## 4 Conclusions  
In this study, the mapping of four frequently occurring malfunctioning conditions was performed for a large two-stroke diesel engine, by simulating and identifying their effect on the engine's flywheel ICT. The malfunctioning conditions examined were (a) change in SOI, (b) change in RHR, (c) change in scavenge air pressure and (d) blowby, which were simulated using a validated thermodynamics and crankshaft dynamics coupled engine model. In specific, changes in SOI and RHR have a nearly identical impact on the engine's in-cylinder pressure diagram, which primarily affects the maximum combustion pressure and its location. Conversely, changes in the scavenge air pressure primarily affect the compression part of the cycle, with smaller effects observed in the peak combustion pressure and its location. Most importantly changes in the scavenge air pressure affect all cylinders uniformly rather than individually, hence the impact of this malfunctioning condition on the engine performance is greater. This also differs from the effect that blowby has on the in-cylinder pressure diagram, where the combustion and expansion part of the cycle are primarily effected. As a result, the changes in SOI and RHR appear to have similar effects in the flywheel ICT, where as compared to the healthy engine conditions, a sudden change in the torque fluctuations is observed at approximately 35\({}^{\circ}\)CA after the malfunctioning cylinder reaches TDC. The delay in the change of the ICT fluctuations measured at the flywheel is a result of the crankshaft flexibility, demonstrating the importance in considering this phenomenon when considering engine dynamics to identify malfunctions in specific cylinders. The change in scavenge air pressure does not cause similar fluctuations in the flywheel ICT as all cylinders are affected uniformly, thus the crankshaft torsional stresses do not change drastically. However, when blowby occurs the flywheel ICT fluctuations are observed to change significantly at 54\({}^{\circ}\)CA after the faulty cylinder reaches TDC, and they attenuate for the rest of the engine's rotation. Subsequently, using the flywheel ICT of the malfunctioning engine conditions, a frequency analysis was performed to identify and map the harmonic frequencies with the most affected modulus and phase angle, with their corresponding malfunctioning cylinder. From this mapping process it was determined that the change in scavenge air pressure, and blowby for any malfunctioning cylinder, have a distinct effect on the flywheel ICT harmonic frequencies, and can thus be identified easily using the malfunctioning conditions map. However, the change in SOI and RHR display mostly similar effects on the flywheel ICT. Thus according to the malfunctioning conditions map it is possible to detect weather a cylinder is experiencing a change in SOI or RHR, but cannot distinguish between the two. The benefit of the malfunctions mapping approach developed in this study is that the engine model is employed only once to develop the malfunctions map, and simulate the flywheel ICT under healthy engine conditions. Subsequently, a computationally cheap and simple algorithm can be deployed in-situ which performs a frequency analysis on the flywheel ICT signal, and determines the harmonic frequencies of the most effected modulus and phase angle. As a result, in a future study the results of this process can then be readily compared with the malfunctions map to diagnose the engine's condition. Furthermore, malfunctioning conditions occurring in a combination of different cylinders can be examined and mapped in a more extensive database, that includes a larger range of malfunctioning and encompasses better the engine's realistic operating conditions. Conceptualization, K.-M.T. and G.T. ; methodology, K.-M.T. and G.T. ; software, K.-M.T. ; validation, K.-M.T. ; formal analysis, K.-M.T. ; investigation, K.-M.T. ; resources, G.T. ; data curation, K.-M.T. and G.T. ; writing--original draft preparation, K.-M.T. ; writing--review and editing, G.T.