Volvo EPA2007 D13F - Thermostat; Engine Cooling Fan

ENGINECOMPONENTANDLOCATION105
EGRValve
ThisengineusestheEGRvalvetorecirculateexhaustgases.Engineoiloperatesthe
EGRvalve.TheEECUdeterminesthedesirablevalveopeningbasedoninputsfroma
numberofsensorsandcommandstheEGRvalvesolenoidtoopenorclosethevalve.
Corrosionoccursintheinletmanifoldifexhaustgascondensesthere.Thiscan
producebothinternalandexternaldamage.Toeliminatecorrosion,theEECU
comparesengineRPM,torqueload,ambienttemperature,inletmanifoldtemperature
andEGRdemandtocalculatethedewpointintheinletmanifold.Itthenadjuststhe
EGRopeningtostayabovethedewpoint.Additionally,surfaceswithintheinlet
manifoldandthemixingchamberaretreatedtoresistcorrosion.
TheEGRvalveattachestotherearsectionoftheexhaustmanifoldforreliable
responseandturbochargerefciency.ThislocationalsoprotectstheEGRcoolerfrom
harmfulhighpressureexhaustpulsesthatoccurduringenginebraking.
EGRValveFunction
WhentheEGRvalveisopen,exhaustgasrecirculatesintothecombustionchamber.
Thevalveisnormallyclosedwhenenginecoolanttemperatureisbelow65°C(149°F)
unlesstheEECUcommandsthevalveopenduringautomaticcoolercleaningmode.
Whencoolanttemperatureexceeds65°C(149°F),engineloadexceeds50%,andRPM
exceeds1200,theEECUopenstheEGRvalvetoapproximately90%ofitsrange.
Atidle,theEECUmonitorsexhausttemperatureeverythreeminutes.Ifitexceeds
98°C(208°F),thevalveopenstoapproximately14%ofitsrange.Otherwise,it
remainsclosed.