We've been tuning our car for years (with limited success) using the data retrieved directly from an M48 using the DOS ECU program in the belief that this was the most "pure" representation of the fuel mapping. This past weekend we just happened to retrieve it from the ADL dash Manager for comparison. To our surprise, the data was quite different! While the DOS ECU data showed Lambda values within acceptable ranges, the ADL Dash Manager Lambda values showed significant variations outside the normal range that coincided with the "stumbling" I was experiencing with the car's engine. For the first time ever, we decided to make fuel adjustments based upon the ADL Lambda values rather than the DOS ECU Lambda values. The results were surprising in that they corrected our problems more effectively than ever before!
Does anyone know why the DOS-retrieved data might be invalid?