The Wiebe function is widely used in engine simulation to estimate the MFB profile as a function of crankshaft position. In this work, for the purpose of validating a sub-process, the Wiebe function parameters were calculated using an analytical solution and a least squares method by fitting MFB locations, as determined from analysis of measured cylinder pressure, to both single and double-Wiebe functions. To determine the accuracy of the respective Wiebe function, a single-zone pressure model was applied to reconstruct the pressure trace. Once the pressure trace is recovered, the reconstructed pressure trace is then compared with the experimentally measured cylinder pressure trace. Results showed that the double-Wiebe function model fit better than the single-Wiebe function model. The root mean square error (RMSE) of the reconstructed pressure trace using the double-Wiebe estimation is 7.9?kPa. In comparison, the RMSEs of the reconstructed pressure traces using the single-Wiebe analytical solution and single-Wiebe least squares methods were 70.0?kPa and 75.9?kPa, respectively, demonstrating a significant improvement.