DECEMBER/JANUARY 2024 AFTERMARKET 27 Please refer to Fig.7, which shows the intake ports, and Fig.8 showing the throttle valve and MAP sensor. With my engineering background I don’t take to compromise easily. My preferred option was head off, complete decoke, new injectors, EGR, EGR cooler and DPF. Instead, I was left with the in-situ option. It took an awfully long time and was messy even with great care, and there is always the problem of cylinder fouling even with closed valves. We received some additional information regarding this problem and vehicle type relating to turbo failure following decoke repairs. In fact, it is confirmed on the manufacturers service repair bulletins. My thoughts on this issue lean towards likely oil fuel contamination due to excessive regeneration cycles. More probable is a restricted map sensor; This would reduce the feedback manifold pressure, possibly causing to turbo to over boost. The owner did explain that when used as a company vehicle over frequent distance journeys the car performed without any issues. The car was then passed to his wife who only used it for short trips. Clean diesel technology is theoretically sound. In practical terms though they are very expensive both to service and repair. I always advocate performance fuel B5 not B7 and regular oil changes in keeping with usage profile. We now have low and high pressure EGR valves as well as an exhaust flow regulation valve. Exhaust coolers and additive injectors are often problematic though. One last word of advice; Always check your urea; 32.5% concentration no more, no less. It needs to be stored in a very particular way to keep it in good health too. Naturally, most retail garages store outside it in direct sunlight, then leave it out in the frost in winter. Then again, if it works for the screenwash, why treat this any differently? www.aftermarketonline.net Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8
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