DPF Solution
A DPF (Diesel Particulate Filter) also known as FAP on some French vehicles, is a device fitted to the exhaust system of modern diesel vehicles to reduce emissions and meet European emission standards. It does this by trapping Soot (Particulate Matter – PM) from the exhaust gasses while letting the gasses flow through the system.
As with any type of filter a Particulate Filter needs to be cleaned regularly to function properly. With DPF’s this is done by a process known as Regeneration which involves a combination of a Catalyst function in the system and burning the soot to gas at a very high temperature leaving behind an Ash residue within the DPF. Regeneration should be an automatic process taking place in the normal use of your vehicle, you may have noticed this in the form of a blast of white smoke form the exhaust on occasions.
DPFs have been in common use in passenger cars and light commercials from around 2003 in preparation for Euro 4 regs (2005), with Peugeot, Renault and BMW being early takers. Euro 5 (2009) made it compulsory for diesel cars and light commercials to have a DPF fitted and Euro 6 2014 will tighten this up further.
Problems Encountered with DPF's
If regeneration doesn’t function properly it leads to a build up of soot affecting performance and fuel economy, left unattended this will result in a blocked DPF which can ultimately cause very expensive damage to other engine components. A blocked DPF is also potentially dangerous as it can cause overheating in the exhaust system and cause a fire risk. To prevent this damage most newer vehicles will go into “Limp Home” safety mode at this stage, meaning the vehicle will have minimum power barely sufficient to crawl home. For regeneration to take place it requires the vehicle to be driven regularly at some speed on open roads e.g. motorway driving, typically driving at around 2500 RPM for approx 30mins at least once a month, this will keep things working. However, many diesel vehicles are used primarily in urban areas or on short stop start journeys e.g. local deliveries, taxi’s, school runs etc and many have auto gearbox, so the vehicle does not get the chance to heat up sufficiently and is unable to carry out a full regeneration process.
Even if the regeneration functions as it should, over time the Ash Residue will build up in the DPF and have the same affect ultimately resulting in a blocked DPF. For this reason a DPF is classified as a Serviceable Item by the vehicle manufacturers like brake pads or air filters etc and not covered under warranty. DPF systems therefore need to be maintained properly.
The Process
Our fully trained technicians are fully trained and provided with all the latest equipment to effectively diagnose DPF faults and determine the most appropriate solution. Dependent on the fault, the length of time that the fault has been apparent and the vehicle, the technician will be able to use the correct equipement to carry out a forced regeneration, clean the DPF or something more bespoke.
Cleaning or replacing the DPF from your vehicle is not only a cost effective solution but it also boasts the following advantages over living with DPF faults:
- Increased Performance
- Increased Efficiency (MPG)
- Less Turbo Lag
- Reduced Maintenance Costs
What is EGR
A widely adopted route to reduce NOx emissions is Exhaust Gas Recirculation (EGR). This involves recirculating a controllable proportion of the engine’s exhaust back into the intake air. A valve is usually used to control the flow of gas, and the valve may be closed completely if required.
The substitution of burnt gas (which takes no further part in combustion) for oxygen rich air reduces the proportion of the cylinder contents available for combustion. This causes a correspondingly lower heat release and peak cylinder temperature, and reduces the formation of NOx. The presence of an inert gas in the cylinder further limits the peak temperature (more than throttling alone in a spark ignition engine).
A widely adopted route to reduce NOx emissions is Exhaust Gas Recirculation (EGR). This involves recirculating a controllable proportion of the engine’s exhaust back into the intake air. A valve is usually used to control the flow of gas, and the valve may be closed completely if required.
The substitution of burnt gas (which takes no further part in combustion) for oxygen rich air reduces the proportion of the cylinder contents available for combustion. This causes a correspondingly lower heat release and peak cylinder temperature, and reduces the formation of NOx. The presence of an inert gas in the cylinder further limits the peak temperature (more than throttling alone in a spark ignition engine).
The gas to be recirculated may also be passed through an EGR cooler, which is usually of the air/water type. This reduces the temperature of the gas, which reduces the cylinder charge temperature when EGR is employed. This has two benefits- the reduction of charge temperature results in lower peak temperature, and the greater density of cooled EGR gas allows a higher proportion of EGR to be used. On a diesel engine the recirculated fraction may be as high as 50% under some operating conditions.
Here at Maltech Garages we have a very advanced solution for EGR faults. EGR valves can become clogged with carbon deposits, causing them to fail or stick, which in turn leads to error codes and poor running. We have solutions that are used to effectively diagnonise and repair EGR faults, a simple and effective method of improving the efficiency of your engine.
Modern engines recirculate some of their exhaust gases back into the engine with the aim of reducing emissions. This is the is the main benefit of the EGR system. The downside is that exhaust fumes containing carbon deposits are constantly being recirculated through the engine through time causing a build-up of carbon deposits in the intake manifold etc.
These deposits sometimes contribute to the failure of the EGR system itself. Replacement EGR valves can be expensive and in the case of high mileage engines the continual carbon build up can eventually lead to total engine failure.
Cleaning or repair of the EGR system results in lowered engine temperatures, improved throttle response and economy; and can lengthen engine life by reducing oil contamination and carbon deposits.