Dinex Emission: The Solution to Diesel Pollution

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Dinex Emission is a company that has been dedicated to helping diesel operators meet the high standards of the EPA for a very long time. Though the EPA’s goal is to reduce the emissions of dangerous gasses into the air, their restrictions can often make transporting goods, completing construction projects, and harvesting large crops more difficult. As an expert in the field of diesel emissions control, Dinex has long been the solution to this obstacle.

Dinex Emission: Helping Diesel Operators Meet EPA Regulations for Years

What’s in a Name? The Importance of Parts You Trust

The EPA is a regulatory government entity that can and will fine organizations that do not comply with the environmental regulations that are set. These fines are not small and are designed to affect the bottom line of any company they are levied against.

Understanding the Diesel Emissions Systems

The three main components that we will discuss here are the DOC (Diesel Oxidation Catalyst), the DPF (Diesel Particulate Filter), and the SCR (Selective Catalytic Reduction).

• The DOC heats up the gases that pass through it so it can burn off the soot that is built up in the Diesel Particulate Filter, which is the next stage.
• The DPF’s job is to trap particulate matter in the way of soot so it doesn’t come out of the exhaust.
• NOx sensors are located at the turbocharger outlet and the tailpipe of the SCR to measure the amount of oxygen and NOx in the exhaust flow. This helps regulate how much DEF (Diesel Exhaust Fluid) needs to be injected to eliminate the NOx gas before the exhaust is released.

Note: DEF (Diesel Exhaust Fluid) contains a combination of urea and de-ionized water that’s injected into the exhaust stream of diesel engine vehicles to turn NOx gasses (harmful emissions) into nitrogen and water (non-harmful gasses).

What is DPF Regeneration?

There are two types of DPF Generation; Passive and Active.

• Passive Regeneration (also known as “free” regeneration) happens when the exhaust is heated naturally in a high-duty cycle with assistance from the DOC to burn off soot built up in the DPF.
• Active Regeneration (also referred to as “paid” regeneration) happens when fuel is injected into the DOC to artificially boost regeneration temperatures to burn off the soot buildup in the Diesel Particulate Filter.

Why Does a DPF Need to be Cleaned?

During the process of releasing exhaust from the engine, soot and ash build up in the Diesel Particulate Filter to prevent it from being released into the air. Soot is removed by one of the regen processes. Ash is a byproduct of burning oil and is noncombustible so the regen process doesn’t eliminate this substance from the DPF. The presence of ash buildup causes two main issues: it increases back pressure which decreases engine power and reduces efficiency. It reduces the capacity to retain soot. Cleaning the ash from the filters on a schedule ensures that your truck continues to run clean at maximum performance.

DPF Cleaning Timelines

A DPF filter should last anywhere from 2 to 3 cleanings before it needs to be replaced due to age, wear, and tear.

Recommended Cleaning Schedule for a DPF:

• Long Haul Trucks – Every 200k to 250k Miles.
• Local Stop-and-Go Trucks – Every 100k to 150k Miles.
• Severe Duty Truck – every 75k to 100k Miles.
• Transit (Buses), Garbage Trucks, and other High-Idle Diesel Vehicles. – Every 50k to 75k Miles.

When is it Time to Replace DOCs and DPFs?

Knowing when to replace your emissions components is just as important as knowing when to have them serviced and cleaned. A defective DOC or DPF can negatively affect how your diesel engine performs. They reduce your horsepower and efficiency which can both impact your bottom line.

Let’s Check Out Your DOC and DPF:

• Make sure your DPF matches the physical integrity and characteristics of a properly functioning DPF core.
• Inspect for signs of soot or black/burn holes on the clean side of the DPF.
• Inspect the DPF for discoloration that appears in the form of rings or circles. This can indicate that there’s a melted core.
  • This is often a sign of excessive fuel, soot, or oil which can cause an uncontrolled regeneration.
• Inspect the DPF for chips, cracks, dents, or bent rims.
• Inspect the DPF core to see if it’s loose. This may be referred to as a “packing failure.”
• Finally, inspect the DPF for signs of fluid leakage like oil or coolant, rust, or chemical stains.

Note: Other things to look for include black soot on your exhaust pipe or stack, ECR coolant leaks or blown turbos that leak oil into the exhaust stream can damage the DOC and DPF. Regeneration that is abnormally active or more frequent than usual, even after a service and cleaning is a good sign that your DOC and/or DPF are not functioning properly.

What if My DPF Fails? Ask These Questions:

• Has the DPF been cleaned on schedule?
  • Based on how your diesel engine is used, has the maintenance schedule been adhered to?​ If not, it’s likely the time to replace the DPF if it’s beyond cleaning.
• How many times has the DPF been cleaned?​
  • 2-3 times is the normal longevity.
• How long after replacement/cleaning did the DPF fail?​
  • These parts can fail or be defective.
• Was the DPF “packed with soot”?​
• Is the DPF damaged?
  • If you find a dent or gouge in the filter face that is more than ⅛’ deep and covers more than 20 cells the DPF should be replaced.
• Was the DOC “Face plugged”?  Was it cleaned or replaced?​
• Were there any upstream failures in the past?  What was done?​
  • 89% of DPF failures were due to upstream issues (clogged filters and low fuel pressure are a couple of examples.)
  • Is the oil changed based on mileage or engine hours?
  • A sign of an upstream failure is a DPF face clogged with soot.
• After treatment history… What was the frequency of active regenerations​?

What if the Regeneration Won’t Complete?

There are several possible causes for a regen to not complete, whether it’s passive or active. If the soot in your DPF isn’t getting cleared through one sort of regen or the other, check for these possible issues.

• Misassembled wiring harness​ – this can cause malfunctioning in the electronic systems or prevent it from working at all.
• Face plugged DOC​ – if the DOC face is plugged it won’t be able to assist in heating the exhaust to burn off the soot during regen.
• A malfunctioning turbocharger​ – this can cause oil to leak into the exhaust system causing damage to the DOC and DPF.
• Exhaust leaks between the engine and the aftertreatment​ – exhaust leaks need to be fixed so it doesn’t escape prior to the emissions control devices.
  • Fluid stains on the DPF outlet is a sign of these leaks and the DPF needs to be replaced.
• Very low ambient temperatures less than 0°F​ – low temperatures in nature can prevent the DOC from getting hot enough to burn off the soot in the DPF.
• Aftertreatment exhaust gas temperature sensors installed in the wrong location – if these sensors are in the wrong location then they will not provide the proper temperature readings needed to engage the regen process.

Note: A regeneration that will not complete can be caused by malfunctions in the exhaust gas recirculation (EGR), variable geometry turbocharger (VGT) systems, or fueling. These malfunctions do not allow the aftertreatment to reach the necessary temperatures for aftertreatment fuel injection. When performing a stationary (parked) regeneration, monitor the following parameters to determine why a stationary (parked) regeneration will not complete:​

• EGR Differential Pressure​
• EGR Valve Position Measured (Percent Open)​
• Exhaust Gas Pressure​
• Intake Manifold Pressure​
• Percent Load​
• Turbocharger Actuator Position Measured (Percent Closed)​
• Turbocharger Speed

What is the Best Preventative Maintenance on DPFs and DOCs?

• Frequent regen code?
  • Are you using coolant or oil? 
  • Do you have any other codes?​
• Do you have black smoke venting from your stacks?​
• Look at the regen history, how often does the regen occur and what are the temps?​
• Does the engine have an aftertreatment fuel injector?
  • Has it ever been replaced?​
• After the root cause of a DPF/DOC failure is identified and repaired (ex. blown turbo, EGR cooler, fuel injectors, etc…) the aftertreatment system should be inspected/tested.

What Causes Frequent Regens in a Diesel Engine?

If your diesel engine is trying to run regenerations to clear your DPF too frequently you could be experiencing one or some of the below issues.

• Air intake system restricted​
• Leaks in the intake air system (a bunch of small leaks equals one big leak, if you find a leak and fix it confirm that you don’t have more)​
• Aftertreatment DPF differential pressure sensor stuck in-range​
• Leaks in the exhaust system​
• Plugged EGR differential pressure sensor supply ports​
• Aftertreatment DPF differential pressure sensor tubes plugged​
• Turbocharger is malfunctioning​
• Aftertreatment Diesel Particulate Filter Regeneration Analyzer Test​
• ECM calibration revision history check​
• Oil usage, carbon-packed piston rings ​
• Weak injectors (ISB uses cylinders 1-3 instead of an aftertreatment injector)​

SCR and DEF Doser Failures

SCR failures can encompass a wide range of subjects. Catalyst contaminants such as engine oil, coolant, or other impurities can damage the SCR catalyst, reducing its efficiency in converting NOx into harmless gases.​ DEF is injected into the exhaust to help the SCR system function. Issues with the DEF system, such as clogged lines, malfunctioning injectors, or low DEF levels, can lead to incomplete NOx reduction.​ Using low-quality or contaminated DEF can lead to deposits forming within the system, affecting its performance. Make sure you service your DEF filter.​ NOx sensors monitor the level of nitrogen oxides in the exhaust gasses. If these sensors malfunction or become contaminated, the system may not effectively regulate the DEF injection, leading to poor NOx reduction.​

Additional SCR Failures include:

• Temperature Sensor Problems: Temperature sensors are crucial for regulating the SCR system’s operation. If these sensors fail, they may not accurately detect the exhaust gas temperature, impacting the efficiency of the SCR process.​
• Software or Control Module Issues: The SCR system’s control module or ECM/ACM software can encounter glitches or failures, affecting the overall performance of the system.​
• Exhaust Leaks: Leaks in the exhaust system before the SCR components can introduce additional oxygen into the exhaust stream. This can interfere with the SCR process and reduce its effectiveness.​
• ​Catalyst Deterioration: Over time, the SCR catalyst can degrade due to exposure to high temperatures and other factors. This can lead to reduced NOx reduction capabilities.​

NOx Sensor Failures and Diagnostics:

• If your EGR System fails, this can introduce a coolant leak into the exhaust system. The best way to diagnose this is an EGR pressure test to see if it’s holding the appropriate pressure.
• If your turbocharger has an internal oil leak this could damage your DOC and DPF. Check your turbo and air filter for evidence of leaks.
• Check your DPF for breaks or cracks in the outlet. If damage is discovered, this cannot be repaired and the part must be replaced.
• If your DEF system is showing crystallization, you may need to replace your DEF heater and/or the DEF injector. You should also make sure you have quality DEF, check that the DEF pressure is good, and that you have a clean DEF filter.

Where Do I Find Dinex Emissions Parts?

HHP is a proud supplier of Dinex Emissions parts and components. We carry Dinex DPFs, DOCs, and OneBox solutions for all of the major diesel engine manufacturers, including Caterpillar, Cummins, Detroit Diesel, Mack, Volvo, Mercedes, Navistar, and Paccar. If you need help finding the right emissions parts for your truck or heavy-duty equipment, contact HHP today and see how we can help you get your diesel engine running again.