The 1980 USA version 450's were the first Benz's with Lamda controls. O2 sensor & frequency valve to control mixture. The injector that is on the drivers side of the air flow housing should be "buzzing" any time that the engine is running. IF not then check the overvoltage protection relay! ON that car the relay is a 1 time event(no replaceable fuse).

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MERCEDES Benz Master Guild Technician (6 TIMES)
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