Engine Performance (A8)Câu 106 / 120
A vehicle fails an emissions test for high hydrocarbons (HC). This is most commonly associated with:
a.Excessive coolant
b.Low tire pressure
c.Unburned fuel from misfire, ignition, or rich-condition problems
d.A worn wheel bearing
Giải thích
High HC indicates unburned fuel escaping into the exhaust, typically from misfires, ignition faults, or an overly rich mixture. Diagnosing the misfire or fuel-control fault reduces HC. A failing catalytic converter can also raise tailpipe HC.
Luyện miễn phí toàn bộ 120 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A loose or missing fuel cap most commonly sets which type of code?
- Technician A says low fuel pressure can cause a lean misfire and hesitation. Technician B says a clogged fuel filter or weak pump can lower fuel pressure. Who is correct?
- The throttle position sensor (TPS) informs the PCM about:
- The PCM uses the crankshaft position sensor primarily to:
- On an OBD-II vehicle, the data link connector (DLC) used to retrieve codes is standardized as a:
- The exhaust gas recirculation (EGR) system reduces which emission by lowering combustion temperature?
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