MumBleZ_94gsR

what does this white corrosion on my exhaust valves mean? to rich, lean, or wat?

BigBlock22

lean ... do you have any check engine lights on? sometimes things like faulty o2 sensors or malfunctioning EGR can cause your engine to run lean (hotter).

MumBleZ_94gsR

no CEL's but i need to send my ecu to get chipped cuz i just rebuilt my engine with and ill be running high compression... i only have 173 miles on it ...im in the process of breaking it in

BigBlock22

ok... normally exhaust valves are a lighter color due to them getting more heat to them unlike the intake valve which gets cooled off from incoming intake air. it is normal for the exhaust valves to have a tan or grayish color but if your plugs are having the same problem then look into having the exhaust valve lash ( jam nut adjusted properly) set to its right spec. not running a tuned computer on a new setup is not a good idea. i would stop driving the car until you can get a hold of a wide band o2 and a fuel controller. you probably just need to have the air fuel ratio corrected.

BigBlock22

also... running a higher compression piston will raise the combustion temperature, causing the ex valve to look that color especially on a stock computer. it will definitely throw off o2 readings. once again, get it tuned