It is called active regeneration. The compression ratio indicates how much the gas inside the engine cylinders gets compressed. Find Mercedes at the best price. Let’s say that the fuel injector can only fire 1000000000 times (I made this number up). CON: Although diesel fuel is considered more efficient because it converts heat into energy rather … In fact, the car is unlikely to even enter the regeneration cycle during urban stop-and-go driving. Countries outside of Europe, the United States, Australia, China and Japan follow a similar pattern of regulations with similar limits imposed. They may also slightly improve engine torque at low revs. Welcome to the space age. If you always drive a petrol car with the pedal to the metal, you are doing it right! The particulate matter needs to be burned off before the DPF becomes full. Time will tell how reliable the SCR systems are and how long they will last. Drivers should check their owners' manual to identify the appropriate light on the dashboard. Increasing the exhaust temperature is done by injecting extra fuel into the exhaust, where it burns. Keep in mind that this option is illegal because it increases emissions. Below is a list of things that often fail in diesel cars. Progress is vital, but there is a point where the next small bit of extra performance comes at the cost of a larger chunk of reliability. Free Member. This is why diesel cars are getting banned from entering city centres around the world. This isn’t a problem of diesel engines per se, but if you are considering switching from a petrol car or already have another petrol car in the household, it’s worth keeping in mind. Also, the engine needs to be in good working order. The DPF may be on its last leg after doing supermarket visits for the last 20,000 miles and running on some cheap engine oil that’s not suitable for diesel particulate filters. This leads to a more complete combustion, more power, better efficiency and less smoke. Too little fuel means that the engine is running lean. A traditional single-mass flywheel is a solid piece of metal that relies on its inertia to smooth out engine’s power delivery. In other words, diesel engines can do more miles before needing a rebuild or landing at the scrap yard. 4.70 Lakh - Rs. In other words, the engine delivers power in pulses, rather than constantly. Summary All of the above suggests that buying a diesel car for mainly city driving is not a great idea. Given: BMW F10, 3.0 diesel engine. If the car model you are looking to buy is fitted with “high risk” swirl flaps, you should take some precautions, like replacing the intake manifold with a new one. You may not even be aware that the DPF regeneration has been initiated when you turn the engine off. A 2500 bar fuel injector will throw a hissing fit very quickly when fed anything else than good quality, perfectly clean diesel fuel. For used vehicles, example monthly payments are based on : 48 month term, 15% deposit and 10,000 miles/year. Some of these components have relatively short lifespans, which is the source of the high maintenance cost of diesel engines. I find it funny that the DMF makes it possible to drive at such low revs comfortably, but it’s exactly what makes it wear out quicker. At high engine speeds and high loads, the swirl flaps open to increase the airflow. Active regeneration usually takes 5-15 minutes of continuous driving, ideally at a constant speed. The diesel particulate filter traps soot and burns it off when it gets full. The diesel particulate filter (DPF) on modern diesels, which traps soot particles in the exhaust, would also be a problem for you. scotia. The vehicle's computer determines when to regenerate the DPF based on the amount of soot/particulate matter in the filter. These filters need to be unclogged … Basically, if you drive your diesel car primarily on the motorways, you should have no problems with the diesel particulate filter. There are three types of DPF regeneration cycles: This type of regeneration happens when the exhaust temperature is high enough, i.e. A brand new manifold should be safe for quite a while. Its function is to feed the exhaust gases back into the engine to reduce emissions of nitrogen oxides. The typical diesel knock and emissions are reduced by spreading the injections into stages (pilot injections, main injections, post-injections). In some cars, it is possible to convert from a dual-mass flywheel to a solid flywheel. The result is a loss of boost pressure and reduced engine performance, eventually followed by the “Check Engine” light. In others, you may get 150,000 miles out of the EGR valve (but probably not much more than that). This should prolong the EGR valve life expectancy noticeably. In 2009 the "Euro 5" emissions standard was introduced by the European Union. The inner components of a DPF are expensive to manufacture as the soot/particulate they filter are so small. A dual-mass flywheel failure is definitely one of my favourite first-world problems. Carbon build-up is a side-effect of feeding exhaust gases back into the engine (EGR valve). As the name implies, their role is to inject diesel fuel into the engine cylinders at high pressures. Joking aside, if you buy a modern diesel car in poor condition or you’re simply unlucky, you may have to pay through the nose to keep the car going. Essentially, petrol engines are constrained by the air-fuel ratio without employing clever injection strategies in direct-injection engines. The state-of-the-art piezoelectric injectors can deliver up to nine injections in one cycle and dose fuel in milligrams. This is the worst-case scenario. At some point, it will be so clogged that it will put the car into “Limp Home” mode and illuminate the “Check Engine” light. Do you notice any similarities? Unfortunately, some engines are known for swallowing swirl flaps. As cars age, the cost of the replacement DPF could be more than the value of the car – and it is older, higher mileage cars that are most likely to require a new DPF. Short trips or start-stop driving does not allow the exhaust temperature to get high enough to initiate passive regeneration. Adding too much fuel means that the engine is running rich, which is inefficient because there isn’t enough air to completely burn all the fuel. fjs.parentNode.insertBefore(js, fjs); I’m sure you can already guess what happens to moving parts that are subjected to diesel exhaust fumes. The key part of the system is the EGR valve. The typical lifespan of a diesel particulate filter is somewhere between 150,000 and 200,000 miles when the car is used and maintained correctly. This includes the cost of a new clutch since it’s worth doing it at the same time to avoid paying for the same work in the future. The extra vibrations may damage the transmission in some cars because the gearbox may not have been designed to work with a solid flywheel to begin with. The ones that don’t have springs, rely solely on the DMF for damping. This is also the reason why manufacturers keep increasing the fuel injection pressures to ridiculous levels in order to make the fuel mix better with the air. The soot storage capacity is limited. Low mileage cars do rust. Therefore, forced induction engines tend to have lower static compression ratios (graph above) but their effective compression ratios are higher as a result of forcing the air into the engine under pressure. Today’s diesel cars may be powerful, quiet and very nice to drive, but the complexity has gone through the roof. Here’s what it looks like: The problem with the throttle plate is that it restricts airflow. It may get technical at times. At full throttle, the EGR valve closes and no exhaust fumes are returned to the engine. Also, many small droplets have a larger combined surface area than fewer large droplets (more efficient burn). Replacing the EGR valve costs somewhere between £300 and £600 at an independent repair shop. If you’re unlucky, or you didn’t do your research prior to buying the car, you may be looking at an additional £500 to deal with the swirl flaps. To add insult to injury, a problem with the EGR may cause issues with the diesel particulate filter. If the active regeneration cycle gets interrupted too many times or it never has a chance to even start, the DPF will continue to accumulate particulate matter. The other major improvement in diesel injector technology is the ability of piezoelectric and solenoid injectors to deliver multiple injections per combustion cycle. And here’s more on the topic of progress. The EGR in petrol cars is a good thing. Other Scottish cities expected to introduce Low Emission Zones. Also, some cars were already fitted with SCR systems, which were used as an alternative to NOx traps. If you look after your diesel car well, and 80% of your driving is on the motorway, there’s no reason why a DPF or other components should not last 200,000 miles. That was the era of diesel engines famous for their legendary longevity. It’s just that it is sensitive to poor maintenance and abuse. If the torsional vibrations are not dampened, they can manifest as transmission gear rattle at standstill or vibrations/noise when driving at low engine speeds (below 2000 RPM). 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