Crankcase integrity breach detection

摘要

Methods and systems are provided for using a crankcase vent tube pressure or flow sensor for diagnosing a location and nature of crankcase system integrity breach. The same sensor can also be used for diagnosing air filter plugging and PCV valve degradation. Use of an existing sensor to diagnose multiple engine components provides cost reduction and sensor compaction benefits.

主权项

1. An engine crankcase ventilation system, comprising:
an engine including an intake passage and a crankcase; a starter motor; a crankcase vent tube mechanically connected to the intake passage upstream of a compressor, the tube also mechanically connected to the crankcase via an oil separator, the vent tube located external to the engine; a sensor coupled in the crankcase vent tube for estimating a vent tube pressure; and a control system with computer readable instructions for,
during an engine start,
cranking the engine with the starter motor, and indicating crankcase ventilation system degradation based on each of a transient dip in the vent tube pressure being lower than a threshold amplitude during engine cranking when manifold airflow is below a threshold and a change in vent tube vacuum being lower than a change in manifold airflow during engine running when manifold air flow is above the threshold, wherein the engine is cranked by the starter motor at least before a first combustion event from rest.