ChipperOne

I haven't dug around too hard looking for this, so flame away if it is in a FAQ, but...

Should a different temp (or at least gap) plug be used in a chipped S4? I'd think all of that extra boost would need a cooler plug. Or does the ECU somehow compensate for that with timing?

-- Chipper

Ferris TMK

I wouldn't go a different temp, unless you do mostly long high way drives. If you do want to go colder only go one step colder. As far as the gap, I did a write up a while ago with instructions on how to change the plugs, unfortunatly the search is not cool and I can't find it. I went with Iridium plugs, since the resistance is less you could have a factory gap with less chance of weak sparks or misfires in the higher compression enviroment. Copper is the best choice since the resistance is the smallest, but it's lower tensile strength means you will need to change them more often. If you stick with the factory platinums you may want to re gap them smaller, if you notice hesitations or misfires. I have tons more info, if you want ask a question and I'll answer =)

VonK :: Retired

.... such as platinum or iridium primarily chosen to combat erosion, thus allowing them to operate over a wider temperature range?

Isn't the spark circuitry (CD) optimized for a specific plug's impedance (conductivity and gap)? Therefore, wouldn't any other plug, or merely a changed gap, degrade performance?