BMW S85 5.0 V10: Specs, Engine Code, ECU & Maintenance
BMW · Engine information · U.S. & Canada
S85
5.0 V10 · Ten throttles · Naturally aspirated
Ten cylinders and an 8,250 rpm limit define the S85. Its individual throttles and high-pressure VANOS system give the M5 and M6 a distinctly different delivery from a low-speed turbocharged engine.
Architecture
- Engine code
- S85B50
- Layout
- 90° V10 · DOHC · 40 valves
- Construction
- Aluminium crankcase and heads
- Bore × stroke
- 92 × 75.2 mm
- Valve control
- Double VANOS · high-pressure oil circuit
- Speed limit
- 8,250 rpm
Fuel & electronics
- Induction
- Naturally aspirated
- Injection
- Port gasoline injection
- Throttle
- Ten individual butterflies
- Combustion monitoring
- Ion-current monitoring · one unit per bank
- DME supplier
- Siemens
- Controller
- MSS65 / MS_S65
Engine controllers · Siemens MSS65
BMW’s MSS65 manages both five-cylinder banks, synchronizes the ten throttles and controls injection, ignition and VANOS. It also commands the electric oil-scavenging pumps used during cornering and uses ion-current signals for combustion monitoring.
| Controller | Applications & timing | Technical distinction |
|---|---|---|
| MSS65 · SMG | E60 M5 (2006–2010), E63 M6 (2006–2010), E64 M6 (2007–2010) | Coordinates engine torque and throttle blips with the seven-speed SMG. The SMG transmission controller is a separate module. |
| MSS65 · six-speed manual | North American M5/M6 manual applications from model year 2007 | Same DME family with the appropriate manual-transmission software and coding. |
| Power modes | P400 / P500 / P500 Sport, where fitted | Selectable power and throttle-response strategies within MSS65; they are not separate ECU hardware versions. |
MS_S65 is an alternative spelling of MSS65 and should not be confused with the S65 V8 engine. Confirm software, transmission configuration and the BMW part number when replacing or programming a DME.
Selected U.S. & Canadian vehicles
| Model | Chassis | Model years | Engine / factory output |
|---|---|---|---|
| M5 Sedan | E60 | 2006–2010 | S85B50 · 500 hp / 384 lb-ft |
| M6 Coupe | E63 | 2006–2010 | S85B50 · 500 hp / 384 lb-ft |
| M6 Convertible | E64 | 2007–2010 | S85B50 · 500 hp / 384 lb-ft |
U.S./Canadian applications shown. Some early BMW publications round the torque conversion to 383 lb-ft.
Common issues & key risks
Rod-bearing wear. A major S85 concern that can lead to crankshaft damage. Check bearing-service records and discuss condition assessment with an S85 specialist; do not wait for knocking.
Throttle actuators. Gear wear and electronic failure in the two bank actuators cause reduced-power warnings and throttle faults. The engine has ten throttles, controlled by two actuators.
VANOS faults. Solenoid and high-pressure oil-supply problems can cause cam-control faults and poor running. Check oil pressure and the internal supply line; early engines used a line later revised.
Idle & ignition faults. Rough idle or cylinder misfires need checks of idle actuators, plugs, coils and wiring. Diagnose bank-specific faults before blaming the engine controller.
Cooling & leaks. Thermostat faults and coolant leaks need attention before hard use. Monitor oil level, inspect for leaks and warm the oil before using the upper rev range.
Keep it consistent: Bring the engine oil to operating temperature before high rpm and use the model-specific BMW oil specification and service schedule.
References
| Topic | Source |
|---|---|
| U.S. specifications | BMW 2006 M5 press kit |
| Technical operation | BMW MS_S65 Engine Management training |
| North American launch | BMW M5 at the North American International Auto Show |
| Bearing & VANOS-line concerns | Mr Vanos · S85 repair experience |
| Throttle-actuator failure | ECU Testing · S85/S65 actuator repair |
| S85 service concerns | FCP Euro · S85 workshop concerns |
| Photograph | BMW S85 V10 · Auge=mit · CC BY-SA 4.0. First view cropped from the four-view photograph; cropped presentation under the same licence. |
Model years refer to selected U.S. and Canadian applications. Equipment and software vary by build. Use current BMW service information for diagnosis and repair.
