Diesel engines much like petrol ones might operate similarly, but when it comes to burning fuel, things are a bit different. A diesel engine creates a lot of soot during its combustion process, hence why vehicles like your Hilux have what is known as a diesel particulate filter. This filter is part of your Hilux’s exhaust system responsible for preventing harmful particles from exiting out of the vehicle and into the air thus help lower air pollution.
Although a DPF was first used in a 1985 300D Mercedes, the requirement for every diesel vehicle to have one as a mandatory component didn’t come until 2009. This made it illegal for manufacturers to make diesel vehicles such as the Hilux without a DPF but it also made people venture more into making the most out of this new part. A DPF, much like an ashtray needs to be emptied – the ash being the soot that accumulates over time causing all sorts of issues if it blocks the filter.
When a DPF is going bad or getting clogged you will hear the engine note change and cooling fans start to run more aggressively. Your Hilux will have a slightly increased idle speed and fuel consumption too while a hot acrid smell will be coming from the exhaust. This isn’t a bad thing though, it just means that your DPF Hilux is going through a process known as active regeneration.
This process happens when your Hilux’s ECU (engine control unit) detects that the DPF is getting full of soot and thus starts injecting extra fuel into the engine so that it raises the temperature. By raising the temperature inside the engine, active regeneration is triggered which takes about 15 minutes – usually enough time to burn the soot off the filter. If this process were to be interrupted your vehicle would encounter certain issues, otherwise the process itself shouldn’t affect the operation of the vehicle since its designed to take place whilst you’re using it.
Active regeneration usually happens when you’re vehicle has passed anywhere between 320 km and 480 km. The speed of the moving vehicle usually needs to be above 60 km/h for this process to take place and you should be on the motorway so it’s continuous too. Your DPF Hilux will alert you when this process is about to happen with an orange warning light. If you were to ignore the warning light on your dashboard the vehicle would usually continue into what is known as “limp” mode. Sometimes this mode can be activated by other factors too but you’ll know when its because of an incomplete regeneration process since your vehicle will be super active during it. There’s also another type of process called passive regeneration that is far more convenient.
By convenience I mean less work on your side and more on the vehicle itself. Whilst passive regeneration also needs to take place on the motorway, it isn’t as demanding as active regeneration. If you are someone who is frequently driving your Hilux in the city it is wise to take it for a solid 30 to 50 minute spin on an A-road when you can. This will help clear the filter off any soot and it rids you from having to do an active regeneration whenever your vehicle needs it.
Passive regeneration happens on your own accord which in a way is better since it rids your filter too, from the soot that will otherwise stay inside it for longer. Active regeneration can significantly dilute the engine oil during what are known as the post-injection cycles which is why passive regeneration is preferred. Whilst this can vary from one make and model to another it is best to avoid it as much as you can.
If a blocked DPF is not getting unclogged by active nor passive regeneration DPF cleaning needs to happen. This is the most effective way to clean your Hilux DPF filter and it’s done with the help of a process called flash cleaning. Not only does flash cleaning remove built-up soot and exhaust residue but it also helps increase economy and performance. Flash cleaning is capable of completely removing PM10 residue trapped in the filter as well as cerium and oil. To maintain the safety of the filter the best route is to go with a flash cleaning. There is one more method used for DPF cleaning, called ultrasonic.
The ultrasonic method is deeply effective as it is a treatment that can clean even the filter cells. While it’s super effective, the ultrasonic method is known to damage the filter since it causes a lot of vibrations and if your Hilux has a big filter, the process won’t be as effective as flash cleaning. Some suggest that adding chemicals can help clean off the filter but these chemicals are more often ineffective and are known to leave more residue than there is thus blocking your filter furthermore.