Only the first 190s had adjustable idle speed. The amount of air entering the engine is what controls engine speed. The allen adjustment at the fuel distributor does mixture.

To start the diagnostic at the passenger side connector use the code retrieval initiation of a two second grounding impulse to hole number 3. Go to the DIY article about evaluating engine controls for more precise discussion of the diagnostic trigger.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician