Exhaust gas re-circulation (EGR) and the BG Air Induction Service

I want to take a quick moment to talk about one particular achilles heal and possible cause of driveability issues in the modern diesel engine, Exhaust gas re-circulation (EGR), specifically in diesel vehicles (although it does effect petrol engines, although to a lesser extent).

With the advent of clean diesels, one of the larger changes has been the massive increase of EGR levels running through the engine. EGR takes some exhaust gas, runs it back through your intake manifold via a metering valve (the EGR valve) at different quantities varying on throttle position and load on the engine. Why would we want this dirty exhaust gas going back through the engine, that seems silly.

The exhaust gas is mixed with fresh intake air to lower the temperature in the combustion chamber. Even though the exhaust gas is hotter than fresh air, it contains hardly any oxygen, as that has already been burnt and cannot be burned again. So less oxygen means less explosion, which means less heat and pressure. But why? Over certain heat and pressure levels in the combustion chamber comes the massive increase of Nitrogen Oxides (NOx) gases. These nasty gasses are high on the EPA (Environmental Protection Agency) hitlist. They are a massive problem with internal combustion engines and will in the future contribute to the breathing problems of many humans. They are responsible for many environmental misfortunes such as smog and acid rain.

Unfortunately, these hot exhaust gases mix with ‘blow-by’ oil, created from pressurised gas passing past the piston and also being routed back through the intake to avoid pressurising the engine’s crankcase. This creates a hard tar like carbon substance to build on the walls of your intake manifold, valves and associated components, eventually starving your engine for air, causing poor fuel economy and all matter of driveablilty issues – usually first indicated by black smoke on acceleration or surging.  A quick google image search of diesel intake carbon will quickly open your eyes to the horrors of intake carbon, much like seen below.

What can we do about it?

Whilst there are measures to reduce the contamination, which I will not touch on in this article, once it is there it needs to be cleaned out, be it manually or by chemical means. Manually involves removing the intake manifold and physically cleaning it, which can be a smaller 3 hour job, right up to some engines that require engine removal to remove the intake manifold. 

At Steve Sorensen Mechanical we are proud to be one of the only workshops in Australia, working in partnership with the American company ‘BG Products’, to offer the BG Diesel Induction service. Many videos can be found on youtube, from all over the world showing the benefits of this system, we find this one to be particularly enlightening:

During this multistage process, with the main component being the strategised injection of a patented chemical via an electronic timer box, into your intake manifold, it can effectively break down carbon deposits, delivering you back the power and fuel economy you came to know and love your common rail diesel to have before it’s inevitable blockage. We recommend using this system anywhere in the range from every 50,000km to 100,000km depending on the conditions your vehicle is driven in, to ensure the intake system provides the necessary fresh air for your diesel engine to perform effectively. The pictures below show a relatively mild case of a an EGR valve starting to carbon up, the danger here is this valve will eventually become sticky or seize open, at which point your EGR flow will multiply and carbon buildup will start to multiply quickly. The chemical, after passing through the intake over the course of the 1-2 hours that the service takes, cleans the carbon from every nook and hard to reach passageway of your intake.


Our research has shown amazing before and after results in a scientific manner, using the cars standard mass air flow sensor, we can calculate volumetric efficiency (the ability of air to flow through your engine), showing very sizeable increases after performing this service.

 Please note this induction service is best done at the same time as a scheduled engine oil and filter change, as the oil must be replaced directly after to avoid any issues with oil dilution after the induction service is performed.

Call us today to talk about how we can maintain and restore your diesel fuel efficiency and driveability.