Factors in Diesel Particulate Filter Clogging

Diesel Particulate Filter (DPF) trouble, primarily clogging, is usually caused by insufficient exhaust temperatures during regular driving, leading to incomplete soot burning during the regeneration cycle (regens). Other factors include poor fuel combustion due to low compression, sticky rings and glazed cylinder walls, less-than-ideal maintenance, incorrect engine oil, low fuel quality, and engine or sensor problems.

Insufficient Exhaust Temperatures:

Short Trips:

Large trucks waiting at a Port

Long idle times, short trips and low-speed driving all contribute greatly to DPF clogging

Frequent short trips and low-speed driving prevent the engine from reaching optimal operating temperatures. This causes inadequate and incomplete combustion of the fuel, creating excessive soot buildup, which in turn hinders a successful regeneration process.

Long Idle Times:

Prolonged idling also results in deficient combustion of the fuel. As expected, this also causes excessive soot production and accumulation, which adversely affects the effective operation and regeneration of the DPF. Glazed cylinders are also a quick result of long idle times. Idling also decreases exhaust temperature; not a good thing for DPF functionality.

Shoddy Maintenance:

Lack of Regular Servicing:

DPF and associated issues can be reduced with regular oil changes and oil-system flushes

Neglecting scheduled maintenance and essential adjustments can quickly lead to low engine performance and increased emissions. Ensuring valve timing (whether VVT or conventional) is correctly set and operating accurately, checking valve clearances are within specs, as well as confirming injector timing and function are on track, are all vital to ensuring efficient engine operation and reduced DPF problems.

Using Incorrect Engine Oil:

Using low-quality, non-engine-specific engine oil, particularly oils with high ash content, can rapidly accelerate DPF clogging. Ash is the primary bonding agent for soot particles within a DPF. Non-low-ash oil can be responsible for up to 90% of DPF clogging issues. Accordingly, using correct, low-ash engine oil significantly reduces DPF clogging and frequent regen problems. API CK-4 spec denotes low-ash oil (1%); some oils have ultralow-ash spec (≈0.5%). Irregular oil changes and oil-system flushes both contribute to DPF and associated issues.

Exhaust Gas Recirculation (EGR) Valve Problems:

Badly blocked diesel engine EGR

EGR carbon buildup is usually due to heavily sooted exhaust gases - caused by incomplete fuel combustion

A faulty EGR valve can cause excessive soot production and consequently become another contributing factor in DPF problems.

A faulty EGR valve in a diesel engine is most often created by carbon buildup, often from heavily sooted exhaust gases caused by incomplete fuel combustion. Poor fuel quality can be a covert contributor to this problem, as well as low compression.

Carbon buildup problems occur when carbon/soot particles are deposited over time on critical EGR components. These include the air intake system, pipes, the valve and valve mechanism, and temperature sensors.

Faulty Fuel Injectors:

When fuel injectors are not functioning correctly, incomplete combustion and increased soot production are usually the result. Soot will subsequently accumulate in any one or all of these places – the DPF, turbocharger, EGR, the combustion chamber including rings, ring grooves, and cylinder walls, and the engine oil (turning it black, thick and gritty).

Good vs Bad diesel injectors

Ensure fuel injectors are clean and operating correctly to enhance fuel combustibility

Faulty injector symptoms can include:

  • Increased fuel consumption
  • Rough idle
  • Misfire
  • Poor engine performance
  • Hard starting
  • Exhaust smoke
  • Noisy engine

Turbocharger Issues:

Faulty turbocharger

Numerous turbocharger problems can be avoided by using preventative measures

A failing turbocharger can leak oil into the exhaust system, causing excessive soot and DPF clogging.

Common causes of turbocharger oil leaks:

  • Worn Seals and Gaskets: Leaks occur as the seals and gaskets within the turbocharger deteriorate over time.
  • Blocked Oil Return Lines: Oil can back up and leak out of the turbocharger's compressor or turbine end if the oil drain line is blocked (often sludge build-up) or kinked.
  • Excessive Crankcase Pressure: Often, stuck or worn compression rings and glazed cylinders, or PCV system issues, will cause high crankcase pressure. This adverse condition can force oil through seals and into the turbocharger. Faulty air compressors can also create excessive crankcase pressure.
  • Improper Installation or Setup: If the turbocharger is not installed correctly, or if the oil lines are not sized appropriately, it can lead to internal leaks.
  • Other Factors: Conditions like repeated hot engine shutdowns, excessive idle time, or even blockages in the air intake system may contribute to internal oil leaks.
  • Physical Damage: Damage to the turbocharger’s housing or internal components can also lead to leaks occurring.

Faulty Sensors:

Several problems can arise because of faulty sensors

Faulty sensors can severely disrupt DPF operation by hindering the engine computer's ability to accurately monitor and control the filter's performance. This can lead to issues like inaccurate regeneration cycles, premature clogging, and reduced engine performance.

Some of the related sensors include:

  • Differential Pressure Sensor
  • Exhaust Gas Temperature Sensor
  • EGR Valve Position Sensor
  • Soot Sensor
  • Oxygen Sensors

Other Factors:

Simple things can often be overlooked, which can lead to clogged DPFs

Fuel Quality: Using low-quality fuel, which often triggers reduced fuel combustibility, can increase soot production and DPF clogging.

Clogged Air Filter: A clogged air filter will restrict airflow, disrupting the air-fuel ratio in the combustion chamber, leading to incomplete combustion and increased soot production.

Overloaded DPF: If the DPF is overloaded with hard, baked-on soot, it can crack or melt, reducing its efficiency or causing complete failure.

Here are some fundamental Pro-active Maintenance steps you can take right now that will significantly reduce the likelihood of DPF (and other problems) with your diesel engine.

FTC Decarbonizer is a truly unique combustion catalyst. It oxidizes hard carbon and soot from all combustion and exhaust spaces, including turbos, EGRs and DPFs at much lower temperatures than usual. It makes fuel combust much faster, easier and more completely. It will remove hard carbon from compression rings and grooves and deglaze cylinder walls of cross hatch carbon buildup. Forced DPF regens are significantly reduced or entirely eliminated. Power is restored, fuel economy is increased, soot and other harmful emissions are reduced, and engine life is prolonged.

ULS Diesel Enhancer safely and effectively removes all diesel injector and fuel pump deposits, restoring correct injector spray pattern and freeing sticky injectors. It disperses contaminants as they form, and boosts today’s Ultra Low Sulfur Diesel fuel lubrication properties. Adding it to diesel will restore power and economy, boost diesel fuel lubrication properties, provide exceptional anti-rust protection to fuel pumps and injectors, and extend the operational life of injectors and fuel pumps. It is a total high-pressure fuel system treatment.

Flushing Oil Concentrate is a remarkable product and is possibly the most effective treatment in removing harmful and performance-draining sludge, hard carbon and other damaging contaminants and deposits from oil-wetted engine components. Piston oil-control rings are de-sludged, oil return lines are unblocked, oil pump pressure valves are cleaned, soot and carbon combustion by-products are reduced as oil control is restored. Engine component life and effectiveness are greatly extended as the engine oil can remain truly clean and viable between regular service periods.

Stop Smoke Diesel Pack includes all 3 products, and represents a price saving over if the products were ordered individually. Available in 5 different size packs depending on your need.