Charge Air Cooler Icing Prevention and Detection

WARNING: This page is about a different variant/trim than selected.

Moisture is a natural by-product of the combustion process in a internal combustion engine. The root cause of CAC icing is evaporating moisture stored in the engine oil that is fed into induction system before the turbocharger compressor via the positive crankcase ventilation (PCV) secondary (breather) path. Generally, the secondary PCV path is used at highway speeds, or during transient maneuvers that cause the manifold absolute pressure (MAP) to be greater than 90 kPa (13.1 PSI). High moisture content in the oil may lead to rapid CAC icing during these engine operating conditions when the secondary PCV path is used instead of the primary path. Short distance driving in cold weather conditions can contribute to CAC icing since the moisture in the engine oil increases rapidly, if the oil temperature stays low, colder than 80°C (176°F) over several drive cycles.

Charge Air Cooler Icing Prevention will enable whenever ambient air temperatures exist that are known to contribute to increased moisture content in the engine oil: Ambient air temperature at Cold Startup is -5°C (25°F) or colder for 3 consecutive cold starts where the Oil Temperature was not warmer than 80°C (176°F), for a period of time during the previous 2 engine cycles. When Prevention mode is enabled, the scan tool parameter: High Water Content in Oil Detected will display Yes, an alternate shift schedule is employed (delayed shifting) and the final gear is inhibited. This operating mode allows the engine to operate with lower load at higher engine speeds, that maintain PCV flow through the primary crankcase ventilation path. Prevention mode will reset if: The Oil Temperature was 80°C (176°F) or warmer for a period of time during the previous engine cycle. Or, on the third Cold Start where the ambient temperature at Cold Startup is warmer than -5°C (25°F).

Charge Air Cooler Icing Detection will enable when conditions exist that contribute to CAC icing while driving: Ambient air temperature is -5°C (25°F) or colder and the throttle inlet air pressure (Boost Pressure) is not within a predetermined range of the calculated boost pressure. The scan tool Ice Detected in Charge Air Cooler parameter will display Yes, and the controls system employs the alternate shift schedule described previously, in order to alleviate the icing condition. If the Detection mode is enabled and the Boost Pressure deviation is such that DTC P0299 sets, the scan tool Engine Underboost Due to Ice in Charge Air Cooler will display Yes, and the alternate shift schedule is employed. Detection mode will reset if: At engine shut down the ambient air temperature is -5°C (25°F) or warmer and the ignition remains Off for next 8 hours. Or, the ignition is Off for at least 3 hours and the ambient air temperature is -5°C (25°F) or warmer at next ignition cycle.