| 摘要 |
A system detecting leakage of an internal combustion engine having a secondary air passage, bypassing a throttle valve, at an air intake pipe connecting to the intake manifold and a secondary air control valve which regulates opening of the secondary air passage. In the system, when the changes in the absolute manifold pressure and the atmospheric pressure before and after the engine starts rotation, are small, it is determined that the intake manifold may possibly leak and should be monitored. Specifically, the opening of the secondary air passage is changed and the changes in the pressure, etc., before and after the opening is changed, are calculated and based thereon, it is determined whether the intake manifold, in fact, leaks. With this, it becomes possible to detect intake manifold leakage accurately with a simple configuration.
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