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Cyclical exposure of a piezoelectric transducer to high temperature gas results in an error in the measured pressure due to thermal strain of the transducer diaphragm. Thermal strain results in a decrease in the measured values of IMEP and PMEP, while burn times calculated using the method of Rassweiler and Withrow are relatively unaffected. The severity of the effect can be minimized by coating the transducer diaphragm with RTV. When the effects of thermal strain persist into the intake stroke, a method of detection at low speed is to overlay and compare the firing and motoring intake stroke pressure traces.

The exhaust blowdown pulse from each cylinder of a multi-cylinder engine propagates through the exhaust manifold and can affect the in-cylinder pressure of other cylinders which have open exhaust valves. Depending on the firing interval between cylinders connected to the same exhaust manifold, this blowdown interference can affect the exhaust stroke pumping work and the exhaust pressure during overlap, which in turn affects the residual fraction in those cylinders. These blowdown interference effects are much greater for a turbocharged engine than for one which is naturally aspirated because the volume of the exhaust manifolds is minimized to improve turbocharger transient response and because the turbines restrict the flow out of the manifolds. The uneven firing order (intervals of 90°-180°-270°-180°) on each bank of a 90° V8 engine causes the blowdown interference effects to vary dramatically between cylinders.