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nduction is the stage of the problem.There appears to be working cycle of an engine no single reason for a build-up in which the fuel and air is The next of contaminants in the intake drawnI into the cylinders. systems, and it seems some makes and models suffer more Contamination means to plague… than others. make impure by exposure to or addition of a polluting Source of substance. INDUCTION contamination Induction contamination means any change from the original state CONTAMINATION Carbon build-up around the of the complete intake system, fuel by Jeff Smit throttle body, throttle bore and inlet or air, of a vehicle. The air intake manifold restricts the airflow into the system includes the air filter box, air filter, engine cylinders. Such an obstruction air intake hoses, throttle body or butterfly will result in a poor idle, a stalling condition unit, inlet manifold, engine valves and even and a drop in performance and fuel the cylinder bores. economy. The most common source of these deposits is from the combustion and The incidence of vehicles losing power crankcase gases. and performance because of some form of Take the inlet manifold, for example. Once, induction restriction is increasing greatly. there was a carburetor sitting on top of The combination of the gases from the TaT sees evidence of this problem through the engine. Fuel was delivered above the positive crankcase ventilation (PCV) the increasing numbers of TaT assist throttle plates, which were awash in petrol, system and from the exhaust gas requests. Some of the pictures showing one of the world’s great solvents. recirculation (EGR) system will, in most serious build-up of carbon have come cases, cause the intake contamination, So carbon could not build up because of from TaT workshops and others from our more so when the PCV and the EGR the washing action of swirling, fuel laden subscribers. points are positioned near the throttle air. plate. The EGR gases mix with the gases It raises the It’s fairly common now to find vehicles with from the PCV system to form the gummy question – what’s very dirty inlet manifolds and throttle bodies or waxy residue. bad enough to cause some components to The piston strokes and the negative to changed? stick and fail. Customers complain of a loss positive pressure pulsations direct the of power or poor fuel economy. And what do the aftermarket workshops gases towards the throttle body, where need to know? Is there a need for some Vehicles began suffering from induction they are baked on due to the intense heat. education of the motoring public? Can the contamination with the introduction of the Foreign and domestic vehicles suffer contamination trend be slowed or reversed first electronic fuel injection (EFI) systems. equally. through some preventative measures? While these systems bring many benefits, Many things are blamed for the build-up of including improved performance, fuel Engine PCV system carbon in inlet manifolds – poor fuel quality, economy and lower emission output, they are subject to intake and throttle bore The vapours that end up in an engine’s poor or incorrect engine oil, engine design crankcase contain moisture as well as and even driving styles. contamination problems. Once fuel was stopped from passing through the throttle combustion by-products and unburned Sometimes technology generates new bore, contaminants began to build up. fuel vapours. The crankcase is sealed to problems. Is the build-up of carbon in the prevent the escape of these gases into intake system one of Eventually, those carbon deposits must be the atmosphere, but the vapours must them? removed to restore engine performance. be removed to prevent oil contamination Strict environmental controls, Euro 4 that leads to sludge formation. The PCV emissions standards, and consumer system siphons these vapours from the demands for better fuel economy crankcase and routes them into the intake and performance forced design manifold so they can be reburned in the engineers to develop direct engine. injection systems for both petrol The main component in the PCV system is and diesel engines. These the PCV valve, which is usually located in systems took the introduction the valve cover. A hose connects the PCV of the fuel away from the inlet valve to the intake manifold. manifold altogether.So yet again the introduction of new and The PCV valve is spring-loaded with a supposedly better systems has specific orifice size designed to restrict the by their very design caused a spin-off amount of air siphoned from the crankcase into the intake manifold. This is necessary because air drawn There are a number of through the valve from the crankcase has a EGR system types: leaning effect on the fuel mixture, much the • Ported same as a vacuum leak. (late 1960s to present) So airflow through the valve must be • Positive backpressure controlled within certain limits. At idle, air (1970s to present) flow is reduced because little blow-by is • Negative backpressure produced. (1970s to present) When the engine is cruising and vacuum • Pulse-width modulated is high, airflow through the PCV valve is at (early 1980s to present) a maximum to purge the vapours from the • Digital–electronic crankcase. (late 1980 to early 1990s) EGR system • Linear–electronic (early 1990s to present) A chemistry lesson on NOx first. It’s the later model types The ‘x’ in NOx stands for the various that are linked with the direct change, the oxides of nitrogen that are created. injection systems which concern build-up continues. technicians today. Eventually, the Among them are: NO (nitric oxide), a build-up causes more colorless, poisonous gas; NO2 (nitrogen issues with poor performance dioxide) which is a reddish brown, toxic Symptoms of EGR and fuel economy which in turn cause gas; and N2O (nitrous oxide) which is more PCV gases. Eventually the EGR commonly known as laughing gas. malfunction valve won’t seat correctly and allows EGR Environmental imperatives will demand gases to enter the throttle body at idle and The EGR system is often misdiagnosed compound the problem. continuing control of nitrogen oxide or blamed for problems that may not be emissions. Most of the carbon monoxide its fault, including hard starting, stalling Some of the worst cases we have seen and almost 50 per cent of the nitrogen and hesitation during warm-up, rough have been on common rail diesel vehicles. oxides and hydrocarbons come from idle, missing, spark knock, backfiring and A lot has been said about the quality of burning petrol and diesel fuels in cars and loss of power. Sure, the EGR system can diesel fuel, and perhaps this is a small trucks. cause these symptoms, but so can other contributor to the problem. There have Nitrogen oxides are only created at very components and systems. Don’t jump to been issues with vehicles losing power high temperatures and pressures, as found any conclusions until you have checked and becoming barely driveable. The top in automotive engines. the basics. One common reason is carbon part of the inlet manifold is found to be build-up in the intake system. choked with carbon. In some cases the Basic EGR operation inlet manifolds have had to be replaced It appears that with the introduction because of the extent of the contamination of the Euro 4 emission standards, the NOx forms under high pressures and and damage to the manifolds. EGR system may be operating in many temperatures found in the combustion more situations than in previous models, There have been stories that some chamber, so it can be controlled by sometimes at idle. technicians have even blocked off the EGR reducing the compression or the system and fitted oil traps in the PCV lines. temperature in the combustion chamber. The build-up of contamination in the intake TaT has heard that manufacturers are system can be caused by a number of Emission control engineers chose the working on software upgrades to try and possible factors. First, the engine needs to latter. Temperature is controlled by minimise the problem, but this may not be be in good working order so that the PCV introducing a metered amount of inert gas enough. gases are as low as possible and as clean into the cylinder to partially quench the fire. as possible. This is where correct and There are many good products available The result is that the fire in the combustion regular servicing, as well as quality and which can help clean and maintain the inlet chamber is less intense. EGR exhaust correct engine and drive train oils, are very manifold. important. gas occupies space that would otherwise The BG product for both petrol and diesel contain air. It is TaT’s belief that many technicians engines is one that we know works very With EGR, the fire is more like a would claim that the servicing schedule for well, and there are no doubt others. the modern vehicle is too stretched out. smoldering pile of leaves than a blast It’s a problem which will need some furnace. Car makers have been promoting low customer education so that the clearning Exhaust gas was chosen because it is free cost service, but this has had the effect and servicing of the throttle body and inlet and plentiful. of teaching vehicle owners that they manifold are included as an important can get away with one service a year or part of every service. You owe it to your EGR reduces the formation of NOx up even worse, every 18 months. This puts customers to let them know about this to 60 per cent. The cat usually cleans up the engine under high stress, causing issue so that you can at least ensure much of the rest. excessive build-up of PCV gases. continued top performance of later model The EGR valve would normally open vehicles. Then we add the EGR to the equation. during light throttle and warm engine The EGR valve is now operating more TaT invites technicians to share their cruising and channel the exhaust gases frequently and even at idle, this high heat knowledge of this problem because the back into the engine’s inlet air. It doesn’t coupled with the excessive PCV gases industry is only now seeing the early take much. entering the intake system triggers the stages of contamination. Please send EGR accounts for less than 10 per cent of process of carbon build-up. your photos and your remedies. TaT will the total air/fuel mixture but even this small continue to cover this important subject. At first it doesn’t cause too many problems. amount of non-flammable stuff is enough In the meantime, the TaT field specialists But as time goes on, with stretched to quench the flame somewhat. were invited to share their experiences. out servicing and a quick oil and filter Anthony Tydd: Jason Smith: There are rumours that manufacturers might have to rethink their EGR strategy, From what I have seen it’s the turbo diesels Petrol engines so stay tuned for this. But I don’t know how that have the biggest problem, probably they will get around this to comply with due to the engine trying to recirculate soot I have been cleaning throttle bodies for strict emission specs. back into the inlet. more than 20 years expecially in the early days when no one else would do it. Maurice Donovan: The Mercedes Vitos and the VW soot up If the car had a rough or low idle, many big time in the inlet. I have seen them so Many people blame the EGR for the mechanics would wrongly adjust the bad I have tried to scrape the carbon out carbon build-up. This is justifiable because throttle plate stop screw to bring the idle so the engine could breathe. the EGR is recycling exhaust gas back into up. This then created a problem. After the induction system. There is a general I am surprised manufacturers have not cleaning the very dirty throttle body, the opinion that unburnt fuel gas is the biggest played more with water injection at the car would idle far too fast. A base idle reset cause of the build-up inside the intake throttle body to cool the charge and clean had to be done to make the car right again. system. the inlet shiny new. I have always used a toothbrush and the I still believe if a fuel is poor quality or if Ask any mechanic who has done a Ford appropriate cleaning solution and found the mixture is over rich caused by leaking head gasket and you will find that the this did the job quite well. A large workshop injectors, more of this unburnt fuel will be cylinder that has been getting water into it I once worked in reported a saving in left in the intake system and cause sludge. will have a shiny piston top and polished the amount of throttle body cleaner they like an exhaust valve. were using after adopting my toothbrush However, I am starting to think that techique for all the mechanics. crankcase oil caught up in the breather and The diesel engine may not be as entering the intake system may be a bigger accommodating to my idea as the petrol Cleaning throttle bodies has now become issue then we realise. Some years back I engine. a crucial part of servicing late model was involved with the import and servicing vehicles. of the Toyota Surfs 2 litre and 1KZ engines. A lot of turbo engines seem to seep oil past They had a major problem with oil the turbo bush and back into the inlet tract A 120 series 2006 Prado which had entering the intake system. which is another compounding problem for always been dealer serviced inlet contamination. was brought to me for At the time I put it down a major service. The to bad design in the I believe the biggest cause of carbon throttle body was engine breathing build-up would be the use of low grade oils extremely dirty. system. I had or too long an interval between services. Having said that, modified the Either of these would cause carbon build- I admit it is not breather, fitting up and feedback into the inlet via EGRs an easy throttle steel wool inside, and rocker cover breather (the baffles body to check and when that inside to separate oil from blow-by gas). and clean. did not work I I have seen rocker cover breathers block After cleaning redesigned the up due to lack of oil changes. The vent the throttle bodies inside of the rocker galleries close up and become venturi-like, on these cars, the cover with bigger increasing the air speed and dragging oil engine idles all over chambers and more into the inlet. the place. A tip – either baffles and even this did perform a relearn with the not work. I also had turbos In one such case, a dealership quoted on scan tool or take the car for a long rebuilt to ensure that they were a new engine because of oil usage. The road test. Even after this, the car will still not the culprit. customer wanted a second opinion and we need a day or two for the idle to settle No matter what I tried I could not solve this cleaned out the rocker covers and it was all down. problem. The Toyota Estima with the lay- fixed with no more oil usage. Dedicated throttle body and intake cleaning on-the-side 3CT engine is even worse. The early Daihatsus had a breather and decarbon machines are available now. I have this unproven theory that when the hose from the rocker cover to the intake These can clean the throttle body, butterfly turbo is on boost it would pressurise the manifold. It had a restrictor in it. When face and behind the butterfly face. They engine through the breather. When the it got blocked, a new vacuum hose was can also do the inlet runners, the backs turbo comes off boost, the pressure being usually fitted, ignoring the restrictor and of of the valves and some claim the oxygen released from the turbo creates a vacuum course it started sucking oil while driving. sensor as well. and draws the oil up into the intake system. Most of the Saab diesels would have I am getting excellent results from one I have in the past blocked off EGR systems logged a fault code before 110,000 of these machines, especially with BAs, in Surfs due to running factors, but this kilometres due to the EGR being blocked. BFs and Territories which are a little off at has not stopped the build-up forming in the idle. Perform the upper engine clean and They are easy to unblock and free up if intake system. The issue of poor quality decarbon, replace the plugs and they purr seized and my take on it is that the diesels fuel being the cause is another argument like kittens. It’s also another way to make are made for long driving, not for putting and possibly has some truth, but I have a dollar. around town like Miss Daisy. witnessed badly sludged build-up in the More tips – It is a good idea to replace diesel intake systems on used engines that Turbos hate this too. People who have no the spark plugs after performing the upper are straight out of Japan. I have been told intention of using the turbo, shouldn’t buy engine clean and decarbon and not before. that Japan has a better quality of fuel than one. Sometimes, when performing the clean, a ours. People buy diesels because they can get fault code can be logged in the ECU, so it With the advent of common rail direct seven litres per 100 kilometres but they will need to be cleared. injection, it would seem that the intake putt around their suburbs and rarely give build-up has escalated to plague the engine a chance to breathe. Diesel engines proportions. This is why a lot of them have blocked Complaints about late models with very I admit I have been blaming the poor fuel particulate filters as well. dirty inlet manifolds are increasing. and the EGR, but after my experience with a Hilux I am starting to think back to I realise petrol engines also have problems It’s not hard to understand that the engine all my past experiences and I continue to and I am comfortable with the fact that our can then breathe properly again. question the main cause of this sludge. I do fuel quality has a lot to do with this as well TaT and its specialist workshops are not know why common rail systems appear as other factors. highlighting this growing problem in the to have a much bigger issue and this is Generally speaking, petrol engines, if hope that some answers might emerge, another issue I would like to investigate. serviced regularly and with the right fuel either from fellow workshop technicians or Many people blame everything to do with treatments and the necessary induction from engine specialists. diesel sludge as a fuel issue and I know servicing, will keep most petrol engine this is not always the case. It’s a problem intake systems under control. In the meantime, working on the principle we all need to understand. that shared knowledge is worthwhile, TaT I have been using the BG products for both invites technicians to send in their photos It is not enough to have the best product on the petrol and diesel engines for some time and ideas about contamination build-up in the market to clean this sludge out of the and have found them to be very good. engines. induction system. Most customers comment on how well their Only by sharing examples and techniques The fact is, there should never be this vehicles are running after the induction will we ever find the truth. much sludge in the first place. system has been cleaned.

Essential Service Programs (ESP), the Australian The cleaner should be used only with BG specified distributors for BG Products USA, have added tools and adaptors. BG already has a two-part a new diesel induction service video to the BG petrol intake and fuel system service to help section of their website to show the procedure technicians cope with the growing issue of and effect of the new BG diesel induction system intake and induction contamination on a cleaner. The BG diesel induction system cleaner range of vehicles. will liquify and remove the most stubborn oil The new video can be viewed at: deposits and unburned fuel formed by EGR and www.espro.com.au PCV gases as they pass through the air intake and intake valves.They are then burned in the normal ESP 02 9911 4040 combustion process. [email protected]

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