Traction Control

TRACTION CONTROL (TC):
Function:
While the engine is running, the DME control unit calculates the actual engine torque from the following variables: engine load signal (TL), current ignition angle, and engine speed (n).

If the TC control unit detects that the wheel slip for the rear axle of the vehicle is too great, the TC control unit generates a signal which is sent as a nominal engine torque to the DME control unit via the data cable in the form of a pulse-width modulated duty factor.

If, when the nominal engine torque (from the TC control unit) is compared with the actual engine torque (calculated in the DME control unit), a deviation is detected (rear axis has too much slippage), the DME control unit reduces the engine torque by disabling injection and adjusting the ignition angle towards "late" until the nominal engine torque and actual engine torque are identical (the rear axle no longer spins). Activation of the TC function (reduction of the torque by the DME control unit) is indicated by a green lamp in the instrument cluster.

If the TC control unit requests a reduction in torque which requires the disabling of individual cylinders, the appropriate injection pulses for the cylinders to be disabled are completely suppressed (injection valve is closed). An injection pulse which has already begun will always be completed despite the TC requests. If a cylinder is released within the corresponding injection period, the remaining injection period is not completed.

Two disabling patterns which permit up to 12 reduction steps are processed within the DME control unit. The disabling pattern changes after 6 calculated injection pulses.

However, a "stall protection" feature is also programmed. This prevents the torque from dropping below a specific engine speed (1,200 rpm).

Disabling of the corresponding cylinders occurs alternately and corresponds to the injection sequence.

When the individual injections are restored, a factor is added to the respective injection signal. This factor is based on the current operational status of the engine and ensures that, after a cylinder has been disabled (temperature drop, etc.), it receives an optimum air/fuel mixture required for combustion.