When an injector sticks open its usually through a defect in the injector and it'll stick open early in it's life. When RC balances the injectors they operate them... if an injector has a defect that'll cause it to stick open it'll happen when they're balancing them 95% of the time. You'll still have to replace the injector, but you'll find out before you install it on your Z...and potentially damage your Z from it.