On any car that has adjustment for fuel, the mixture can be adjusted TOO much(rich OR lean)! Then the computer imput from the O2 sensor won't allow any fuel mixture changes!!
AT this point the car could run better but most likely worse!
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)