Need need some advice......
Im having issues of poor mpg, i was getting 35-38 mpg and recently im getting 23-24 mpg doing same distance/driving. I did have a leaking filler neck.now replaced, changed cts for another gm one, been on opcom no fault codes and lambda sensor looks ok. Only thing i notice with the readings on opcom the mixture always says rich never says lean even when u drive or rev it?? Had plugs out they're blacked up! New set in after bit a driving they going black!! No blow on exhaust and even replaced the manifold. Car always ran on optimax. Im at a loss atm