Engine Performance (A8)第 95 / 120 题
Technician A says a vacuum leak causes a rich condition. Technician B says a vacuum leak adds unmetered air and causes a lean condition, especially at idle. Who is correct?
a.Technician A only
b.Technician B only
c.Both A and B
d.Neither A nor B
解析
A vacuum leak lets extra air enter after the mass airflow sensor, leaning the mixture and often causing a rough idle and positive fuel trim. Technician B is correct. Smoke testing helps locate intake leaks.
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