What color is it? It sounds like he just has a scan tool like the Snap-On Modis or OTC Pegisys. If that is the case, all he is doing is reading information from the OBD-II port. Even if it was a Star-DAS, there is not any fueling adjustments that can be made. He would need software like WinOLS and the DAMOS file for the Bosch ME 2.7/8 and the maps defined to make fueling adjustments.