Emissions Service For Diesel Trucks & Fleets

A truck’s diesel engine emissions system functioning properly not only ensures it will pass government regulated inspections; it also ensures good fuel economy, optimal horsepower, and maximum truck performance. Cummins Automotive & Diesel Service can run diagnostics such as with diesel air intake residuals and symptoms calculations based on sensor fault detection data from engine speed, manifold pressure, manifold temperature, and air mass, to check the emissions components on your diesel truck for needed maintenance to ensure your truck is operating at its peak emissions performance.

With computer diagnostic software and troubleshooting tools for Class 3 to Class 8 commercial trucks and for medium to heavy duty pickup trucks, the Cummins Automotive & Diesel Service technicians can get from fault to fix quicker than ever with fast and accurate repairs. Today’s diesel trucks are complex vehicles, incorporating an ever increasing lineup of components and electrical systems which can make service and maintenance a moving target. Computer diagnostics steady that target by simplifying repair procedures with detailed troubleshooting procedures, bi-directional tests, comprehensive data points, precise wiring diagrams, and accurate installation guides.

We do not waste time while diagnosing trucks. With a computer diagnostic interface that links to the truck, the connection is set to diagnose the ECU (Electronic Control Unit) and all components, find all relevant tests, review pertinent data points, and reference fault logics to enable technicians to diagnose root causes for the precise and accurate repair while also addressing other, symptom related issues. Superb bi-directional testing capability allows for the adjustment of engine parameters with the ability to run live component commands and tests. Additionally, our supplemental, symptoms based repair guides allow us to detect and repair the problem when the diagnostic tools are blind in the cases when there is not a fault code signifying the problem. With the capability to detect every issue on your truck, our diagnostics save you time and money.

2019 Brings Tough Challenges For Portland’s Trucking Industry

The 2019 Oregon State Senate and House of Representatives, both passed a bill to further regulate diesel trucks in the Portland metro area, requiring truck owners to replace their older diesel engines with newer models by the year 2025. The lawmakers’ goal is the reduction of diesel pollution by making newer engines mandatory; technologically advanced engines whose low emissions systems allows them to filter out nearly all toxic diesel particulate matter. The bill requires truck owners to replace their older diesel engines with a 2010 model year engine, or newer. With the onus of the cost of replacement being placed on truck owners, perhaps the bill’s wrinkle of the inclusion of funds coming from the approximate $50 million from the Volkswagen diesel emissions scandal settlement, to help pay for engine upgrades, will help our strapped Portland metro trucking industry make these required engine upgrades with a little less pain.

2022 Assistance For Portland’s Diesel Truck Owners

The Oregon Department of Environmental Quality is providing $8 million in grant funding to reduce diesel emissions in Oregon in 2022. Revenue for this program is provided by the Environmental Mitigation Trust Fund, subject to the settlement agreement between the United States and Volkswagen Group of America, Inc. In 2019, the Oregon Legislature authorized the creation of a grant program supporting businesses, governments and equipment owners in replacing older and more polluting diesel engines with new, cleaner technologies and exhaust control retrofits. These grants are available for qualifying truck owners.

Assistance Resources

Key Dates For 2022

The below, estimated dates are subject to change.

April 5, 2022: Grant program opens for applications
June 7, 2022: Grant program closes for applications
Aug. 8, 2022: Grant awards announced
Jan. 15, 2023: Funding for projects becomes available

Oregon DEQ & Diesel Truck Emissions

The Oregon Department of Environmental Quality uses a wide variety of tools to help ensure that businesses and individuals comply with state and federal environmental laws. These tools include technical assistance, compliance inspections, investigation of complaints, warning letters, assessment of civil penalties, and compliance orders.

Today’s trucks are manufactured with a Check Engine Light. When the DEQ’s onboard diagnostic test recognizes that this malfunction indicator is commanded on, the truck will fail the diagnostic test. However, as intended, some truck and fleet owners respond to their Check Engine Light by seeking repairs promptly rather than waiting until shortly before the DEQ’s two-year, periodic inspection. 

Prompt action in addressing emissions diagnostic problems prevents excess air pollution. Prompt action, and today’s newer model trucks which are manufactured to operate cleaner, are two reasons why the truck DEQ diagnostic failure rates among VIP programs across the country are so low. The truck manufacturers, the Federal Test Procedure certification emissions test, the DEQ’s onboard diagnostic test, the preventative nature of the Check Engine Light, the trucking industry, and local diesel repair shops, all work together to properly maintain diesel truck fleets to reduce air pollution.

Stop Throwing That Smoke – An Emissions Standards Timeline

1963 – Clean Air Act was passed, introducing Federal Emissions Standards.
1991 – Federal Emissions Standards were introduced to reduce particulate matter.
1994 – Federal Emissions Standards introduced mandating the reduction of particulate matter by 60%.
1998 – Federal Emissions Standards implemented to limit Nitrogen Oxide (NOx) over a gradual time frame with ever stricter limits.
2004 – Federal Emissions Standards introduced to further restrict NOx.
2007 – Federal Emissions Standards introduced to reduce particulate matter to 0.01 g/bhp-hr (96% lower than the 1991 standard) and to enforce a phase-in time period, from 2007 to 2010, requiring further NOx level reductions that were 90% lower than the levels introduced in 2004.
2022 – EPA proposed a rule to set more stringent greenhouse gas (GHG) standards and to significantly reduce emissions of Nitrogen Oxides (NOx), starting in 2027.

Diesel Truck Emissions Technology Development

The timeline above portrays the picture of the continual pressures upon the manufacturers in the trucking industry to find technologies that would meet the demands of the government’s regulations which continued to ratchet down on allowable emissions. To meet the early regulations, engine manufacturers used the technologies of new piston designs, injector spray angle alterations, and electronically controlled injection systems to clear the air.

These technologies created higher injection pressures and eventually the high pressure common rail fuel injection systems were introduced to help reduce particulate matter. Following the common rail technology, Exhaust Gas Recirculation (EGR) systems were implemented to reduce NOx. Then, to fend off demands for further reductions in both NOx and particulate matter, the Diesel Oxidation Catalyst (DOC), the Diesel Particulate Filter (DPF), active regeneration and passive regeneration, the Selective Catalyst Reduction (SCR) system, and the Diesel Exhaust Fluid (DEF) technologies were introduced.

Emissions systems are manufactured with specifications designed to redirect engine exhaust, reduce exhaust noise, and reduce the emissions of hydrocarbons (HC), carbon monoxide (CO), and soluble organic fraction (SOF). Because emissions are thoroughly monitored, with the heavy dependence of the U.S. economy on diesel power to deliver the goods, optimal emissions are central to your success.

Other emissions components are covered in more detail, below, but oxygen sensors, PCV breathers, valves & hoses, carbon vapor canisters, purge valves, smog pumps, air injection pumps, valves & hoses, and Eco CARB EPA compliant direct fit catalytic converters are important components in diesel truck emissions systems. Their proper function is crucial to the efficacy of emissions reductions. Cummins Automotive & Diesel Service can check these components for you and make sure, if it would prove beneficial to your system, that you are set up with AFR sensors and Lambda Controls.

Diesel Truck Exhaust Emissions Acronyms

ATD – After Treatment Device
Bp – Backpressure (Back Pressure)
CCM – Catalytic Converter Muffler
CCV – Crankcase Ventilation
CCV – Closed Crankcase Vent
CFM – Cubic Feet per Minute
CFS – Crankcase Filtration System
CO – Carbon Monoxide
dBA – Decibel, A scale (noise level)
DMF – Diesel Multi-stage Particulate Filter
DOC – Diesel Oxidation Catalyst
DPF – Diesel Particulate Filter
EAT – Exhaust After Treatment
EDM – Emissions Device Monitor
EGR – Exhaust Gas Recirculation
EIEO – End In / End Out (muffler style)
EISO – End In / Side Out (muffler style)
FTP – Federal Test Procedure
HC – Hydrocarbon (unburned fuel)
HP – Horse Power

HTEF – High Temperature Exhaust Filter
ICC – Independent Catalytic Converter
IOM – Installation Operation Manual
LNF – Low NO2 Filter (muffler)
LXF – Low NOx Filter (muffler)
LSD – Low Sulfur Diesel (fuel)
LTF – Low Temperature Filter (muffler)
NOx – Nitrogen Oxide
OCV – Open Crankcase Ventilation
PM – Particulate Matter
SC – Silicone Carbide
SCR – Selective Catalyst Reduction
SEF – Semi-active Electric Filter (muffler)
SIEO – Side In / End Out (muffler style)
SISO – Side In / Side Out (muffler style)
SOF – Soluble Organic Fraction
SRF – Standard Recirculation Filter
ULSD – Ultra-Low Sulfur Diesel (fuel)
VOC – Volatile Organic Compound
VOF – Volatile Organic Fraction

Emissions & The Diesel Exhaust Aftertreatment System

Do you need maintenance, repair or replacement of the DOC, DPF or SCR in your diesel truck’s exhaust aftertreatment system?

The aftertreatment system is the workhorse for reducing harmful diesel exhaust emissions and cleaning exhaust gases from the truck’s exhaust with an assortment of filters, catalysts, sensors and devices to ensure the engines meet emission regulations. Harmful emission gases in the exhaust stream move from the exhaust side of the turbo through the exhaust piping and pass on, downstream, through the filters and catalysts in the aftertreatment system.

Diesel engine emissions contain particulate matter, resulting from unburned fuel. Diesel particulate matter is a composition of very small particles that are composed of solid elemental carbon cores which have organic carbon compounds adhering to the surfaces. The organic carbon includes polyaromatic hydrocarbons. Sulphates and heavy metals are also said to be in diesel particulate matter. Today, particulate matter is nearly completely removed by the exhaust aftertreatment system and are reduced to the eco-friendly elements of water and oxygen. It is important to keep a truck’s emissions running at optimal performance. Without regular and timely maintenance of the system, poor performance, poor fuel efficiency or even component failure can result.

EGR System

Exhaust Gas Recirculation (EGR) valves are a key component in the diesel truck’s emissions reduction system. Nitrogen oxide (NOx) gases are formed in the combustion chamber when heat brings nitrogen and oxygen atoms together. NOx is an ozone which settles at ground level, causing breathing problems, acid rain and smog. The EGR system reduces NOx as it recirculates exhaust gases and mixes them into the air passing through the intake where the dilution of the air/fuel mixture lowers combustion temperatures and reduces the formation of NOx.

The amount of exhaust gases entering the intake is controlled by the EGR valve. With exhaust gas temperatures exceeding 1,200 degrees Fahrenheit, these gases are too hot to introduce directly into the intake, so they pass through an EGR cooler on the way to the intake. These coolers pass the exhaust through a piping chamber connected to the engine’s cooling system. The EGR cooler, an air-to-liquid heat exchanger, uses the circulating engine coolant to lower the temperature of the exhaust gases passing through it. The cold-side EGR valve directs exhaust gases into the intake after they’ve left the EGR coolers.

EGR valves are a point of failure with diesel engines. When the valve sticks, it triggers the Check Engine Light and it decreases power. Replacing only the EGR valve, often times, isn’t all that is needed to protect your engine, because EGR failure is usually caused by problems with other emissions, coolant or lubrication components. If your Check Engine Light is on, Cummins Automotive & Diesel Service can check to see if the EGR valve is at fault and will thoroughly check other components relative to this diagnostic, investigating to determine if other emissions components, the coolant system or lubrication components are at fault.

Variable Geometry Turbocharger (VGT)

Variable Geometry Turbochargers are a crucial component in the reduction of both particulate matter and NOx emissions. In relation to the EGR system, the VGT ensures that positive pressure exists between the exhaust and intake manifold(s) so that sufficient EGR flow is available when it’s needed. Additionally, by functioning like a more restrictive turbo at lower RPMs, its transient response translates into peak efficiency. This responsiveness means that the engine is kept within its power band, where fuel is more efficiently burned.

DOC, DPF, Regeneration, Back Pressure & SCR

Heavy duty diesel pickup trucks and semi trucks use an assortment of exhaust aftertreatment devices, including Diesel Oxidation Catalysts (DOC), Diesel Particulate Filters (DPF) and Selective Catalytic Reduction (SCR) catalysts. The combination of these three devices utilize physical mechanisms and chemical reactions to remove nearly all particulates and harmful gases.

The DOC is a honeycomb ceramic catalyst and it is the first device in the aftertreatment system that the flow of exhaust encounters after it leaves the engine’s manifold. The DOC is a flow through filter that contains precious metals. The gases in the exhaust, upon flowing through the DOC, start the oxidation of hydrocarbons, carbon monoxide, unburned fuel, and oil; it oxidizes NO (Nitric Oxide) to NO2 (Nitrogen Dioxide), and some particulate matter (PM) is removed.

The DPF is the second device in the aftertreatment system and it is a honeycomb ceramic filter, but unlike the DOC’s flow through design, the DPF is a wall-flow filter that traps any soot that remains in the exhaust which the DOC could not oxidize. The soot will remain in the DPF until it is regenerated. With regeneration, the remaining particulates will be oxidized through two different engine temperature elevation processes.

Passive regeneration and active regeneration are the two processes that capably oxidize the particulate matter, or soot. Passive regeneration occurs when the truck’s normal operating temperatures reach between 527⁰ and 680⁰ Fahrenheit. As the DOC oxidizes the unburned diesel fuel in the exhaust it provides the means of increasing the DPF temperature to heat extensive enough to incinerate the soot buildup within the DPF and reduce it to ash. Active regeneration is executed when sensors detect an excessive build-up of particulates within the DPF, at which point, raw fuel is injected into the exhaust stream. The excess fuel triggers engine operating temperatures in excess of 1,112⁰ Fahrenheit.

Regeneration is an important process, because without it soot builds up and the exhaust back pressure can elevate. Regeneration converts the soot to an ash and this usually reduces the backpressure down, close to normal, or at normal. The ash is composed of the minerals, metals and trace elements that result from the oxidized gases and from the breakdown of lubricants and additives. The ash is an element in the exhaust aftertreatment system that will need to be dealt with manually. It is important to periodically remove the DPF to clean the ash out. If it is not cleaned out, it will build up inside the DPF and eventually lead to problems.

Ash builds up at a much slower rate than soot; however, if the buildup is ignored it will eventually cause increased back pressure, excessive fuel consumption and potential DPF failure. The longer the ash is left inside the DPF the greater the chance it has of hardening into a plug which can block a portion of the filter. Additionally, as ash builds inside the DPF the frequency of active regenerations increases, causing poor fuel economy, extremely high temperatures, and can possibly lead to constant elevations in back pressure that can be harmful to the turbo charger.

If you notice your diesel truck is exhibiting shorter intervals between regenerations, it can be a first clue to ash build up and the need to remove the DPF for cleaning. Cummins Automotive & Diesel Service can observe the shorter intervals between regenerations by datalogging the regen cycles in the workshop with diagnostic equipment. If you bring your diesel truck in to Cummins Automotive & Diesel Service, when they remove the DPF for cleaning, they will also remove the DOC and clean it, if necessary.

The SCR catalyst is the third, and last, component in the aftertreatment system. It is a flow through device which introduces Diesel Emissions Fluid (DEF) into the process by injecting a light mist of urea into the hot exhaust stream. The diesel emissions fluid contributes to the further break down of the nitrogen oxides (NOx) that were able to get past the DOC and the DPF, chemically converting them into harmless nitrogen. The SCR catalyst usually does not need maintenance, but Cummins Automotive & Diesel Service will inspect it for those rare occasions in which the component related to the DEF fluid fails.

The DOC, the DPF, and the SCR catalyst all contain ultra-fine filter materials with which they capture the microscopic particulates. A DOC can contain several precious metals, on of which is platinum, which bonds with the oxygen molecules in hydrocarbons. The DPF can contain different materials, but most commonly it will contain cordierite composites. An SCR catalyst contains filter contents in the form of ceramic materials and precious metals. The array of filter materials contained in each device provide a specific composition of metals which play important roles in the chemical reactions necessary to effectively clean the particulates for the reduction of emissions.

DOC, DPF & SCR Maintenance

With time, the DOC, the DPF and the SCR catalyst can become clogged, therefore regular maintenance is important. Cummins Automotive & Diesel Service can quickly locate each device and service them accordingly. Routine maintenance cannot be emphasized enough, because if substantial blockage builds up, it can cause irreparable damage to the exhaust system that can result in excessively high repair costs, unscheduled truck down time, and the release of particulate matter pollution into the environment.

The DOC and DPF can be cleaned using pneumatic and thermal cleaning processes. The SCR catalyst, however, because it is a closed unit, it is not suitable for pneumatic cleaning. The SCR catalyst can get blocked by hardened diesel emissions fluid. If this occurs, it is usually not serviceable, requiring replacement of the SCR catalyst.

Driving Patterns

These filters and catalysts are sensitive devices and they work in delicate balance with each other. They are synced with the engine’s operation and respond to how the trucks are driven. If driving patterns are short and infrequent, the high temperatures necessary for regeneration may not be reached and irreversible damage to the DPF can occur. Trucks that are on the road a majority of their operation time will naturally encounter driving patterns whereby the passive regeneration kicks in regularly, resulting in the expected, longer service duration before maintenance is necessary.

Preventative Maintenance Helps To Ensure Complete Regeneration

Diesel exhaust aftertreatment systems are highly sophisticated emissions systems that need to be properly diagnosed and repaired when the regeneration process fails. Looking for the clues and indicators that regeneration has failed, or that it has processed incompletely, can save truck operators money. Early maintenance and repairs are usually less expensive than replacing the DOC or the DPF when they become compromised beyond servicing.

Cummins Automotive & Diesel Service can check the hydrocarbon doser (HD doser) for proper operation. If the HD doser fails, diesel fuel will not be injected into the exhaust stream and the engine will fail to regenerate.

Cummins Automotive & Diesel Service can check if the DPF pressure sensors are malfunctioning, which will cause the aftertreatment control module or the Engine Control Unit (ECU) to receive false readings and possibly initiate regenerations more frequently than are normal.

Cummins Automotive & Diesel Service can check for any fault codes related to the Exhaust Gas Recirculation (EGR) system. This is an important diagnostic metric to monitor because EGR fault codes can either interfere with the regeneration process or they can cancel a regeneration entirely.

If your truck is operated under conditions consisting primarily of short trips or stop and go traffic, face plugging of the DOC can occur. A plugged DOC is a DOC failure and it will interfere with the regeneration process. Cummins Automotive & Diesel Service can check the condition of your DOC. When a diesel engine is allowed to regularly reach the correct operating temperature, with longer driving/operating durations, DOC face plugging does not occur.

Cummins Automotive & Diesel Service can remove your DPF for the routine service of baking and blowing, or aqueous cleaning, to restore the filter to approximately 95% of its capacity. This routine DPF service will prevent the diesel particulate filter from plugging. A clean DPF is important because clean filters can ensure efficient, thorough regenerations rather than regenerations that last longer with poor results.

Cummins Automotive & Diesel Service can check for faulty temperature sensors. Temperature sensor readings give indications of how the DPF system is operating. Temperature sensor diagnostics are an important part of routine maintenance service because faulty sensors will stop the regeneration process.

Cummins Automotive & Diesel Service can check for early signs of Variable Geometry Turbo failures. Variable Geometry Turbo failures can prevent regenerations from being completed due to a less than optimal heat generation during the regeneration process.

Cummins Automotive & Diesel Service can run complete engine fault codes diagnostics. Engine fault codes can be thrown to indicate the failure of one or more components in the truck’s complete operating system. If one or more components in the system are faulty, they can prevent the regeneration process from occurring. As with faulty temperature sensors, engine fault codes related to emissions, pressures, turbos, boost, and more, can point out components that may need to be tested for proper operation to ensure regenerations are able to be processed.

Cummins Automotive & Diesel Service can run diagnostics on the network of electrical wires, connectors and plugs that run from components to their respective sensors. Faulty electrical wires, connectors and plugs can prevent regenerations just as faulty sensors or components can. When the electrical connecting network contains faults, the sensors may not be malfunctioning but the ECM or other related computers will receive incorrect values due to the wiring harness being defective. Incorrect values received by the ECM or other related computers can prevent full regenerations or initiate incomplete regenerations.