I'm not very familiar with the non-lamda systems, but I do recall seeing some information in the service literature about adjusting non-lambda systems (which also means no catalyst) to a specified CO range, which is considerably higher than the lambda/catalyst systems CO range.

On the non-lambda systems the EHA probably only controls cold start enrichment. Once the engine is warmed up the mixture is controlled purely by air flow plate deflection just like the older K-Jetronic systems.

Bottom line is that there is a big difference in lambda and non-lambda systems and each should be adjusted IAW the applicable Mercedes service infromation.

Duke