Test Group XBMXV02.8M52, XBMXV02.8LEV & XBMXV02.5M52

WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1999 BMW Z3, 1999 BMW M3, 1999 BMW M Roadster, 1999 BMW M Coupe, and 1999 BMW 750iL. However, it is still accessible from the selected car via links, so may be relevant.

General Description - Fuel system monitoring includes lambda controller restriction against limits for rich and lean and permanent deviation from mean position.

Monitoring Structure - If fuel system is suddenly hard disturbed (for example: by a leaky injection valve) and therefore lambda controller reaches restriction (lean limit), a timer is started. Timer is incriminated as long as controller remains at limit. If timer exceeds a predetermined value, a fault for short trim will be detected and stored. For permanent deviation from mean position, there are additional lean and rich thresholds. If accumulated time (sum of all excesses for rich and lean) is greater than a fixed limit during a defined period, a fault for long term trim will be detected and stored. See Fig 1.

Fig 1: Fuel System Monitoring Conditions

Courtesy of BMW OF NORTH AMERICA, INC.