July/August 2019

BY Frank Massey I want to discuss diesel servicing from a totally different direction, compared with the usual angle. Let’s also start from a different angle, compared with the usual view. Consider this; Servicing is a failure prevention strategy. Conducted in accordance with the operating environment there should theoretically be no failures. Please note my careful choice of words, operating environment. Manufacturers always have and are still marketing their vehicles with inappropriate servicing regimes. The political focus is one based on a relatively short warranty period and tailored to business or lease company requirements. In my opinion, service intervals should reflect the operating environment rather than fixed values such as time or distance. The very activities established as suitable by the VMs fall woefully short of actual requirements. Vehicle owners are, I believe, misled by a whole group of agencies with regards to vehicle ownership and responsibilities. I also think the possibility of cradle-to-grave ownership is closer than we like to acknowledge. You rent or lease a vehicle over a two-to-three year period with all maintenance inclusive. At the end of the rental period the vehicle is exchanged with a consecutive end to end contract. No responsibilities for repair or servicing. With this in mind, how should we approach diesel servicing given the problems with premature component failure and excessive emission issues? Detailed knowledge Let’s assume we have a new customer. Our first responsibility is to understand how they operate the vehicle and their aspirations and value of operating and investing in what is the Holy Grail, i.e. reliability. Detailed knowledge of driving style, traffic environment, driving distance, fuel quality, should have a direct influence on how servicing should be applied. This would be a unique profile for this customer. Conduct a visual safety inspection, both static and raised Conduct a test drive. This may include data gathering via the serial interface EOBD offers several critical opportunities for evaluation. default flags, continuous and non-continuous faults, condition not met flags, and not least, warm up cycles, distance driven and time since last active regen cycles I would suggest a maximum nominal value of 300 miles between regen cycles. Examine the oil condition thoroughly and if necessary, have it analysed for fuel-based contamination. Evaluation Next, we move onto a more focused non-intrusive evaluation of live data. It is worth noting the following components. Mapped cooling MAF values at idle with and without EGR, pay attention to MAF response time vis EGR. A sticking or leaking EGR will slow the MAF response, this should be prompt with little or no delay Quite often the rather nondescript fault code “condition not met,” preventing active regeneration, fails to identify the specific component or function requirements. For example, during passive and active regeneration cycles, combustion temperatures can be subtly influenced if you increase engine load through activation of the heated seats 20 AFTERMARKET JULY/AUGUST 2019 TECHNICAL www.aftermarketonline.net DIESEL FROM A DIFFERENT DIRECTION Frank Massey looks at diesel servicing from another angle... Correct delivery and atomisation at 5 bar delivery pressure Fouled SCR delivery injector