Low-cost wireless sensors embedded in machines and plant floors are essential components for intelligent monitoring and automation in automated manufacturing systems. To enable robust and confident industrial adoption of wireless sensor systems, their data transmission performance must be guaranteed before deployment. Moving objects such as forklifts in common manufacturing settings are known to cause errors and losses in wireless sensor data transmission. As an essential step toward building wireless sensor-based manufacturing plant floor monitoring systems, this study has conducted systematic data transmission performance measurements with IEEE 802.15.4 sensors in the presence of a moving forklift. It is found that for a typical moving forklift, its path loss profile can be predicted based on its stationary path loss profile. Specifically, the path loss for a moving forklift can be adequately modeled using a two-state time-dependent model with both deterministic and random contributions. Such a two-state path loss model can be applied to adequately estimate the packet error rate in the presence of moving objects.