1.7.9 Operation readiness of the rear HO2S
The operation readiness diagnostic of the rear HO2S runs continuously and can detect faulty electrical connections. Heater circuit faults are monitored separately. Most of the checks use the measured voltage of the rear HO2S as an input for diagnosis. (Scheme 26) indicates the regions on the voltage versus normalized A/F ratio characteristic curve where malfunctions are detected.
Scheme 26
1.9.1 General description of the PCV-System
Blowby gas with oil reaches the cylinder head cover, where the oil will be separated and directed back to the oil sump. The cleaned blowby gases are directed via the intake system to the combustion. The pressure regulator makes sure that the high vacuum level between crankcase and ambient air will be reduced if needed.
1.13.2.1 Monitoring overview
The electronic control of the Variable Valve Lift (VVL) is dependant on, Voltage Limits, Adaptations, current and power stage temperature. The following errors will be detected in this system.
Variable Valve Lift Electrical Diagram
Scheme 27
1.13.3 Monitoring overview - VVL sensor diagnosis
Sensor diagnosis is performed internally to the VVL-ECU and checks the sensor supply voltage to tunable boundaries. A sensor signal versus an internal sensor self check will determine the integrity of the sensor.
1.13.8 Monitoring overview - overload protection
P1075, P1076, P1077, P1078, P1079, P1080, P1081, P1082
DC Motor current, control unit temperature and DC Motor overload is monitored through the ECU. This diagnosis checks for over-temperature and short term/long term current overload conditions (looks for current spikes over a threshold, and time vs. current table based).
Error Symptoms
There are two thresholds (warning and critical) to be distinguished for each diagnosis function.
| Warning thresholds | |
|---|---|
| VVL control unit temperature > 105 °C | P1076, P1080 |
| Calculated DC-motor temperature > level 1 | P1077, P1081 |
| Internal modeled electrical load value> level 1 critical threshold | P1078, P1082 |
| VVL control unit temperature > 163° for 400 ms or | P1075, P1079 |
| Calculated DC-motor temperature > level 2 or | |
| Internal modeled electrical load value> level 2 | |
WARNING THRESHOLDS CHART
1.13.9.1 Description and diagnosis of this module
If a malfunction of one of the valvetronic components is detected, the management tries to drive both actuators to their end positions (limp-home = full valve lift). In this case, the charge control will be managed by the throttle. If one actuator cannot reach its end position, the valvetronic tries to ensure, that the load on both banks reaches a common level. Any reduction of valve lift will lead to a reduction of the engine power. A DTC is stored, if one of both actuators was not able to reach its end position.
There will be a distinction, whether this error was detected directly by a comparison with the actuator angle or indirectly by checking the engine roughness or comparison of load or comparison of air mass flow. This balance test is carried out for thermal protection of the catalyst. If the air charge distribution on both cylinder-banks is unequal, the fuel system runs a danger of delivering an incombustible mixture.
Error Symptoms
| Valvetronic malfunction was detected and limp home mode is set. There is no information about the actuator's end position and the engine roughness is detected as too high. | P1061 |
|---|---|
| Valvetronic malfunction was detected, limp home mode is set, one of the actuators didn't reach its end position (sensor position available) and actuator angle < 150°. | P1062 |
| Valvetronic malfunction was detected and limp home mode is set. There is no information about the actuator's end position and the comparison of full load with an internal characteristic value is detected as too low or the comparison of measured air mass flow and calculated air mass flow through the throttle valve in the complete engine is detected as too high. | P1063 |
ERROR SYMPTOMS CHART
1.15.16.2 Diagnosis during warm operation
During warm operation it is checked whether there is a permanent deviation between the current idle speed and the setpoint idle speed. Additionally it is necessary to take into account the condition of the ISC integrator.
The ISC integrator is a measurement for the regulated deviation to reach the setpoint idle speed and is limited to an upper and lower limit.
If the throttle valve opens too much it may happen that the idle speed rises above the fuel cut-off engine speed and the system starts oscillating. To cover this special case the number of detected fuel cut-offs during an idle phase is analyzed.
If...
- the deviation (positive) between setpoint and current idle speed (under speed) exceeds a calibrated threshold and
- the ISC integrator equals the upper threshold limit and
- no active fault of air mass sensor
- the engine load lies below a calibrated threshold
- all for a calibrated period of time, a minimum fault LLR will be set
If the deviation (negative) between setpoint and current idle speed (over speed) lies below a calibrated threshold and the ISC integrator equals the lower threshold limit and no fuel cut-off condition has been detected, all for a calibrated period of time, then the lower minimum integrator threshold limit is extended for further investigation.
If...
- the deviation (negative) of the current engine idle speed lies below a calibrated threshold and
- the ISC integrator equals the lower threshold limit or the ISC integrator has reached the system demanded limit and
- still no fuel cut-off condition has been detected
all for a calibrated period of time, a maximum fault LLR will be set.
If the number of detected fuel cut-offs during this idle phase exceeds a calibrated threshold for a calibrated period of time, a maximum fault LLR will be set.