Diesel engines have higher compression ratios as compared to petrol engines because it is necessary to initiate combustion. It’s time to get to the point of this article. Find Mercedes at the best price. As is often the case, this comes at a price because engineering design at this level of technological maturity is almost always a compromise. It’s not uncommon for a DPF to cost €1500 for the part alone excluding the labour for fitment.. © RTÉ 2021. If you are doubtful, get expert advice. However, if you drive a car with a DPF mostly in the city, well, you bought the wrong car. You also have the option to opt-out of these cookies. The DPF itself is fairly reliable. Eight- and nine-speed automatic transmissions are becoming quite common in SUVs, cars, and trucks. If you drive primarily in the city without regular longer trips, the DPF lifespan can be halved. Also, turning the engine off during a regeneration cycle is a bad thing. Its job is to smooth out the jerky nature of the engine’s power delivery. This website uses cookies to improve your experience while you navigate through the website. The DPF filters pollutants through small fibres within the housing. Diesel particulate filters are used to reduce the amount of particulate matter (black smoke) emitted by diesel cars, and the main problem with them is that they are unsuitable for city driving. If you always drive a petrol car with the pedal to the metal, you are doing it right! Especially on an older, low-mileage model, infrequent vehicle use or frequent use for short trips can cause rapidly accelerated corrosion within the exhaust system. My back-of-a-cigarette-packet calculations tell me that you should be doing at least 12,000 miles every year for the fuel savings to offset the potential cost of maintenance. This leads to a more complete combustion, more power, better efficiency and less smoke. Pretty much all modern diesel cars are turbocharged, so don’t let a low compression ratio (16:1) deceive you – their effective compression ratio can be pretty high. Diesel fuel is injected into the engine cylinders, and it is ignited by the high temperature generated through compression. Burning off the particulate matter creates extra CO2 and some ash. Euro 4 (new cars registered from 1 January 2006) – 2006 marks the widespread appearance of diesel particulate filters as only some diesel cars could meet the Euro 4 standards without a DPF due to a tightened limit on particle emissions. Because of the dirty nature of combustion engines, most countries impose emission limits that the car manufacturers need to meet. The soot remains trapped in the filter while the exhaust gases get released into the atmosphere. When progress compromises reliability, I think it’s time to stop. This has led to some motoring experts warning low mileage or mainly urban drivers that they should not to be tempted away from petrol cars by better diesel fuel economy figures. These cookies do not store any personal information. It’s cheaper and some people choose to do so to avoid recurring problems (popular decision among fleet owners). The injection pressure in the old-school diesel engines with indirect injection was lower than 150 bar (150 times the atmospheric pressure). Improvements in fuel injection technology are what made modern diesel cars less diesely (for a lack of a better word). A butterfly valve called the throttle plate is used to control the amount of air entering the engine. Replacing the EGR valve costs somewhere between £300 and £600 at an independent repair shop. The ones that don’t have springs, rely solely on the DMF for damping. Here’s how to control a diesel engine: That’s pretty much it. However, success comes at a price in this case. Dual-mass flywheel replacement typically costs between £700 and £1200. You would be surprised how much sludge and carbon gets deposited in the air intake manifold due to EGR action. In some cars, the EGR valves are a recurring problem due to poor design and may need replacing every 50,000 miles. For the sake of example, let’s say that you bought one with 150,000 miles on the clock, and you are planning to keep it for three or four years. It’s a low mileage car, though. The catalytic converter turns the hydrocarbons and CO into CO2 and water. 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. Urban driving is usually the problem. The extent of damage depends on plain luck and whether the swirl flap is made of metal or plastic. Required fields are marked *. 4.70 Lakh - Rs. At full throttle, the EGR valve closes and no exhaust fumes are returned to the engine. The first-generation directly injected diesel engines were quite good too, albeit a lot more complex and more expensive to maintain. If you rarely leave the city for a longer trip, you are likely to dramatically reduce the lifespan of the DPF in your diesel car. 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. This low mileage sought after diesel crew cab 4X4 pickup has just 2,466 kms. All modern petrol and diesel cars are fitted with an Exhaust Gas Recirculation (EGR) system. The total pollution is higher. Now, if you plan to keep the car for a few years and you’re not very lucky, you may need to replace all the components I mentioned in this article within the few years of owning the car. When the DPF is full it goes through a cleaning phase known as "Regeneration". You may find some information about dodgy swirl flaps in particular car models. Even when the engine is capable of running lean, the emissions of nitrogen oxides (NOx) can go through the roof. Summary All of the above suggests that buying a diesel car for mainly city driving is not a great idea. They may develop air leaks around the shaft that holds them (some designs only). 2032. Therefore, car manufacturers implemented a solution to force the exhaust temperature to rise to around 600ºC and clear out the DPF. High mileage diesel cars are nearly as expensive to maintain as the Space Shuttle. It’s just that it is sensitive to poor maintenance and abuse. Essentially, the EGR and swirl flaps are two systems that don’t work well together. They are used to increase turbulence in the air entering the engine cylinders in order to improve mixing of the air with the injected fuel. The amount of CO2 emitted by a combustion engine is linked to its efficiency. Diesel cars are being demonised, but are they really as bad as they're being made to seem? Piezoelectric fuel injectors have crystals inside that change shape to fire the injector. Feeding a solvent into the combustion chamber works against the oil film that prevents pistons and cylinders from wearing. Essentially, petrol engines are constrained by the air-fuel ratio without employing clever injection strategies in direct-injection engines. Another model from the Volkswagen Auto Group shows up here in the form of the Audi A3, and it bears the same 2.0-liter,… They close at idle and low engine speeds to create a swirl in the air going into the cylinders. There is also the option of injector reconditioning for about half the price of a new set. You get condensation in the box sections. Buying a diesel car with a DPF for urban driving is a false economy. This can be tricky to detect visually, as moisture will build up inside of the exhaust system, rusting it from the inside out. Typical carbon build-up on the swirl flaps, Dual-mass flywheels dampen torsional vibrations entering the gearbox (green line), The springs in the centre of the clutch plate dampen shocks and torsional vibrations. The state-of-the-art piezoelectric injectors can deliver up to nine injections in one cycle and dose fuel in milligrams. 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. Historic MG marque pitched as affordable electric car brand, Driving in bad weather - what you need to know. Swirl flaps are mechanical parts. With diesel cars getting banned from entering city centres all over the world because of their emissions, I feel that diesel engines don’t make much sense in passenger vehicles unless you drive a lot – enough for the fuel savings to offset the high maintenance cost and then some. If you take all of this into account, a modern diesel engine is about 20-25% more fuel efficient as compared to a direct injection petrol engine and closer to 30% more efficient when compared to a port-injected petrol engine. It’s a shame that smog isn’t healthy. So basically a good clean family car. If the DPF warning light does not go out or is accompanied by an Engine Management Light, bring the vehicle to your nearest main dealer immediately. Looking for more cars? Apart from soot, diesel engines emit high levels of nitrogen oxides (NOx) due to the lean-burning nature of diesel combustion. Here's everything you need to know if you own a diesel or are thinking of buying one A traditional single-mass flywheel is a solid piece of metal that relies on its inertia to smooth out engine’s power delivery. The mechanism that adjusts the swirl flaps may fail. It is called active regeneration. There are three types of DPF regeneration cycles: This type of regeneration happens when the exhaust temperature is high enough, i.e. The higher the injection pressure, the higher the abrasive action of fuel being forced through 0.1 mm holes (orifices). However, problems often start when the car approaches the 150,000 miles mark. These emission standards became so stringent that getting diesel engines to pass has become very difficult and requires many engineering workarounds. For regeneration to occur the vehicle needs to reach a combination of predetermined engine rpm, engine temperature and vehicle speed and this would ordinarily require a 40 to 60-minute motorway journey. Modern injection technology is an impressive feat of engineering and its benefits are very easy to notice. js.src = 'https://stillrunningstrong.com/wp-content/cache/busting/facebook-tracking/fbsdk-en_GB.js#xfbml=1&version=v3.2'; Welcome to the space age. The vehicle's computer determines when to regenerate the DPF based on the amount of soot/particulate matter in the filter. At high engine speeds and high loads, the swirl flaps open to increase the airflow. It still does not include any swirl flap maintenance. Also, a tightened NOx emissions limit meant that some cars had to be fitted with NOx traps, which proved to be not as effective as expected (VW emissions scandal). I’m sure you can already guess what happens to moving parts that are subjected to diesel exhaust fumes. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Nevertheless, diesel fuel injectors are precision devices, and they are not nearly as simple as they used to be. 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. Its disadvantage is the need for additive refills every 80,000 miles or so, and the system is even more complex. hello stw.. please share your knowledge with me as i have many differing opinions from my colleauges.. This variant of the DPF is used by the French PSA Group (car brands: Peugeot, Citroën and Vauxhall/Opel since 2017). In other words, diesel engines can do more miles before needing a rebuild or landing at the scrap yard. An EGR valve that doesn’t fully close will reduce power and increase fuel consumption. Some of the components in these systems are not very reliable. The other major improvement in diesel injector technology is the ability of piezoelectric and solenoid injectors to deliver multiple injections per combustion cycle. You may need a new set somewhere between 150,000 and 200,000 miles. 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. Although, I reckon that you could finish the OEM dual-mass flywheel off in 50,000 miles in some cars with 100% urban driving at low engine revs. Cars with diesel particulate filters require low ash engine oil and regular regeneration cycles. Low-mileage, young used cars are usually a bad deal because they haven’t depreciated enough. Swirl flaps are installed in one of the two intake ports per cylinder. Let’s say that the fuel injector can only fire 1000000000 times (I made this number up). In other words, find a 10-year-old car with only 10,000 miles on the odometer, and you’re probably looking at a great buy rather than a wide range of potential problems down the line. The EGR system recirculates exhaust fumes during idle, low loads and low RPM. 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). A common problem in diesel engines is the EGR valve getting stuck because of carbon deposits. The engine computer will raise exhaust temperature by altering engine timing and fuel injection quantity. For diesel engines to conform to the Euro 6 emission standards that came into force in 2015, all diesel cars need to be fitted with Diesel Particulate Filters (DPF) and many cars will require Selective Catalytic Reduction (SCR) systems that spray ammonia or urea into an SCR catalytic converter mounted to the exhaust system. I'd like to buy a diesel BMW X3 2.0 but most of my journeys are short. Solid flywheels are inexpensive and don’t really wear out when not abused. From that moment on, car manufacturers have been increasing injection pressures and reducing the diameters of the orifices in the fuel injector tips. If there is reasonable access to the EGR valve in your car, I recommend taking it out and cleaning out the soot every 50,000 miles. That can't be done these days, however. That means the opposite is also true. I recommend doing some research before buying a modern diesel car because there are cars out there with some really poor swirl flap designs. On a positive note, diesel engines are pretty good when it comes to carbon dioxide (CO2) emissions. Removing the DPF permanently is possible (it’s called a DPF delete). Active regeneration is typically required every 300-700 miles in typical driving (urban + motorway). Your email address will not be published. Meáin Náisiúnta Seirbhíse Poiblí na hÉireann. 24 kmpl. Also, the engine needs to be in good working order. Also, the engine needs to be in good working order. You control the amount of fuel added by the fuel injectors and make sure there is enough air to burn it all. It’s a different story in diesel cars. 2.46 Crore. - For more news, reviews and Top Tens, visit https://www.honestjohn.co.uk Look for higher mileage, well-made used cars with excellent longevity ratings. The original diesel particulate filter is there too, but if you’re not interested in cars, you probably didn’t even know about it (you will after reading this article!). See 29,076 results for Diesel cars with low mileage for sale at the best prices, with the cheapest car starting from £123. In a way, actively regenerating the DPF is like bombing for peace (or f***ing for virginity). Modern diesel cars are great when they are new. Swirl flaps live in the air intake manifold. Additionally, the injector cost is exponentially higher. As for diesel engines, emission limits started becoming problematic for drivers and manufacturers with the introduction of Euro 4. This is the worst-case scenario. It's diamond black crystal pearl in colour . Diesel fuel, also called diesel oil, is a better lubricant than petrol, while petrol is a better solvent. Car reliability survey for the sample to be split between petrol and diesel cars, and it's the unleaded models that have taken seventh spot in the most reliable list. Drivers should check their owners' manual to identify the appropriate light on the dashboard. Because of this, the internal parts of a diesel engine tend to last longer. }(document, 'script', 'facebook-jssdk')); This article will help you decide if a modern diesel car is a right choice for you. We have 163 cars for sale listed as: ford focus diesel low mileage, from £1,395 The flaps are operated by an actuator (vacuum actuator or electric motor). 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. Here is a list of 16 best mileage cars available in India in the price range of Rs. Cars fitted with diesel particulate filters burn more fuel than cars without. It's also one of the easiest things to … Passive regeneration is a slow oxidation process and it may not be enough to fully clear the soot, and not all cars are capable of passively regenerating anyway. Please note that I’m referring to the engine internals. The RAC says that performance modifications can damage a DPF, as can the use of low-quality fuel. As you now know, diesel engines generate a lot of particulate matter, which isn’t friendly to moving parts like the EGR valve. Please note that solid flywheels also dampen torsional vibrations. Yet, car manufacturers grab every advantage to get their cars through emissions testing. Most diesel car owners are wasting money - because they don't do enough miles to get the benefit from their engine, according to … Too much air won’t hurt (to a certain point at which the engine blows up). They are at their most efficient on long journeys and have particular problems when being driven on short journeys at low speeds. They are the source of particulate matter (soot) that diesel engines are infamous for. Low mileage diesel drivers may be wasting their money. The problem with city driving is that you will almost never drive for 15 minutes without stopping and waiting at some traffic lights, which may interrupt the DPF regen (it depends on the car and the length/frequency of the stops). (function(d, s, id) { If you take the car to the dealership, you can add 50% or double those figures. Whether you continue driving short distances with an orange light is a judgement call. 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. That’s why some modern diesel cars are not much louder than petrol cars. While emissions from petrol engines can be dramatically reduced by catalytic converters, diesel engines require a lot more exhaust after-treatment. Countries outside of Europe, the United States, Australia, China and Japan follow a similar pattern of regulations with similar limits imposed. The car still has the original dual-mass flywheel, injectors and even the EGR valve managed to survive this long. However, not knowing the car’s history increases the risk substantially. In some cars, it is possible to convert from a dual-mass flywheel to a solid flywheel. High RPM torque and power output are not affected unless the swirl flaps don’t work properly or carbon build-up becomes severe. RTÉ is not responsible for the content of external internet sites. You don’t get the benefit of reducing throttling losses, and the EGR valve leads a much more difficult and shorter life. The price above is what independent car repair shop will charge you. If you drive well below the average mileage each year, then although the car may be above average at purchase, it could be considered below average at sale. Dual-mass flywheels make cars smoother and quieter. Exhaust gases get recirculated back to the engine. Carbon build-up is a side-effect of feeding exhaust gases back into the engine (EGR valve). However, when they are designed well, they aren’t as problematic. Here’s what it looks like: The problem with the throttle plate is that it restricts airflow. Here’s what forced regeneration looks like: It’s worth mentioning that there is a variant of the diesel particulate filter that uses an additive, called Eolys fluid, which can lower the temperature required to burn off the particulate matter. All that was required to get them to run was a mechanical injection pump, spring-loaded fuel injectors and some optional electronic bits. If this sounds great, wait until you get the bill for replacing the DMF in your car. The whole point of swirl flaps is to reduce emissions. Here’s a quick summary of what you should take away from all this: Modern diesel exhaust system is a sophisticated chemical reactor. Active regeneration usually takes 5-15 minutes of continuous driving, ideally at a constant speed. In other words, this alone should give you 12% improved fuel economy in diesel cars because you can burn less fuel to perform the same amount of work. Comment document.getElementById("comment").setAttribute( "id", "ae734a73ba4cb966e237459e1134642a" );document.getElementById("hbef678ffc").setAttribute( "id", "comment" ); Necessary cookies are absolutely essential for the website to function properly. Modern diesel engines still operate on the same principle as 40 years ago. On the other hand, some cars run perfectly fine with solid flywheels with a minimal difference in the level of noise and vibrations. An alternative option is to remove the swirl flaps altogether. Dual-mass flywheels fail much quicker in diesel cars as compared to petrol cars because they get pummeled by the higher level of torsional vibrations. However, keep in mind that not all modern piezoelectric injectors can be reconditioned. When the car detects that the diesel particle filter is becoming clogged (around 50% full) it will try to initiate an active regeneration cycle. That can happen only when the car is driven for half an hour or so at 50mph or more. Even running the car low on diesel can cause … Too little fuel means that the engine is running lean. This website uses cookies to improve your experience. A swirl flap may become detached and get ingested by the engine. - madf : Having bought one Pegeot 106 11 years old with 28k miles for younger son and SWMBO having a 44k miles 106 diesel which is 15 years old (owned from new), I have some expertise in this field.. 1. Unfortunately, I can’t say the same about the diesel injection system or the auxiliary parts that reduce emissions. If the DPF is removed, the car’s ECU needs to be reprogrammed to stop dumping fuel into the exhaust system. This is why diesel cars are getting banned from entering city centres around the world. Driving at low engine speeds (1000-1500 RPM) shortens the lifespan of the dual-mass flywheel. The black smoke that you sometimes see behind diesel cars is the particulate matter (soot). Ford Aspire Variants. Imagine trying to breathe through a straw. Restricted driving ranges can create expensive problems for owners of diesel cars, if they're not careful. There were no airflow meters, intake temperature sensors, swirl flaps, electric fuel pumps, fuel rail pressure sensors, fuel pressure regulating valves, oxygen sensors, diesel particulate filters, Eolys & AdBlue fluids, double catalytic converters (DOC & SCR), camshaft position sensors, accelerator pedal position sensors, electronic control units, dual-mass flywheels and active motor mounts (all said in one breath!). 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. fjs.parentNode.insertBefore(js, fjs); The injection technology used today is called Common Rail from the “common” high-pressure fuel rail that feeds the injectors. The main problem with dual-mass flywheels is that the improvement in comfort and noise is often so small that it doesn’t justify the cost of the DMF and the reduction in reliability as compared to using a single-mass (solid) flywheel. I feel that modern diesel cars have gone past this point. The soot storage capacity is limited. Nevertheless, particulate filters are actually quite effective, and cars with DPFs emit even 90% less particulate matter. We also use third-party cookies that help us analyze and understand how you use this website. You can think of the DPF as soot trap. The key part of the system is the EGR valve. For used vehicles, example monthly payments are based on : 48 month term, 15% deposit and 10,000 miles/year. As the name implies, their role is to inject diesel fuel into the engine cylinders at high pressures. When the time to replace the DPF comes, it will typically cost between £500 and £1500. These cookies will be stored in your browser only with your consent. It also protects the drivetrain from torsional vibrations. Low Mileage Reason in Brand New Car. It drove less than 5,000 miles a year over the course of its life. Keep in mind that this option is illegal because it increases emissions. js = d.createElement(s); js.id = id; The problem with this is that a lean mixture is difficult to ignite, and it may increase combustion temperatures to dangerous levels, high enough to melt engine pistons in severe cases. Pilot injections were possible too (by using two springs)! Ex Demo & Low Mileage Used Cars Browse fantastic deals on ex demo and low mileage used cars from a huge range of manufacturers and dealerships. In a diesel car, you can treat the dual-mass flywheel as a consumable item. Explore Diesel cars for sale as well! Trade-in, One Owner, Non-smoker, Local, Low Mileage! At this point, the car needs to be taken to a specialist to perform a forced regeneration (also called service regeneration). This means key car components can expect to enjoy a longer life, as dependin… However, if you bear with me until the end, you will learn: why diesel engines are more efficient than petrol engines, why diesel emissions became a problem for manufacturers and drivers, what typically fails in diesel engines and how much it costs to fix, if driving a diesel car makes sense for you. Pay for them in cash (if at all possible) to avoid incurring interest payments on a loan. Increasing the exhaust temperature is done by injecting extra fuel into the exhaust, where it burns. Food for thought – let me know what you think in the comments section! Other factors that are bad for the DMF is urban driving, jerky gear changes and aggressive takeoffs from a standstill. A brand new manifold should be safe for quite a while. This happens only during low and medium engine loads. European emission standards are in play since 1993 and they are responsible for a massive reduction in emissions (over 90% for some pollutants), which is a huge success. Replacing a DPF can cost over 1,500 Euros for the part, before labour costs are added. Buying a car with an inordinately low mileage. Some of these components have relatively short lifespans, which is the source of the high maintenance cost of diesel engines. Today, we’ve got fuel injection systems that run at pressures high enough to cut through things. Everything was purely mechanical and such engines were still used in passenger cars in the 1990s. It’s just that dual-mass flywheels do it better. However, it is also illegal in the UK and probably in most other countries. Time will tell how reliable the SCR systems are and how long they will last. Incorrect tire pressure is a common cause of bad gas mileage. Euro 5 (new cars registered from 1 January 2011) – the use of diesel particulate filters became mandatory. This 2020 Ram 1500 is for sale today. Also, diesel engines can operate at higher boost pressures than petrol engines because too much boost (or too high compression ratio) makes petrol engines susceptible to destructive knocking (detonation). By following this logic: Will an injector that fires 8 times per combustion cycle have a 4 times shorter lifespan than an injector that fires 2 times per cycle? Swirl flap failure is a common problem in diesel engines and the main cause is the EGR valve. The extra CO2 emitted by cars with particulate filters is the lesser evil when compared to the particulate matter that gets burned away. They may also slightly improve engine torque at low revs. A 2500 bar fuel injector will throw a hissing fit very quickly when fed anything else than good quality, perfectly clean diesel fuel. When you step on the gas, the EGR valve should close, as long as it’s not stuck. diesel car for low mileage – recommended or not? The particulate matter needs to be burned off before the DPF becomes full. Your email address will not be published. The engine is even aesthetically perfect. var js, fjs = d.getElementsByTagName(s)[0]; Bought a new car, wondering why is the mileage so low in a Brand New Car as against claimed Mileage by Company in between 20 Kmpl to 25 Kmpl. Air-fuel ratios only become important, when you take engine emissions into account. How is it supposed to work reliably when it’s full of soot? This is indicating your DPF is full and the engine computer was not able to complete the regeneration.