Intake Air Temperature (IAT)

The temperature of air entering the engine, used to correct air-density calculations and trigger heat-related timing and fuel adjustments.

Intake air temperature (IAT) is the temperature of the air entering the engine, read by a sensor in the intake tract or built into the MAF. Because air density falls as temperature rises, the PCM uses IAT to correct airflow and fueling math; in speed density it feeds the ideal-gas calculation directly, and it also drives IAT-based timing retard to protect against knock on hot air. It matters for a safe tune because ignoring heat soak or boost-heated intake air leads to over-advanced timing and detonation, while bad IAT scaling skews every density-corrected airflow estimate. In HP Tuners VCM Editor, IAT-based corrections live under Engine > Airflow and the spark/timing tables (IAT retard maps). In VCM Scanner you log IAT alongside MAP, knock retard, and wideband AFR, especially during back-to-back pulls, to confirm the engine pulls timing sensibly as charge temperature climbs rather than running into knock.