Navistar MaxxForce 15 - 10.7. GRAPH 7: INVERTED EXHAUST GAS TEMPERATURES (INEFFICIENT DOC); Graph Analysis:

DIAGNOSTICMANUAL
10.5.GRAPH5:LUGDOWNTEST(ENGINESPEED,APP1,VEHICLESPEED,ANDIMP)
1.IntakeManifoldPressure(IMP)
(psi)[Purple]
2.Enginespeed(rpm)[Blue]
3.Vehiclespeed(mph)[Red]
4.Engineload(percent)[Orange]
5.AcceleratorPedalPosition1
(APP1)(percent)[Green]
Figure30Graph5:LugDownTest(EngineSpeed,APP1,VehicleSpeed,andIMP)
GraphAnalysis:
ThisgraphshowstheIntakeManifoldPressure(IMP)signalvaluerespondingasdesigned.Thistestdoesnot
givepassorfailresults.ItonlyallowstheusertovalidateIMPsignalvalueunderload.Enginepowerbandis
typicallybetween1300to1700rpmwithpeakpoweroccurringaround1600rpm.Anythingoutsideofthis
powerbanddropsboostandpowersignicantly.AcceleratorPedalPosition1(APP1)signalvaluemustbe
99.6%tosuccessfullyreachpeakboostduringthistest.LowIMPcanbetheresultoflowFuelRailPressure
(FRP),orhighTurbocharger1TurbineOutletPressure(TC1TOP).DiagnoselowFRPconcernsrst,high
TC1TOPconcernssecond,andlowIMPconcernsthird.
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