Thanks very much for the response. I have a DVM with duty cycle function. As I have understood, the duty cycle indicates the fuel/air ratio.
Additionally, mine is an '88 model. Bosch provides fault code error trapping within the controller for the KE3 Jettronic. I can't imagine them removing the fault code trapping for MB's use of the unit. There must be a way to retrieve these codes. I'm sure that the dealer has some way even if it is their expensive diagnostic system. Most every car with fault code trapping has a means of retrieving the codes without the use of the expensive system owned by the dealer. Thanks again for the response.
Have a great day,
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in