Originally Posted by
cobaltssoverbooster
un metered air causes o2 to be drastically lean which makes your trims go high positive. typically the intake gasket goes out and leaks air into both sides which is why both are reading that way.
stock tune the maf isnt active until 4000 rpm so all unplugging it does is removes the iat circuit thats usually in it and forces open loop due to thrown codes which means the trims aren't active. in 200 you might have the canister maf which might not have an internal iat, but either way disconnecting it forces open loop due to triggered codes.