Other air request
| Other air request |
| Idle speed control |
When the accelerator is fully released and vehicle speed is zero, the system regulates the mass air flow/combustion required to ensure that the current idling speed corresponds to that requested. The air requirement is stored in the control module's memory (adaptation). The requested idling speed is stored in a table in the control module's memory and is dependent on the temperature of the coolant
At -30°C, idling speed is 1200 rpm and as the engine warms up the requested speed is reduced to 825 rpm.
The TCM sends out the information "Selector lever position”, unit P, R, N, D, 3, 2 or 1, on the bus to the Trionic T7.
When any value other than P or N is selected, the requested mass air flow/combustion is increased to compensate for the impending load increase. The purpose of this is to compensate fully for the automatic transmission's increased torque requirement to avoid a sudden drop in idling speed before the idle sp eed control can compensate for this. The air requirement in any position other than P or N is stored in the control module's memory (adaptation).
As soon as the car begins to move, the idle speed control is disabled and the engine receives the adapted air quantity.
| Diagnostics |
Information on the difference between requested idling speed and current speed, and whether the idle speed control is active or not, can be obtained using the diagnostic tool.
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