The new TITAN XD Diesel with the all-new CUMMINS 5.0L V8 TURBO DIESEL engine provides exceptional Particulate Matter (PM) control based on the latest emission technologies.

The combustion process in the TITAN XD diesel engine produces Particulate Matter (PM) at levels high enough that they must be captured or eliminated in the exhaust system to meet emission standards. This is similar for most diesel engines. You may have seen the black smoke that some diesel vehicles emit.

TWO TYPES OF PM ARE CREATED IN THE COMBUSTION PROCESS:

SOOT – Composed of partially burned particles of fuel that occur during normal engine operation (black smoke). Soot-based PM is trapped and oxidized (changed into a gas) by the regeneration process in the DPF.

ASH – Composed of partially burned particles of engine oil that occur during normal engine operation. Ash-based PMs cannot be oxidized since they are mostly metal and are instead trapped and accumulated inside the DPF. This PM will accumulate and may, in time, clog the DPF, which will necessitate DPF replacement. Ash-based PM should be produced in only very small quantities. Non-approved oils are regarded as a major cause of ash buildup in the DPF.

THE DPF, PIECE BY PIECE

  1. Aftertreatment Inlet NOx Sensor – Measures the amount of NOx coming out of the engine and entering the aftertreatment system.
  2. DPF Temperature Sensor Module – A three-probe sensor where one probe tracks temperature levels at the DOC inlet, another monitors temperature at the DPF inlet, and the third probe monitors the exhaust temperature as it exits the DPF.
  3. DPF Differential Pressure Sensor – A two-probe pressure sensor where one probe is located before the DPF and the other is located after the DPF. This sensor measures the difference in exhaust gas pressure before the DPF and after the DPF. This measurement is used by the ECM to determine soot load in the DPF.

DOC AND DPF ASSEMBLY

Diesel Oxidation Catalyst (DOC)

  • The DOC is used to create additional heat, if needed, for the regeneration process.
  • If the ECM, using sensor inputs, determines that additional heat is needed for regeneration, it will command the injectors to inject fuel into the cylinders post combustion (very late in the power stroke or during the exhaust stroke).
  • Fuel injected post combustion will not ignite or burn because there is no oxygen (required for combustion) and there is no pressure (required for ignition).
  • The DOC captures unburned fuel (hydrocarbons) in the exhaust and converts it into flame-free heat.

Diesel Particulate Filter (DPF)

  • DPF collects and stores PM on the walls and surfaces inside the DPF.
  • DPF oxidizes soot via regeneration when the temperatures are high enough.
  • Ash is trapped and accumulated inside the DPF. Ash will accumulate and may, in time, clog the DPF, which will necessitate DPF replacement.

THE HEAT IS ON: REGENERATION

Regeneration refers to the removal of soot-type PM from the exhaust via oxidation within the DPF. There are three types of regeneration: PASSIVE, ACTIVE, and STATIONARY. Here, we will give an overview of these three types of regeneration. For regeneration details, refer to the EX section of the ESM.

PASSIVE REGENERATION

  • Passive regeneration occurs when the exhaust temperatures are naturally high enough (no additional heat is needed from the DOC) to oxidize the soot in the DPF faster than it is collected.
  • Passive regeneration typically occurs when the temperature of the DPF is above 572°F (300°C). This occurs during highway driving or when driving with heavy loads.
  • Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration.

ACTIVE REGENERATION

  • The term “active” refers to the fact that the ECM must take action to produce additional heat to initiate the regeneration process.
  • Active regeneration occurs when exhaust temperatures are not naturally high enough to oxidize the soot in the DPF faster than it is collected.
  • For active regeneration to occur, the Engine Control Module (ECM) must detect that the DPF restriction has reached a specified limit. Once this limit is reached, the ECM will alter engine operation in order to create exhaust temperatures high enough to actively regenerate the DPF.
  • This is typically done by injecting a small amount of diesel fuel into the exhaust stream, which is then oxidized by the DOC.
  • The oxidation of this additional fuel raises the exhaust temperatures to approximately 1,022°F (550°C), which is needed to regenerate the DPF.

STATIONARY REGENERATION

  • Stationary regeneration is performed by a service technician.
  • If the vehicle is operated continually in conditions in which passive and active regeneration are not sufficient to clear soot out of the DPF, a stationary regeneration may be needed. If this occurs, the DPF lamp will illuminate.
  • Refer to the EX section of the ESM for details on stationary regeneration. Make sure to follow all ESM instructions, warnings, and cautions when performing stationary regeneration.

Exhaust system components can become hot enough during operation and testing to cause burns or ignite and melt combustible materials. The exhaust and exhaust components can remain hot after the vehicle stops moving and has been shut down. To avoid the risk of fire, property damage, burns or other serious personal injury, allow the exhaust system to cool before beginning repairs or service. Make sure that no combustible materials are located where they are likely to come in contact with hot exhaust or exhaust components.

REGENERATION AND NORMAL DAILY OPERATION

Normally, particulate matter accumulated in the DPF is automatically burned and converted to harmless substances during driving. Passive or active regeneration occurs automatically with normal operation of the vehicle. However, particulate matter collected in the DPF cannot be burned under the following conditions:

In these cases, passive or active regeneration is not sufficient to burn the particulate matter that accumulates in the DPF. As a result, the DPF Warning Lamp in the meter will illuminate. This is not a malfunction. If the DPF Warning Lamp comes ON, drive the vehicle so that normal automatic regeneration (passive or active depending on the temperatures in the DPF) can occur.

DRIVE PATTERN TO FACILITATE AUTOMATIC REGENERATION

NOTE: If the vehicle continues to be driven with the DPF Warning Lamp illuminated and without doing the automatic regeneration, the fail-safe will limit the engine rpm and/or torque. In this case, it is recommended to perform the stationary regeneration procedure.

GOOD TO KNOW

The TITAN XD has an aftertreatment warm-up system. The aftertreatment warm-up feature activates during periods of extended idle time. The purpose of this feature is to increase the temperature of the aftertreatment system to remove any water condensation that has built up during the idle time.

When the ECM detects that the exhaust temperature entering the aftertreatment system has been below 150°C (302°F) for approximately 2 hours, the ECM automatically increases the engine speed to about 1,000 rpm for approximately 10 minutes, but does not inject additional fuel.

The following conditions must be met to activate aftertreatment warm-up:

HEADS UP: DPF LEVEL WARNINGS AND SYSTEM ERROR MESSAGES

If the DPF Warning Lamp comes ON and a message is displayed in the Vehicle Information Display (VID), it indicates that particulate matter has accumulated in the DPF to the specified limit (overload condition).

The following are the three DPF warning conditions that can occur:

EXHAUST FILTER OVERLOADED (See Owner’s Manual for Drive Pattern)

When this message is displayed on the VID, the vehicle should be driven on the highway where the road conditions safely allow speeds over 55 mph for at least 45 minutes.

DPF Lamp State: Solid DPF Lamp

EXHAUST FILTER OVERLOADED ENGINE POWER REDUCED (See Owner’s Manual)

Engine torque and speed will be reduced. There are two severities of this message. The MIL will illuminate when the exhaust filter is at the more severe level.

When MIL is OFF: The vehicle should be driven on the highway (over 55 mph) for at least 45 minutes. Engine torque is limited.

When MIL is ON: Driving the vehicle on the highway will no longer recover the DPF. Stationary regeneration is required. Engine speed limited to 2,300 rpm.

DPF Lamp State: DPF Lamp Blinking

EXHAUST FILTER OVERLOADED IMMEDIATE SERVICE REQUIRED (See Owner’s Manual for Drive Pattern)

Engine speed and torque will be limited. Engine speed limited to 2,300 rpm. Immediate service is required.

MIL State: MIL ON

DPF Lamp State: DPF lamp blinks quickly.