Abstract: First and second cam covers define at least parts of first and second cam chambers respectively. Blow-by gas produced in an internal combustion engine is conducted to the first and second cam chambers. A communication passage connects the first and second cam chambers. A gas passage connects the communication passage and an air intake passage of the engine. A device disposed essentially at the connection between the communication passage and the gas passage serves to keep oil out of blow-by gas being drawn back into the air intake system of the engine.

Abstract: An exhaust gas purification control apparatus for an internal combustion engine wherein vacuum signals applied to air fuel mixture control, exhaust gas recirculation control, and ignition timing control are modified by a vacuum signal modifier. The vacuum signal modifier is operative in response to a pressure signal applied thereto. This pressure signal is produced by a pressure signal control device by diluting a venturi vacuum with air.