heat can cause the platinum tips to drop off in the engine...........

ngk 7s are great for a modded engine......when i had my miss fire power engineering regapped the plugs to .5mm and it cured it.....

the misssfire was down to octane booster coating the plugs in lead and causing tracking........

[scoobyDAZZA]

i used to use quite alot of OB and had to change the plugs every 3000mile / 6 months . . . i've gone a bit steady now on the old booster and they're lasting alot longer , , only use OB now for ''certain days'' ;)

[Neil G]

Changing the plugs every six months:eek:

[jamo]

cheers to everyone for advice have dropped the plug gap to 5mm and now the missfire has all but gone!