The FCD Logger reads standard EOBD data and sends it to the FCD Cloud. The recorded data of the long and short-term adaptives is processed by the intelligent application in the Cloud. Graphs of the processed data are downloaded to the user's PC, with indexed positions pointing out any anomalies in the EOBD data that require more attention.
In this case, the FCD Logger revealed a defect in the active crankcase ventilation system during a procedure performed by the application on the FCD Cloud. If the PCV valve diaphragm fails to seal because of damage, crankcase gases can enter the intake system.
The use of an HC aerosol applied to the intake manifold area will not reveal anything, as the leak is not external but internal. Usually, when there is a vacuum in the intake system, the diaphragm seals the valve seat, preventing gases from the crankcase from flowing into the intake system. These gases do not contain much air in standard conditions. If the crankcase has more pressure than the intake system and the PCV valve opens, the gases won't make the A/F mixture leaner. Defective PCV can result in a lean A/F mixture.
In the FCD Academy, in the chapter describing the function of the crankcase ventilation system, you can read what happens when the diaphragm is damaged and the problem has been neglected for several months (accessible only for registered professional technicians).
The Lambda sensor in the exhaust can still enrich the mixture sufficiently to compensate for excess oxygen and adjust the correct mixture despite the diaphragm in the PCV valve being damaged. It's possible that the exhaust emissions won't exceed the tolerance limits.
At idle, a gasoline engine should use between 0.8 to 1.0 L/h, but this engine's fuel consumption is higher than that. The reason for this is enrichment, which occurs as a result of the leaning effect of gases being drawn in through the torn diaphragm from the crankcase. Why do these gases lean out the mixture despite the previous statement that they contain almost no oxygen? If the diaphragm is torn, then they will, because the PCV valve has two functions. The second function is to vent crankcase gases before the turbocharger, where there is clean air.
The FCD Logger is responsible for generating the red trace, which is not part of the EOBD data. If the test driver follows the specified driving patterns, the cloud application will categorize and predict the fault based on the relationships between multiple traces. The output offers the diagnostician two essential clues: there is an intake leak and it is significant. If the mechanic sprays the outside of the intake system and he does not hear any engine response, it points either to the PCV valve or the brake vacuum booster. Now it's down to him to complete the final simple steps.
The Lambda sensor in the exhaust can still enrich the mixture sufficiently to compensate for excess oxygen and adjust the correct mixture despite the diaphragm in the PCV valve being damaged. It's possible that the exhaust emissions won't exceed the tolerance limits.
At idle, a gasoline engine should use between 0.8 to 1.0 L/h, but this engine's fuel consumption is higher than that. The reason for this is enrichment, which occurs as a result of the leaning effect of gases being drawn in through the torn diaphragm from the crankcase. Why do these gases lean out the mixture despite the previous statement that they contain almost no oxygen? If the diaphragm is torn, then they will, because the PCV valve has two functions. The second function is to vent crankcase gases before the turbocharger, where there is clean air.
The FCD Logger is responsible for generating the red trace, which is not part of the EOBD data. If the test driver follows the specified driving patterns, the cloud application will categorize and predict the fault based on the relationships between multiple traces. The output offers the diagnostician two essential clues: there is an intake leak and it is significant. If the mechanic sprays the outside of the intake system and he does not hear any engine response, it points either to the PCV valve or the brake vacuum booster. Now it's down to him to complete the final simple steps.
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