2.5 Lean Conditions
I have error codes 21 (O2 Sensor Circuit) and 51 (Lean Conditions Detected). I did have 14 too (MAP Sensor), but a new MAP sensor made that code go away. SO doing some research on lean condition I saw people saying things like you could do some serious damge like burning holes in pistons and things. I am assuming I have to replace my downstream O2 sensor and all will be fine. I have driven it probably 200 miles, and about 3 hours on the trails since this started. I know some people lean on their carbs on purpose. I am just curious if I might have done any damage, or how serious of a problem this could be. I am also kinda surprised because I cahanged my O2 sensor about a year ago. When it went bad last time I did not get error code 51, only 21. Any help with this would be great before I go spending more money.
Complete rebuild axle/engine/everything swap in progress: Building stock width 44's with 302 from 01 Explorer. Motor has GT40p heads, Cobra Intake, and truck cam. Running A9L EEC IV stand alone engine from late 80's-90's Mustang GT. Big Bearing NP435 married to NP205.