| 摘要 |
PROBLEM TO BE SOLVED: To stably ensure negative pressure to a negative pressure actuator using the negative pressure in a downstream side of an intake air amount control system, without causing a deterioration in fuel consumption and drivability in a lean-burn internal combustion engine. SOLUTION: This lean-burn internal combustion engine is provided with an engine capable of stoichiometric combustion operating or lean-bum operating, an intake air amount control system for adjusting the amount of intake air to the engine, a negative pressure actuator actuated by using negative pressure taken from a downstream side of the intake air amount control system, a negative pressure reduction detecting means for detecting the reduction of negative pressure acting on the negative pressure actuator, and a combustion controlling means for switching the engine to either one of stoichiometric combustion operation or leanburn operation according to a detected value of the negative pressure reduction detecting means. In the case where the negative pressure reduction detecting means is out of order, the lean-bum operation is prohibited.
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