A Good DPF Explanation

Categories: Chip Tuning

Understanding DPF (Diesel Particulate Filter) Regeneration

Benefits of understanding of the DPF system

  • Easier to explain the system to your customer
  • Help your customer avoid “Limp Home mode”
  • Save your customer time and money
  • Able to quickly and knowledgeably answer questions
  • Helping your customer have a worry free ownership
  • Repeat sales

The variable nozzle turbocharger with charge air cooler and the common rail fuel system reduced nitrogen oxide (NOx) and particulate matter (PM) emissions. In addition, the EGR system helps to reduce NOx dramatically. However, it is not possible to meet the new emission regulations with only these devices. Therefore, 2007i / 2008 model diesel engines have a newly adapted Diesel Particulate Filter (DPF) system which will reduce PM dramatically.
07 EPA PM: 0.133 → 0.013 g/kw-h NOx: 2.66 → 1.62 g/kw


DPF assembly cut-away
Exhaust Flow (inlet)
Oxidization Catalyst
DPF / Muffler / Diffuser Assembly
DPF and Oxidization Catalyst
Diesel Particulate Filter
Diesel Particulate Filter

Particulate Filter Basics

  • The Filter is a Series of Dead End 
  • Exhaust is Forced Through the Wall to an Exit Channel, Which Traps the Soot.

Particulate Filter Basics

Particulate Filter Operation

  • Particulate Matter is Trapped in the Exhaust “Filter”
  • Filter Will Become Restricted and Will Need to be Cleaned or “Regenerated”
  • Particulate Matter Begins to Burn at 600o F (300o C)
  • Regeneration is the Process of Raising Exhaust Temperature to Burn Off Accumulated PM
  • Highway Driving and High Engine Load Results in Lower Accumulations and High Exhaust Temperatures
  • Idling and Low Speed / Low Engine Load Creates More PM

How Does the DPF Clean Itself

  • Fuel injector operation during DPF regeneration:
  • Previous models employed Pilot and Main Injection
  • 2007+ model vehicles use a combination of :

Pre Injection
Pilot Injection
Main Injection
After Injection
Post Injection

Chart explains this clearly


DPF Ash Removal

Many manufacturers recommend a periodic OFF VEHICLE Ash removal process by having the DPF cleaned in a special DPF cleaner @ 120,000 kms or 3,000 hrs of use, whichever occurs first.
However, our experience is that this cleaning “solution” rarely works and is a short term fix at best.  Most replies from the cleaning company are that the DPF is fine and now cleaned.  Shortly after refitment the DPF is again blocked up and you have wasted the amount that was spent on “cleaning” the DPF.
Typical Ash Cleaners
Ash cleaner
Ash remover
if you want to learn more about DPF lamp please click DPF Lamp and Switch Identification