Exhaust Gas Recirculation (EGR) reduces nitrogen oxide (NOx) emissions by recirculating a portion of exhaust gas into the intake manifold. This dilutes the fresh charge with inert gas, lowering peak combustion temperatures.
Übersicht
Modern engines use high-pressure EGR (upstream of turbine) or low-pressure EGR (downstream, after DPF). The ECU modulates EGR valve position based on engine load, RPM, and temperature.
Controlled Signals
- EGR valve position
- EGR cooler bypass valve
- Intake manifold pressure
- MAF / MAP sensors
- EGR temperature sensor
Maps Involved
- EGR Rate Target Maps vs RPM/load
- EGR Valve Position Maps
- EGR Cooler Bypass Maps
- EGR Temperature Limits
Logic Sequence
Operating Conditions → EGR Rate Lookup
↓
Temperature / Altitude Corrections
↓
EGR Valve Command
↓
MAF-based Feedback Verification
Calibration Objectives
- Minimize NOx emissions
- Maintain drivability and response
- Prevent intake contamination
Calibration Strategy
- EGR delete requires full ECU adaptation to prevent faults
- Reducing EGR increases NOx but may improve response
- Monitor intake manifold for carbon buildup
Diagnostik
- EGR valve position faults
- EGR flow insufficient/excessive
- Intake manifold pressure deviation
Best Practices
- EGR delete is emissions-illegal in most jurisdictions
- Regular cleaning extends EGR life on stock vehicles
