December/January 2022

DECEMBER/JANUARY 2022 AFTERMARKET 31 Fig 1 can also lead to fuel filter restriction and sump oil contamination, requiring a shorter servicing regime. Significantly, it is not universally approved by all manufacturers either, especially with regards to older vehicles. Benefit In my opinion, vehicles constantly used within this environment i.e., 250-500 miles a month, and that includes a high number of diesel owners, would benefit from flushing and an oil service every three to six months. That statement may sound ridiculous today, but it will not tomorrow. I have often argued that many vehicle owners cannot afford to maintain their cars correctly, adding to an already problematic fuel system. In addition, many budget service parts on offer do not meet the design criteria set out by the vehicle manufacturers. Air, oil and DPF filtration directly affects the particulates so often discussed by environmentalists. Diesel engines, by nature and design, operate with an excess air ratio. I often wonder how this is affected by inefficient filtration and intake system contamination. Have you ever considered the impact on volumetric efficiency from the oil contamination in the intercooler? Or the reduction in measured air mass from air mass meter contamination? Both of these are critical to SCR reduction calculations. When conducting a repair or basic service do you check for DTCs, or more importantly, deviation or correction values? These are often stored without a DTC as the required threshold has not been reached. Innovation Part two of this topic will look in detail at catalytic and additive reduction systems which rely on accurate calculation of clean air intake, EGR, temperature, and many other input values. Gasoline and diesel engines now share the same technological innovations, seeking ever better power delivery with reduced emissions. Extremely high compression ratios demand the ability to alter the valve open and closed periods either side of TDC in order to improve volumetric efficiency and reduce pumping losses. For example, by opening the intake valve early during the exhaust, stroke will improve internal EGR efficiency, coupled with EGR cooling further reducing NOx. Fig 2 Lower combustion temperatures can lead to injector fouling and small increases in NOx ” Next issue: Diesel emissions: Part Two will look at the complete DPF and SCR systems, with useful repair and service advice courtesy of Frank ssociation ent A quipm ge E a e Gar Th 5 e 194 c ds sin dar y stan dustr s of In older e Uph d ! r ation c edit r or his ac f gin our en y Ask eer c a IS Y . Y ent A For peace of mind always use a Garage Equipm ssociation member. GEA accredited engineers work to an industry code of conduct our assurance their skills and knowledge have been independently assessed. OUR EQUIPMENT ENGINEER GEA ACCREDITED? Th www.gea.co.uk GEA ACCREDITED ENGINEER Name Company Discipline ExpDate IDNumber XX123456 XX123456 XX123456 XX123456 XX123456