Abstract: Methods and apparatus are provided for predicting ambient air temperature (PAT) around a vehicle (and partly controlling vehicle operation) based on Mass Air Flow (MAF), Vehicle Speed (VSS), Inlet Air Temperature (IAT), Engine Run Time (ERT) and the last PAT value (LPAT). If MAF,VSS are below thresholds C1, C2 and ERT is below threshold C4, then PAT is set equal to the smaller of IAT or LPAT. If MAF,VSS,ERT exceed C1, C2, C4, as for example, in steady run operation, then after an interval PAT approaches IAT?C5+/?C6 where C5 and C6 are stored parameters. An idle counter increments when MAF<C1, VSS<C2 is TRUE and decrements by parameter C3 when FALSE and must reach zero before the PAT steady run value is set. This improves prediction accuracy during transition from idle to steady state running. The PAT estimation process is repeated about every 10 seconds.

Abstract: Methods and apparatus are provided for predicting ambient air temperature (PAT) around a vehicle (and partly controlling vehicle operation) based on Mass Air Flow (MAF), Vehicle Speed (VSS), Inlet Air Temperature (IAT), Engine Run Time (ERT) and the last PAT value (LPAT). If MAF,VSS are below thresholds C1,C2 and ERT is below threshold C4, then PAT is set equal to the smaller of IAT or LPAT. If MAF,VSS,ERT exceed C1,C2,C4, as for example, in steady run operation, then after an interval PAT approaches IAT−C5+/−C6 where C5 and C6 are stored parameters. An idle counter increments when MAF<C1,VSS<C2 is TRUE and decrements by parameter C3 when FALSE and must reach zero before the PAT steady run value is set. This improves prediction accuracy during transition from idle to steady state running. The PAT estimation process is repeated about every 10 seconds.