A measurement system is provided for a combustion engine. The measurement system employs a fiber optic cable optically coupled to a light source and has at least one Bragg grating. A second fiber optic cable is coupled to the first fiber optic cable in addition to a wavelength measurement device and a device for measuring intensity. A controller is coupled to the device for measuring intensity and the wavelength measurement device. Based upon the measurements from these devices, the controller determines the temperature and pressure in the combustion engine.