cbrahs

DESCRIPTION
1. The Aftertreatment System consists of three catalyst elements, all working together to drastically reduce tailpipe emissions:



DIESEL OXIDATION CATALYST (DOC)
The Diesel Oxidation Catalyst (DOC) is a ceramic flow through substrate coated with a catalyst washcoat that is integral to the DOC assembly. The close coupled DOC treats engine exhaust gases by converting harmful carbon monoxide, unburned hydrocarbons and other compounds into water, carbon dioxide and heat.

Pick-up vehicles use a separate DOC assembly.

Cab-Chassis vehicles use a combination Diesel Oxidation Catalyst/Diesel Particulate Filter (DOC/DPF)



CLOSE COUPLED CATALYST (CCC)
The CCC is basically a diesel oxidation catalyst (DOC) that is mounted very close to the turbocharger exhaust outlet. It is a metallic flow through substrate coated with a catalyst washcoat that is essential to the integrated operation of the aftertreatment assembly. The close coupled DOC treats engine exhaust gases by converting harmful carbon monoxide, unburned hydrocarbons and other compounds into water, carbon dioxide and heat. The ability to create heat is an important part of the system regeneration process..



NOx ADSORBER CATALYST (NAC)
The NAC is located downstream of the CCC. Using the heat and exhaust constituents coming from the CCC, the NAC traps various oxides of nitrogen, and then converts those into Carbon Dioxide, Nitrogen (N2) and water via a regeneration process controlled by the engine's electronic control module (ECM). The NAC also plays a role in reducing non-methane hydrocarbons (NMHC) from the exhaust gas.



DIESEL PARTICULATE FILTER
The NAC is located downstream of the CCC. Using the heat and exhaust constituents coming from the CCC, the NAC traps various oxides of nitrogen, and then converts those into Carbon Dioxide, Nitrogen (N2) and water via a regeneration process controlled by the engine's electronic control module (ECM). The NAC also plays a role in reducing non-methane hydrocarbons (NMHC) from the exhaust gas. DIESEL PARTICULATE FILTER (DPF): The diesel particulate filter (DPF) is a wall-pass ceramic filter substrate coated with a catalyst washcoat. It is located just downstream of the NAC. Exhaust gases flow from the NAC into the catalyzed diesel particulate filter (DPF) which traps and accumulates particulate matter, and further treats the exhaust gases to reduce any remaining unburned hydrocarbons and other harmful compounds. The trapped particulate matter will be periodically removed from the DPF via a regeneration process controlled by the engine’s electronic control module (ECM).



OPERATION
The oxidation catalyst raises the exhaust gas temperatures to regenerate the DPF, which is passive regeneration. If the passive regeneration cannot keep up with the build up of soot in the DPF, the ECM will actively regenerate the DPF to burn off the soot. Residue remains inside the DPF in the form of non burnable ash. Ash comes from the oils and other materials that are trapped in the oils and are present in the soot. The catalyst contains a large number of parallel channels, which run in the axial direction and are separated by thin porous walls. The channels are alternatively open at one end, but plugged at the other. The exhaust gases flow through the walls and escape through the pores in the wall material. Particulates, however, are too large to escape and are trapped in the monolith walls. The ECM starts the regeneration of the DPF if the soot load exceeds a performance map value. The ECM determines the load condition of the DPF based upon the exhaust gas pressure upstream and downstream of the DPC/DPF. A pressure differential sensor provides the pressure input to the ECM. During the regeneration process, the ECM raises the temperature in the DOC/DPF to burn off the soot accumulated. Under normal operation, the engine does not produce enough heat to oxidize the soot inside the DOC/DPF. This process requires temperatures above 550 ºC (1,022 ºF). After regeneration, the ECM reads the actual pressure difference at the DOC/DPF and compares it with a reference value. From this comparison, the ECM determines the ash quantity inside the DOC/DPF.



Diagnosis and Testing

DIESEL PARTICULATE FILTER


EVIC Message Center - Message - Catalyst Full
The engine Electronic Control Module (ECM) monitors the soot load in the diesel particulate filter. Under normal operating conditions the diesel particulate filter is self-cleaning, where accumulated soot is converted to ash. Under light load operating conditions, the driver may be notified via the vehicle's Electronic Vehicle Information Center (EVIC) message center "CATALYST FULL: SEE OWNERS MAN" will be displayed on the overhead console of your vehicle if the exhaust particulate filter reaches 80% of its maximum storage capacity. Under conditions of exclusive short duration and low speed driving cycles, your Cummins engine and exhaust aftertreatment system may never reach the conditions required to remove the trapped PM. If this occurs, “Catalyst Full See Owner Manual” will be displayed on the overhead console in your vehicle. If this message is displayed you will hear one chime to assist in alerting you of this condition. Catalyst Stat::::::::::80% Catalyst Stat::::::::::80% will replace the message “Catalyst Full See Owner Manual” after it is displayed for one minute. The engine Powertrain Control Module (PCM) will continue to monitor the amount of particulate matter trapped in the particulate filter. This message indicates the percentage of the particulate filter capacity that has been used. By simply driving your vehicle at highway speeds for as little as 45 minutes you can remedy the condition in the particulate filter system and allow your Cummins engine and exhaust aftertreatment system to remove the trapped PM and restore the system to normal operating condition. Catalyst Stat:::::::::::80%, 90%, 99% Catalyst Stat:::::::::::80%, 90%, 99% If you are unable to drive your vehicle under these conditions for an extended period of time after the initial warning notification, the Engine PCM will continue to monitor the particulate filter and will display the progression of particulate filter usage (80, 90, 99%) on the EVIC message center. CATALYST FULL SERVICE REQD If the particulate filter reaches 99% of its capacity, the overhead console in your vehicle will chime twice and display the message CATALYST FULL SERVICE REQD. At this point the engine PCM will register a fault code, the instrument panel will display a MIL light and the engine PCM will derate the truck, reducing its horsepower and torque output. The PCM derates the engine in order to limit the likelihood of permanent damage to the aftertreatment system. If this condition is not corrected and a dealer service is not performed, extensive exhaust aftertreatment damage can occur. In order to correct this condition it will be necessary to have the truck serviced by your local authorized dealer.

Intervention Regeneration Strategy – EVIC Message Process Flow (Late Build) The Cummins diesel engine meets all EPA Heavy Duty Diesel Engine Emissions Standards, resulting in the lowest emitting diesel engine ever produced. NOTE: Depending on the build date of your vehicle or if the software has been updated, the EVIC may display the following messages. To achieve these emissions standards, your vehicle is equipped with a state-of-the-art engine and exhaust system. The engine and exhaust after-treatment system work together to achieve the EPA Heavy Duty Diesel Engine Emissions Standards. These systems are seamlessly integrated into your vehicle and managed by the Cummins Powertrain Control Module (PCM). The PCM manages engine combustion to allow the exhaust system’s catalyst to trap and burn Particulate Matter (PM) pollutants, with no input or interaction on your part. Additionally, the overhead console in your vehicle has the ability to alert you to additional maintenance required on your truck or engine. Refer to the following messages that may be displayed on your Electronic Vehicle Information Center (EVIC):

Exhaust System — Regeneration Required Now “Exhaust System—Regeneration Required Now” will be displayed on the overhead console of your vehicle if the exhaust particulate filter reaches 80% of its maximum storage capacity. Under conditions of exclusive short duration and low speed driving cycles, your Cummins diesel engine and exhaust aftertreatment system may never reach the conditions required to remove the trapped PM. If this occurs, “Exhaust System — Regeneration Required Now” will be displayed on the overhead console in your vehicle. If this message is displayed, you will hear one chime to assist in alerting you of this condition. By simply driving your vehicle at highway speeds for as little as 45 minutes, you can remedy the condition in the particulate filter system and allow your Cummins diesel engine and exhaust after-treatment system to remove the trapped PM and restore the system to normal operating condition. Exhaust Filter XX% Full Indicates that the Diesel Particulate Filter (DPF) is approaching full. Exhaust System — Regeneration in Process Indicates that the Diesel Particulate Filter (DPF) is selfcleaning. Maintain your current driving condition until regeneration is completed. Exhaust System — Regeneration Completed Indicates that the Diesel Particulate Filter (DPF) selfcleaning is completed. If this message is displayed, you will hear one chime to assist in alerting you of this condition. Service Required — See Dealer Now Regeneration has been disabled due to a system malfunction. At this point the engine PCM will register a fault code, the instrument panel will display a MIL light. IMMEDIATE SERVICE IS REQUIRED. See your authorized dealer as damage to the exhaust system could occur soon with continued operation. Exhaust Filter Full — Power Reduced See Dealer The PCM derates the engine in order to limit the likelihood of permanent damage to the after-treatment system. If this condition is not corrected and a dealer service is not performed, extensive exhaust after-treatment damage can occur. In order to correct this condition it will be necessary to have your vehicle serviced by your local authorized dealer. IMMEDIATE SERVICE IS REQUIRED. See your authorized dealer, as damage to the exhaust system could occur soon with continued operation.

garymcbroom

I will assume that if my tailpipe is full of soot and the bumper and side of the truck is also coated that the filter is defective. I have this problem and my dealer will not change it for various excuses...is this correct?

cbrahs

not really. I have not seen a dealer replace one just cause it is causing the issue you are stating.