DIAGNOSTICMANUAL
9.6.SYMPTOM5(HEAVYDUTY):BLACKSMOKE
OVERVIEW:Hydrocarbonslipoccurswhendieselfueldoesnotfullycombustintheaftertreatment
systemandslipsthroughtheDPFintothecleansideoftheexhaust.Hydrocarbonslipisassociated
withhighidletime.TheDPFshouldNOTbereplacedduetoblackstainingintheexhaust.
NOTE–TheDieselParticulateFilter(DPF)isnot100percentefcient.Someevidenceofexhaustsoot
isnormal,anddoesnotindicateamalfunctioningDPF.
WARNING
Topreventunexpectedmovementofthevehicleandpossibleinjuryordeath,parkthe
vehicleonaat,levelsurface,applytheparkingbrake,turntheengineoffandchockthe
wheelstopreventvehiclefrommovingineitherdirection.
NOTE–Beforebeginningthefollowingstep-baseddiagnostics,performallvehicleoperationalchecks
page80.
Step
ActionDecision
1
DieselParticulateFilter(DPF)SnapAccelerationTest
(QuickT est).ThisprocedurecheckstheDPFforcracks
orinternaldamagewithoutremovingtheDPFfromthe
vehicleandisusedtotestbasicfunctionalityoftheDPF.
ThisistobedonepriortoremovingtheDPF .
1.Thetransmissionmustbeinneutralandthe
parkingbrakeapplied.
2.Startandidletheengine.
3.Rapidlysnaptheacceleratorpedalfrom
idletofullthrottle.Thiscanbeperformed
multipletimes.
4.Duringtheengineaccelerations,visually
checkforaheavyblacksmokeexitingthe
exhaustpipe.
Isblacksmokevisible?
Yes:Gotostep2
Endofdiagnostics
113
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