Jovan Caro

so I have a evo8 when I do a cold start the engine revs up to like 800 and I look a my wideband and it sits at 14.9 for a couple seconds then goes all the way to 11 for about 4 seconds then goes to 16-17 for 20 seconds then when the engine is on for about a minute goes to 14.6-15.5 and revs at 1k not sure what's going on

Jovan Caro

Here's a pic of my plug they all look like this. At cruising speeds I'm at 14.6 to 15.5 at 3k rpm idk if that's good or bad

Ferp

AFRs are always a little different on cold starts. My car will stay in the 11-12.5 range for quite a while on -30 day cold starts. The engine is trying to warm up so it's going to burn more fuel to do so. Between 14.5-15.5 cruising afr is totally normal.