DPF (Diesel Particulate Filter) Solution

Customers may require a software DPF deletion when remapping a vehicle, each case is different and treated accordingly. It is not recommended for road use and inspection of the exhaust system carried out during the M.O.T test will include a check for the presence of a DPF.

What is a DPF?

A DPF (Diesel Particulate Filter), FAP on some French vehicles, is a device fitted to the exhaust system of modern diesel vehicles to reduce emissions and to meet emission standards. It does this by trapping soot from the exhaust gases whilst permitting flow of the gases through the system.
As like 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 like 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 from the exhaust on occassions. When regeneration is taking place you will notice a reduction in fuel economy.
DPF's 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) has tighten this up further.

When is a DPF Solution Required?

• DPF error
• DPF or Limp Home warning lights on your dash
• Poor acceleration and fuel economy
• DPF too expensive to replace
• vehicle no longer requires DPF (off road use)

LEGAL REQUIREMENTS AND THE M.O.T TEST

M.O.T will check for a visual presence of a DPF from February 2014, a missing DPF will result in a M.O.T failure.
A vehicle might still pass the M.O.T visible smoke emissions test, which is primarily intended to identify vehicles that are in a very poor state of repair, whist emitting illegal and harmful levels of fine exhaust particulate. It is an offence under the Road Vehicles (Construction and Use) Regulations Act (Regulation 61a(3)) to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards it was designed to meet.
Removal of a DPF will almost invariably contravene these requirements, making the vehicle illegal for road use. The potential penalties for failing to comply are fines of up to £1,000 for a car or £2,500 for a light goods vehicle.

Problems Encountered with DPF

If regeneration doesn't function properly it leads to a build-up of soot affecting vehicle performance and fuel economy. If left unattended this will result in a blocked DPF which can ultimately cause very expensive damages 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 new 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 2500RPM for approx. 15-30mins at least once a month, this will help keep things working.
Many diesel vehicles are used primarily in urban areas or on short stop start journeys, e.g. local deliveries, taxis, 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 like residue will build up in the DPF and have same affect ultimately resulting in a blocked DPF. For this reason, a DPF is classified as a serviceable item by the vehicle manufacturers, just like brake pads or air filters etc. and not covered under warranty. DPF Systems therefore need to be maintained properly.

What Are My Options?

If the vehicle DPF warning light is on your DPF will already be significantly blocked. Forced regeneration by a garage or a "blast down the motorway" is not likely to cure the problem; these only work as preventative maintenance. So at this stage realistically you have the following options:

• DPF Regeneration - we can offer a regeneration service
• DPF Replacement - we offer a replacement service dependant on vehicle, please contact us
• DPF Cleaning - we offer a DPF cleaning service dependant on vehicle, please contact us
• DPF Recalibration - if you have had your DPF core removed, we may be able to recalibrate your vehicles ECU to stop your engine going into limp-home mode and clear the DPF warning light. Consumers must be aware of the legal implications (as above) of this being carried out.

Why is an EGR Needed?

Exhaust recirculation adds burnt gases into the combustion chamber, reducing the oxygen content present in the air within the chamber. The combustion process now burns at a lower heat release and peak cylinder temperature which results in a reduction in the formation of NOx. The presence of a inert gas in the cylinder further limits the peak temperature.

Diesel Engines - As diesel exhaust gases contain soot particles, when the EGR valve recirculates this gas, the soot can eventually make the actual EGR valve clog and fail, other valves and flaps can fail too (throttle valve, swirl flaps, turbo charger vanes); leading to a costly bill. Newer engines have an EGR cooler built-in, which results in even faster clogging.

Clogged throttle flap, sometimes throttle flaps have tiny holes for airflow, any clogging of these holes can usually produce poor idling issues.	Clogged/Blocked EGR valve, will cause poor engine running and eventually the dashboard engine warning light will turn on.	Clogged swirl flaps in the inlet manifold will cause poor fuel economy and reduced max power/torque.	Clogged Variable Vane Turbocharger will cause reduced max power/torque & engine response leading to limp home mode warning light.	Clogged or soot coated engine sensors will lead to false readings sent back to the ECU (Engine's Brain), leading to poor emissions, fuel economy, reduced max power/torque & engine response.

All the above can be eliminated by switching off the EGR circuit when remapping your vehicle. An EGR valve may give optimum emissions when the vehicle is brand new, but as the miles are put onto the vehicle the above pictures clearly show the benefit is of a limited time period. A switched off EGR valve will run better than any of the above scenarios as it will prevent clogging and soot build up, and finally added cost of repairing/replacing parts.

Petrol Engines - As petrol engines use EGR valves to aid fuel economy at partial throttle to prevent pumping loses, due to this we do not advice customers to change setting on Petrol Engine EGR valves. Should the valves become clogged, we recommend to unclog the vavle or fit a new one, but never switch the valve off as your will experience reduced fuel economy. As future EGR systems evovle using low pressure, cooled and even fast acting EGR systems fuel economy will further improve up to 5%.

EGR Solution

GNRS offer a solution for Diesel EGR Valves only. The valves can become clogged with Carbon desposits, causing them to fail or stick, thereby producing error codes and affecting the vehicle by not running correctly. Our software solution is to disable the EGR valve in a simple and effective method of improving the efficiency of your engine and to avoid costly bills to fix clogged or failed valves and swirl flaps. EGR valve disabled does not reduce fuel economy once the engine reaches optimum temperatures.

What are the Benefits?

• As mentioned above, to prevent clogging and failure of parts, which may lead to engine failure and further expenses.
• Removal of the EGR system by Blanking off the exhaust input and reprogramming of the engine management ECU results in lowered engine temperatures, improved throttle response, economy and also can lengthen engine life by reducing oil contamination and carbon deposits.
• We only advice EGR switch off on Diesel engines only

EGR Configurations

In this section we aim to provide an understanding that remapping and the engine as a whole is a sub-system on how to improve fuel economy. The vehicle can be looked on as a tool on how to achieve better fuel economy. Tips below:

1. Remapping a vehicle can improve fuel economy. Mapping at light throttle yields better results and improved fuel economy in comparison to the manufacturers standard mapping.
2. Fuel Injector cleaning helps maintain spray patterns within the combustion engine. It aids correct fuel atomisation maintaining fuel economy, power and torque. Our Special offer page is giving away a free bottle of Injector cleaner with every remap.
3. The condition of your tyres can greatly affect fuel economy: tyre pressure should be correct; under inflated tyres reduce fuel economy. Using low rolling resistance tyres will further improve fuel economy.
4. Incorrect wheel alignment will cause additional frictional drag between the tyres and road surface. You would be well advised to check and adjust wheel alignment at the correct intervals.
5. Driving a vehicle in a high gear, at low RPM, with light throttle applications and using cruise control at motorway speeds really helps with improving fuel economy, as it prevents unwanted acceleration and deceleration; (use cruise control when it is safe to do so).
6. It is economical to switch off the air conditioning when not needed. When the vehicle requires cooling, you may instead, open windows while driving at low speeds, or, use air conditioning at high vehicle speeds, remembering to turn it off once optimal temperatures are reached.
7. Additional weight within the vehicle will reduce fuel economy. Lighten your load. by removing additional weight which is not required: e.g, remove roof rack, excess items stored in boot, etc.
8. Remembering to service your vehicle at the correct intervals, ensuring service checks of the oil, oil filter, fuel filter, spark plugs (petrol only), all improves the life of your vehicle in addition to economizing on fuel. The use of synthetic oils maximizes engine protection and aids in better fuel consumption.
9. Vehicle aerodynamics - avoid using roof racks. Make sure underbody trays and ducts are in good condition and attached to the vehicle correctly. Ensure windows are closed when driving at high speeds.
10. Check engine sensors with Vehicle Technician's diagnostic equipment; any failed or failing sensors will reduce fuel economy. Request your Vehicle Technician to go one step further and examine any sensors which are working within tolerance conditions, and are appearing to fail: replacing them will aid fuel economy. For example, MAF (Mass Air Flow) and/or oxygen sensors all go out of calibration with use and age of vehicle, as the sensor goes slightly out of calibration fuel economy usually suffers. As part of our remapping service, GNRS offer a free diagnostic check before any remapping.

Diesel Remapping

A Diesel Engine is considered a Compression Ignition engine, the 3rd stroke - compression cycle squeezes the air so much which causes high temperature as a by-product. When the fuel is injected in, the fuel self-ignites. Diesel Engines are a lean burn engine, it always has excessive air within the combustion chambers and more fuel is added to increase torque and power. Included, is a graph which shows the ideal burn mixture within a laboratory - stoichiometric for Diesel is 14.55 parts of air to 1 part of fuel. Unfortunately, a road/street diesel vehicle cannot use this air fuel ratio because 1) excessive black smoke (soot) will come out of the exhaust pipe, 2) Pistons and Turbos will run too hot leading to eventual failure.
If you have ever seen a racing Lorry, it is tuned between stoichiometric (14.55:1) and the Smoke Limit (16:1) which is far too much smoke/soot for road use, plus the engine will not last long due to excessive turbo and piston temperatures. Original Manufacturers Equipment (OEM) tend to tune a Diesel Engine at full throttle towards 20 to 22 parts of air to 1 part of fuel (green on graph) approx. The graph below shows further fuel can be injected into the combustion chamber to produce more power without reaching the smoke limit. When remapping the target used for full throttle is around 17 to 19 part of air to 1 part of fuel approx which is still below the smoke (soot) target limit. The smoke limit is around 16 parts of air to 1 part of fuel. On Turbo Diesels the boost pressure is increased slightly to provide extra air into the combustion chamber and further fuel can be added to maintain around 17 to 19 part of air to 1 part of fuel mixture, which leads to extra power and torque. When tuning on the Rolling Road we always check for Exhaust Gas Temperature (EGT), too hot will reduce engine life or failure, we never want extra power at the expense of running too hot EGT. Never choose a remapping Company who do not programme on the rolling road. All GNRS Remaps have been carried out on the Rolling Road using a test Vehicle which would be the same as the Customers vehicle. The test vehicles remap data will then be used on the Customers Vehicle ECU.

Petrol Remapping

A Petrol Engine is known as a Spark Ignition Engine, a spark plug is used to ignite the fuel/air mixture. Included is a graph which shows the ideal burn mixture within a laboratory - stoichiometric for Petrol is 14.7 parts of air to 1 part of fuel. As a general statement when tuning for power, the engine prefers to see a richer mixture than stoichiometric. Air Fuel Ratios of 12.5 air to 1 parts of fuel is used, sometimes with Turbocharged engines, the ratio can go up to 10 parts of air to 1 parts of fuel. Petrol engines when run rich have the ability to run as a cooling agent: it cools the engine, cylinder head, valves and pistons.
When tuned for fuel economy Air Fuel ratios can be around stoichiometric to 16 air to 1 parts of fuel, this is dependent on if the Vehicle uses a Cataytic Converter or not, if it does then stoichiometric is better for maximum catalytic efficiency. EGR Valve open helps with fuel economy by reducing the oxygen in the combustion chamber thus reducing the fuel content to achieve stoichiometric air fuel ratio.
Original Manufacturers Equipment (OEM) tend to tune a Petrol Engine at full throttle with conservative air fuel ratios, when remapping we add extra fuel (remember rich mixture also acts as a coolant). With Turbocharged engines boost pressures are increased and further fuel added to achieve the correct air fuel ratio. At the same time we remap the ignition timing to produce Minimum Advance for Best Torque. If High Octane fuel is used ie from unleaded to super unleaded then further power can be achieved as more ignition advance can be dialled in. The Engine Control Unit (ECU) can normally recognises this fuel via its sensors, it can optimise the fuelling and ignition timing to provide more torque and power.
When tuning on the Rolling Road we always check for correct air fuel ratios (using external lambda sensors) and any detonation or pre-ignition (using external knock detection sensors), any pre-ignition or detonation will cause engine failure, we never want extra power at the expense of going into this zone. On some applications, we may recommend using cooler spark plugs to prevent pre-ignition or detonation. Never choose a remapping Company who do not programme on the rolling road. All GNRS Remaps have been carried out on the Rolling Road using a test Vehicle which would be the same as the Customers vehicle. The test vehicles remap data will then be used on the Customers Vehicle ECU.
As a general statement for Petrol engines, the tuning option is Red (extra power with no fuel economy improvement), 99% of Petrol Vehicles in Western Europe use a Catalytic Converter, which needs a air fuel ratio of stoichiometric 14.7 parts of air to 1 part of fuel, any leaner and the Catalytic Converter will not work correctly (NOx levels will not reduce). Therefore at light throttles when tuning for fuel economy we aim for stoichiometric 14.7 parts of air to 1 part of fuel.