Remove the bolts that hold the exhaust heat shield in place so it can be slid toward the engine giving better access. Use a 17mm crows foot wrench on a ratchet extension to loosen the lock nut. Use a dime to turn the adjusting screw. It's still a tight squeeze but this will keep you from having to lift the engine. Note: mentally visualize the position of the adjusting screw before loosening the lock nut. Put the dime in and picture one o'clock, three o'clock or whatever it is.