The reputation of diesel engines may have gone down quite a bit in recent years but its great benefits, especially with bigger vehicles have made it the perfect candidate for towing and high-torque applications. Diesel engines, unlike petrol engines, rely heavily on high compression and not on spark plugs.
While air is still being introduced to each combustion chamber, it is the level of compression that ignites the fuel not a spark. In colder climates, diesel engines have an ace up their sleeve and those are glow plugs. This and the compression ratio of a diesel is what makes it so efficient.
DPF
What is it
Although diesel engines don't make use of spark plugs they do make use of other components and one of them is a DPF. A diesel particulate filter may not be found on the engine itself, it's still found on diesel cars. A DPF exhaust system is mandatory for all diesel vehicles made from 2008 onwards and they help reduce CO2 emissions without affecting performance that much.
How it works
DPF filters do their magic by collecting the soot created from the ignited diesel fuel that would otherwise exit out in the air. The harmful particles are stored in the component itself and thanks to a ceramic mesh these particulates are trapped in the filter itself without being taken away by the engine fumes coming through. This is why a diesel car needs to be taken on long journeys weekly in order to remove those trapped particles in a process known as regeneration.
DPF Regeneration
Active
A more “straight to the point” DPF regeneration process is an active or manual regeneration that involves more fuel being injected into the exhaust. This increases working temperatures which are needed to burn off the soot. In this case, you get a warning light on the dashboard that tells you to continue driving for a certain amount of time above a certain speed. If you were to interrupt the process in any way this can be bad for the filter which is why manufacturers have made active regeneration possible by the press of a button.
Passive
With a passive DPF regeneration, you get a process that goes on in the background which you can't initiate or stop. In fact, a passive regeneration takes place when certain sensors in the car detect that you're on a longer trip and then a warning comes on the dashboard that the process has started. This can be bad as it the process won't stop even if you park somewhere but it will make sure the DPF is cleaned off especially if it's about 45% clogged up.
What Causes DPF Issues?
EGR Valve
Like any component in any car, a DPF exhaust component is prone to issues that interestingly enough are caused by other components. One of these components is the EGR valve. This component is found on both diesel and petrol engines but diesel engines suffer more from it since it recirculates exhaust gasses.
Since these gasses are more noxious in a diesel engine an EGR valve can get clogged more easily than one in a petrol engine. A defective EGR valve can also affect performance and the way your engine behaves and sounds when idling. This, in fact, makes your car less environmentally friendly as both the EGR valve and DPF filter are not working as they should.
Oil
Using the right oil is key to premature DPF failure and regeneration which is why you should go for low-ash synthetic oils with the correct viscosity grade for your vehicle. It's also important to do oil changes on time as this prolongs the life not only of the engine but the DPF too.
Fuel Injectors
Clogged or defective fuel injectors can also be the cause of a faulty DPF filter and while this is not as common on newer diesel engines, older ones are more prone to it. Faulty injectors are mainly the result of a defective high-pressure pump if it's a common rail diesel engine or using fuel with a low cetane rating which can clog the injectors. A fuel filter that isn't replaced on time or a low-quality one can also cause issues with the injectors.
Turbo
Since all diesel cars and most early 2000s models come with turbochargers either on the side or at the back of the engine, you should be sure to take care of it too. That's because a bad turbo can make for bad DPF filters. Both a faulty turbocharger and DPF are expensive repairs and if you don't treat one the way you should it can make the other act up and essentially make your engine run like an old clunky diesel from the 80s.
Conclusion
Unfortunately, stricter emission regulations are put in place as years go by which is not as good for performance or your pocket as more complex components are added especially to diesel engines. Luckily, proper maintenance and driving in a civil manner can help delegate that.
