An EGR valve, or exhaust gas recirculation system is a primary component of an engine’s emissions system on both petrol and diesel powered vehicles. Its purpose is to reduce NOx emissions by recycling a proportion of the combustion gases that normally exit through the exhaust. A valve is used to control the flow of gases, which are re-routed through the intake system, where they are re-combusted with fresh intake air and fuel. On a correctly functioning EGR system, this lowers undesirable exhaust emissions.
The problem with these systems, particularly with diesel vehicles, is that excess hydrocarbons are produced during the combustion process. These hydrocarbons deposit themselves on the EGR valve and periphery pipe work where the EGR routes back into the intake system. Over time, this clogs and eventually blocks the EGR valve and the associated pipework.
Additional Source of Deposit Build-up!
It is important to note that the carbon buildup you see in an EGR system and other emission control components is not only from the combustion process. In most cases, it’s a combination of combustion-produced hydrocarbons and also carbons and deposits from the crankcase oil. This is where many fail to correctly arrest deposit build-up on the EGR after it has been cleaned or replaced. More on this later…
What happens is engine oil can bypass the piston rings, valve stem seals and crankcase breather system (PCV). That oil is then consumed during the combustion process, but it isn’t fully combusted. The unburned oil and fuel are both recycled and deposited within the EGR. The oil in particular will polymerize onto the metal surfaces due to the very strong affinity between oil and metal. This newly formed surface then acts as a “sponge” for all further particulates in the recirculating exhaust gases.
Basically, what you have is a combination of bypassed oil and unburned fuel deposited within the EGR system. This turns into a solid, which builds up and clogs the EGR valve and associated pipework, causing faulty operation.
If the EGR valve begins to stick or is blocked up, the solenoid used to operate it will draw more current to open it. The ECU detects that condition and throws an engine warning light.
The symptoms of a faulty EGR include:
Excessive emissions/smoke during acceleration
Engine warning lights
As deposits begin to accumulate this restricts the flow of gases and disturbs the fuel mixture. The ECU is expecting a certain amount of recirculating gases as the EGR valve transitions from closed to open and visa-versa. These gases are not delivered as anticipated hence the disturbance in the air/fuel ratio. This can result in hesitation, stumbling and excess emissions, particularly during acceleration.
Natural Carbon Removal
Now, there is a natural cleaning mechanism for carbon and most additive manufacturers won’t tell you this. If you’re able to improve the quality of combustion, and are thus able to produce cleaner exhaust gases during the combustion process, these cleaner exhaust gases will naturally scavenge and remove carbon. This is also the case with many emission control components attached to the exhaust system, such as the hot side of the turbocharger, catalytic converter, or a diesel particulate filter.
You can naturally clean these areas. Many additives you see on the market today are essentially just fuel system cleaners and combustion catalysts. They might be promoted and marketed as EGR cleaners, DPF cleaners and so on, but they’re really nothing more than fuel system cleaners. What they do is restore the efficiency of the fuel system and by doing so, improve the efficiency of the combustion, which reduces hydrocarbon production. In addition, some products contain a fuel catalyst technology that in itself will lower the hydrocarbons produced. What you’re left with is cleaner exhaust gases, which will help naturally remove the carbon from these mentioned areas. Except for a very few products that contain patented technologies where molecules are activated during combustion (more on this later), such cleaners do not directly clean these areas, as the chemistry is destroyed during the combustion process.
The Problem with Natural Removal and EGR Valves
Now, this natural cleaning mechanism is not always effective when cleaning the EGR system. The reason for this is that when cleaning carbon from your engine, heat is the primary factor. It is important that there is sufficient heat. Heat, combined with the cleaner, recycled exhaust gases, helps remove carbon. The problem with the EGR is that the gases are usually cooled by the time they reach the valve and the periphery pipework. Therefore, the natural cleaning mechanism is not always as effective with EGRs, so you have to take alternative action.
Alternative Cleaning for EGR Valves and Systems
Unfortunately, the most effective way to clean an EGR is to remove it and clean it manually (if you have access to it). You’ll remove the EGR and the periphery pipework. Scrape off as much carbon as you can manually, then use a quality EGR aerosol cleaner such as Ecotec Soot Cleaner Aerosol, to clean the remainder and reassemble the system.
If you don’t have easy access to the EGR valve, you can use an in situ aerosol-based EGR cleaner that you can either spray into the EGR pipework or through the air intake and clean the EGR this way. However, particularly with diesel engines, you must be very careful. You don’t want to damage the engine. If you’re in doubt, you should let a trained professional carry out this procedure for you. For this we recommend the Ecotec Turbo Net and EGR Cleaner Aerosol.
Once the EGR is clean and operational it is important to take the steps necessary to prevent further carbon buildup. While you can never stop it completely, what you can do is maintain a manageable level of carbon that the engine can naturally consume without the deposits becoming excessive. If you were to remove the EGR, what you’d be looking for is a very fine layer of carbon that you can scratch off with your nail. Anything more than that would be considered excessive.
Maintain and Protect
1. Firstly, use a high quality polyetheramine-based fuel system cleaner and carbon remover to ensure injector and combustion efficiency is restored. Otherwise, you’ll end up with a clogged EGR valve soon after. For this we recommend Archoil AR6400 or AR6400-D MAX for diesel engines.
2. Secondly, you need a VERY high quality engine oil and/or oil additive that helps prevent oil bypassing the crankcase breather system or piston rings and polymerizing with the EGR system. You must tackle the problem from both the fuel system end and also the crankcase oil. For this I would recommend the Bardahl C60 fullerene range of engine oils as the advanced nano additive pack has proven to keep the EGR and similar systems clean. Alternatively use a high quality oil additive pack such as Archoil AR9100 or AR2300. These have shown to prevent polymerisation and even remove carbon from these areas in some cases.
3. Thirdly, and particularly if the majority of your driving is short or start/stop, use a high quality ongoing fuel additive containing an effective combustion modifier or fuel catalyst. For this we recommend Archoil AR6200 (petrol) or AR6900-D MAX (diesel). What this will do is improve the quality of the combustion and lower the amount of hydrocarbons being produced and thus recycled through the system, especially when the engine is in its warm-up cycle. Most of the time you’ll only use a little bit of the product at a time and a single bottle will last for multiple tanks of fuel.
Get Out and Drive
Finally, it’s important to make you aware our view is that most of today’s vehicles are commonly mis-sold. They are simply not designed for the short journeys that many people use them for – around town driving, shopping runs, school runs, etc. If the vehicle is not permitted to get up to temperature on a frequent basis, it’s inevitable that hydrocarbons will be produced and deposited throughout the system.
Because of the lack of heat, it will be very difficult for the engine and the emissions control components to naturally manage carbon within the system. Therefore, using the correct types of oil, fuel and fuel additives is essential to keeping the engine running efficiently.
If you require any expert advice or help then please don’t hesitate to contact us and either I or a member of my team will be pleased to help.
Products to clean the EGR – Intake Spray Carbon Cleaner (Intake, EGR, Turbo etc)
EcoTec EGR & Turbo Cleaner
For rapid fuel system cleaning
AR6400 (petrol) or AR6400-D (diesel)
Fuel conditioning, protection and carbon reduction
Nano oil additive pack to reduce circulating oil build-up in the EGR