Test Group YBMXT04.4E53, YBMXT04.453M, YBMXV04.4LEV & YBMXV05.4LEV
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2000 BMW Z8, 2000 BMW Z3, 2000 BMW X5, 2000 BMW M5, and 2000 BMW M Roadster. However, it is still accessible from the selected car via links, so may be relevant.
- Fuel System Monitoring General Description -
Fuel system monitoring includes lambda controller restriction against limits for rich and lean and permanent deviation from mean position:
- Mixture Pilot Control - The air mass taken in by the engine and the engine speed are measured. These signals are used to calculate an injection signal. This mixture pilot control follows fast load and speed changes.
- Lambda-Controller - The ECM-controller compares the oxygen sensor signal of the sensor upstream the catalyst with a reference value and calculates a correction factor for the pilot control.
- Fuel System Monitoring Structure -
Fuel system monitoring consists of following:
- Adaptive Pilot Control - Drifts and faults in sensors and actuators of the fuel delivery system as well as not measured air leakage influence the pilot control. This causes increasing deviations of the air/fuel ratio. The adaptive pilot control effects the controller on in three different ranges. See Fig 1.
- Ranges Of Learning Correction Coefficients TRA, FRA And DTV - Lambda deviations in range 1 are compensated by an additive correction value multiplied by an engine speed term. By this, an additive correction per time unit is created. Lambda deviations in range 2 are compensated by a multiplication factor. Lambda deviations in range 3 are compensated by an additive correction per injection. A combination of all three ranges will be correctly separated and compensated. Each value is adapted in its corresponding range only. But each adaptive value corrects the pilot control within the whole load/speed range. At the next start the stored adaptive values are included in the calculation of the pilot control just before the closed loop control becomes active. See Fig 2.
- Fuel Delivery System Abbreviations -
Fuel delivery system abbreviations are as follows:
- QU 1 - Upper air flow threshold range 1
- NU 1 - Upper engine speed threshold range 1
- TLARN - Upper engine load threshold f(n) range 2
- TLL2 - Lower engine load threshold range 2
- TRA - Additive per time unit learning correction coefficient (range 1)
- TRADN - Lower diagnosis threshold of TRA
- TRADX - Upper diagnosis threshold of TRA
- FRA - Multiplicative learning correction coefficient (range 2)
- FRADN - Lower diagnosis threshold of FRA
- FRADX - Lower diagnosis threshold of FRA
- DTV - Additive per revolution learning correction coefficient (range 3)
- DTVDN - Lower diagnosis threshold of DTV
- DTVDX - Upper diagnosis threshold of DTV
- QL2 - Lower air flow threshold range 2
- QU3 - Upper air flow threshold range 3
- NL3 - Lower engine speed threshold range 3
- TLL3 - Lower engine load threshold range 3
- Diagnosis Of Fuel Delivery System - Faults in the fuel delivery system can occur which cannot be compensated for by the adaptive pilot control. In this case the adaptive values leave a predetermined range. If the adaptive value is outside a plausible range, then the MIL is illuminated and the fault is stored. See Fig 3.