Abstract: Methods and systems are provided for monitoring a crankcase ventilation system. In one example, a method may include diagnosing a breach in a crankcase vent tube based on a regression of measurements of pressure in the crankcase vent tube. The regression allows the pressure measurements to be extended across an entire range of operating air flows and the breach may be identified by comparing the regressed pressure measurements to expected crankcase vent tube pressures.

Abstract: Fuel gelling determination methods and systems are provided for identifying and displaying to a vehicle operator a message conveying that the conditions are suitable for the formation of a fuel gel. In one particular example, at a fuel refill event the average ambient air temperature is calculated over the last fifty miles and used to characterize the grade of fuel as a summer or winter grade of fuel. Then, when the ambient temperature next drops near the cloud point of a summer fuel grade while driving, a message is displayed to a vehicle operator indicating that the conditions are suitable for fuel gelling to occur.

Abstract: Fuel gelling determination methods and systems are provided for identifying and displaying to a vehicle operator a message conveying that the conditions are suitable for the formation of a fuel gel. In one particular example, at a fuel refill event the average ambient air temperature is calculated over the last fifty miles and used to characterize the grade of fuel as a summer or winter grade of fuel. Then, when the ambient temperature next drops near the cloud point of a summer fuel grade while driving, a message is displayed to a vehicle operator indicating that the conditions are suitable for fuel gelling to occur.