Direct Injection Engines + Smog — Carbon Buildup Issues
Direct injection sprays fuel directly into the combustion chamber (vs port injection which sprays into the intake port). Higher efficiency but causes carbon buildup on intake valves over time (because no fuel washes them). Common smog issue on 2.0T BMW, Audi, VW, Mercedes, plus 1.5T Ford EcoBoost, GDI Hyundai/Kia.
Common Direct Injection (DI/GDI) smog issues
Carbon buildup on intake valves, misfire codes, reduced power
How to fix
Walnut blast intake cleaning every 60-80k miles
Typical repair cost
$300-$600 for walnut blast service
Common questions
What is Direct Injection (DI/GDI)?
Direct injection sprays fuel directly into the combustion chamber (vs port injection which sprays into the intake port). Higher efficiency but causes carbon buildup on intake valves over time (because no fuel washes them). Common smog issue on 2.0T BMW, Audi, VW, Mercedes, plus 1.5T Ford EcoBoost, GDI Hyundai/Kia.
What causes a Direct Injection (DI/GDI) smog failure?
Carbon buildup on intake valves, misfire codes, reduced power
How is Direct Injection (DI/GDI) fixed?
Walnut blast intake cleaning every 60-80k miles
What does fixing cost?
$300-$600 for walnut blast service