June 2020

BY Frank Massey I ’m sure none of us could have foreseen just where we are today, no more than it is possible to predict where the future will take us. We can, I believe, have confidence in several probabilities. The future requirement for vehicle repair and servicing is high quality work, and I predict an even more discerning demand from the public for skilful independents to provide that service. It is inevitable that some businesses will cease trading, with the loss of employment for many skilful technicians. The market will find its own natural level, and I do not think artificial stimulation will change it. This is, however, the pivotal moment when professionally structured, financed and client-focused businesses will take pole position, and find the opportunities in our future. As for now, it hurts and hurts a lot. So, lets re-focus for a moment on those skills which will be essential. We hear daily the vital importance of testing and the evidence led by science which will result in the quickest possible success. It is this message I and others have applied to vehicle diagnostics for the last few decades. I hope now it may convince other sceptical techs how vital it is. So, I’m going to reflect on the past, present and future with this topic on combustion problems. For the sake of accuracy, it is better not to use the term misfire. Rather, go with ‘combustion anomaly’. This 26 AFTERMARKET JUNE 2020 TECHNICAL www.aftermarketonline.net COMBUSTION PAST, PRESENT AND FUTURE Combustion problems have been with us since the dawn of the internal combustion engine, and they continue to occur as technology changes description is broad enough to include a combination of mechanical, ignition, and fuel delivery options. As to the cause? This can be, and often is, intermittent in nature. The past provided options which sadly have been dismissed by many of today’s techs. These ranged from the obvious visual inspection of the sparking plug to just listening to the combustion note in the exhaust, where combustion transients could clearly be detected. These were usually associated with fuel quantity, atomisation and flame spread. More on that later. One of the greatest assets was four gas analysis. This was an acquired art, the bible for all discerning tuners. Has it been stolen? Have we lost it? Where has it gone? It is still there, you just need to know where to look. It is hidden, often disguised in the belief that onboard diagnostics will find problems for us. It would be a mistake to rely entirely on that process, so Back To The Future McFly! Gases Why not drill the pre-cat manifold, install a rivet nut and install a hose ferrel? Now you can blow the dust off your four or five gas analytical skill. Interesting fact: The expression lambda is taken from a mathematical calculation of the four key gases; CO, HC, CO2, O2, (splint calculation). PART ONE