Scheme 1
| Type | 6-cylinder aluminium opposed-cylinder engine, water-cooled | |
|---|---|---|
| Bore / stroke | Mm | 85,5 / 72 |
| Displacement (actual) | Cm 3 | 2480 |
| Compression ratio | 11,0: 1 | |
| Max. engine powe | KW/PS | 150/204 |
| At engine speed | Rpm | 6000 |
| Max. torque | Nm | 245 |
| At engine speed | Rpm | 4500 |
| Engine control | Bosch M5.2 with static high-voltage distribution, sequential injection, cylinder-specific knock control, stereo oxygen-sensor control and diagnostic system. | |
| Cylinder head | 2 overhead camshafts with hydraulic valve clearance compensation | |
| Camshaft drive | Porsche VarioCam | |
| Type of fuel | 98 premium unleaded | |
ENGINE SPECIFICATIONS
Scheme 2
Scheme 3
Scheme 4
ABS operation
The ABS control unit receives a signal from the brake-light switch and the AC voltage signals from the four speed sensors. These signals are converted into digital wheel-speed signals independently of each other by two microprocessors. The wheel slip (approximately proportional to the computed vehicle reference speed) is formed from these wheel-speed signals.
If vehicle deceleration and excess slip are detected at a wheel, the pressure-holding phase is initiated, i.e. the inlet valve for the relevant wheel is closed to prevent a further increase in pressure. If in spite of the pressure being held constant the wheel tends to continue to lock up, the pressure in the wheel cylinder is reduced. For this purpose, the outlet valve is opened and the brake fluid is pumped back to the brake master cylinder via the return pump (pressure-reduction phase) until the wheel turns again. Then, depending on the control cycle, further appropriate cycles are initiated.
This function and the input signals are continuously monitored. If a fault is detected, the control unit switches the ABS function off, switches on the ABS warning light and stores the fault in a non-volatile memory in the control unit.
In addition, whenever a journey is begun and a speed of 6 km/h is exceeded, a test programme is started. The solenoid valves and the pump motor are electrically actuated and checked. If a fault is detected, the control unit switches the ABS function off, the ABS warning light is switched on and the fault is stored.
Scheme 5
- ABS control unit, hydraulic unit, pump-motor relay and valve relay form a unit that is located next to the brake master cylinder.
- Brake unit (brake booster with tandem brake master cylinder)
- ABS hydraulic unit * (3 hydraulic outputs)
- ABS speed sensor
- Central Information System
- Brake proportioning valve (1x)
- Brake light
- Brake-light switch
- ABS warning light (yellow) Front-axle braking circuit Rear-axle braking circuit Handbrake cable deflection box
ABS / TC 5.3 (4-channel system) system description
Note. Traction Control (TC) represents an extension of the ABS system and is a combination of anti-slip control (ASR) and Automatic Brake Differential (ABD).
Operation
Driving stability control
If Traction Control (TC) detects that a certain speed difference between the wheels has been exceeded (wheel spin), engine power is automatically reduced.
Brake control: In addition to reducing the engine power (driving stability control), the TC (via the ABD) brakes the drive wheel that is spinning.
Since this control requires the drive wheels to be individually controlled, the ABS/TC system is a 4-channel system.