Modern Engine Control Units (ECUs) are sophisticated embedded computers that manage every aspect of engine operation. Understanding their architecture is essential for effective calibration work.

Обзор

An ECU receives inputs from dozens of sensors, processes this data through complex algorithms running in real-time, and controls actuators to optimize combustion, emissions, and drivability. Modern ECUs like Bosch EDC17, MD1, MG1, and Continental Simos execute thousands of calculations per crankshaft revolution.

Hardware Architecture

• Microcontroller — typically 32-bit processors (Infineon TriCore, Renesas) running at 100-300 MHz
• Flash Memory — stores calibration data (maps) and program code, typically 2-8 MB
• RAM — working memory for real-time calculations, typically 128-512 KB
• EEPROM — stores adaptation values, fault codes, and learned parameters
• Input Conditioning — analog-to-digital converters, signal filtering, protection circuits
• Output Drivers — high-side and low-side drivers for injectors, coils, solenoids

Input Signals

• Crankshaft Position (CKP) — engine speed and position reference
• Camshaft Position (CMP) — cylinder identification and VVT feedback
• Mass Air Flow (MAF) — intake air mass measurement
• Manifold Absolute Pressure (MAP) — intake manifold pressure
• Throttle Position (TPS) — driver demand input
• Coolant Temperature (ECT) — engine thermal state
• Intake Air Temperature (IAT) — air density correction
• Lambda/O2 Sensors — exhaust gas composition feedback
• Knock Sensors — combustion quality monitoring
• Rail Pressure Sensor — fuel system pressure (diesel)
• Boost Pressure Sensor — turbo output monitoring

Output Controls

• Fuel Injectors — precise fuel metering
• Ignition Coils — spark timing (gasoline)
• Turbo Actuator — boost pressure regulation
• EGR Valve — exhaust gas recirculation
• Throttle Body — electronic throttle control
• VVT Solenoids — cam phasing control
• Fuel Pump — rail pressure control (diesel)

Real-Time Constraints

ECU software operates under strict timing requirements:

• Angle-synchronous tasks — execute at specific crankshaft positions (injection, ignition)
• Time-synchronous tasks — execute at fixed intervals (1ms, 10ms, 100ms loops)
• Event-driven tasks — respond to external events (knock detection, fault handling)

At 6000 RPM, the ECU has only 10ms per revolution to complete all calculations — this is why calibration errors can cause immediate problems.

Software Structure

Sensor Inputs → Signal Conditioning → Physical Models
         ↓
Torque Request Calculation
         ↓
Coordinator (airpath, fuel, ignition, emissions)
         ↓
Actuator Commands → Output Drivers

Calibration Data

The “tune” or “map” is the calibration data stored in flash memory. This includes:

• 2D Maps — single-axis lookup tables (e.g., coolant temp correction vs temperature)
• 3D Maps — two-axis lookup tables (e.g., boost target vs RPM and load)
• Scalars — single values (e.g., rev limiter threshold)
• Switches — on/off flags (e.g., feature enable/disable)

Common ECU Families

• Bosch EDC17 — widespread diesel ECU (2007-2018)
• Bosch MD1/MG1 — current generation diesel/gasoline
• Bosch MED17 — gasoline direct injection
• Continental Simos — VAG gasoline applications
• Delphi DCM — various diesel applications
• Denso — Toyota/Subaru applications

Best Practices

• Understand the ECU family before attempting calibration
• Always backup original calibration data
• Changes must respect the internal logic and safety systems
• Modern ECUs are highly integrated — changing one map affects many others