There are several reasons why you may or may not want to use lambda.
1. Using a narrow band lambda sensor which is used on most early emissions cars is only suitable for fine trimming the fuel whenever everything is set up correctly. It is not a device to try and fix poor idling or poor running. It must be running correctly before lambda is used.
2. If your car does not require lambda or run tight emissions control, then don’t use the sensor it only adds to the complexity. All our systems are designed to automatically disable lambda control if the lambda sensor is not seen.
3. If you wish to use lambda as a mapping aid, then you would need to use a wide band lambda sensor and the 9A4 and 9A8 ECUs would need the use of a lambda controller. Something like an Innovate LC2 system or similar. These produce an output of 0-5v, the ECU can then be calibrated based on the Innovate information to convert this voltage into lambda. You would then use this information when mapping to ensure the fuel mixture is correct at the speed and loads. It is even possible to set up the ECU to do closed loop mapping, but this is something for the more advanced user.
If you are going to have the engine programmed professionally on the rolling road, it is always best to take advice from the expert that you are confident to deal with. Every rolling road and dyno has their own way of doing things. If we were to do any programming for you some of this can be done remotely, but we would need to be able to read lambda in the ECU. So we would suggest something such as the Innovate LC2 system should be used. We can calibrate the ECU accordingly then do Team Viewer session to set up idling and low speed running before going to a rolling road and then if you wish us to do some mapping at the rolling road, we can also arrange a time to suit.