add option to temperature compensate alpha-n

firmware/controllers/algo/airmass/alphan_airmass.cpp

@@ -13,11 +13,17 @@ AirmassResult AlphaNAirmass::getAirmass(int rpm, bool postState) {
 	// In this case, VE directly describes the cylinder filling relative to the ideal
 	float ve = getVe(rpm, tps.Value, postState);
 
+	// optionally use real IAT instead of fixed air temperature
+	constexpr float standardIat = 273.0f + 20.0f;	// std atmosphere temperature
+	float iat = engineConfiguration->alphaNUseIat
+		? Sensor::get(SensorType::Iat).value_or(standardIat)
+		: standardIat;
+
 	// TODO: should this be barometric pressure and/or temperature compensated?
 	mass_t airmass = getAirmassImpl(
 		ve,
 		101.325f,		// std atmosphere pressure
-		273.0f + 20.0f	// std atmosphere pressure
+		iat
 	);
 
 	return {

firmware/integration/rusefi_config.txt

@@ -844,7 +844,7 @@ sensor_chart_e sensorChartMode;rusEFI console Sensor Sniffer mode;
 	bit enableSoftwareKnock
 	bit verboseVVTDecoding;Verbose info in console below engineSnifferRpmThreshold\nenable vvt_details
 	bit invertCamVVTSignal;get invertCamVVTSignal
-	bit unused804b12
+	bit alphaNUseIat;In Alpha-N mode, compensate for air temperature.
 	bit knockBankCyl1,"Channel 2","Channel 1"
 	bit knockBankCyl2,"Channel 2","Channel 1"
 	bit knockBankCyl3,"Channel 2","Channel 1"

firmware/tunerstudio/rusefi.input

@@ -2186,6 +2186,7 @@ cmd_set_engine_type_default					= "@@TS_IO_TEST_COMMAND_char@@@@ts_command_e_TS_
 		field = "Enabled",						isInjectionEnabled
 		field = "Mode",							injectionMode, {isInjectionEnabled == 1}
 		field = "#Batch injection with individual wiring"
+		field = "Alpha-N uses IAT density correction",	alphaNUseIat, { fuelAlgorithm == @@engine_load_mode_e_LM_ALPHA_N@@ }
 		field = "Override VE table load axis",			veOverrideMode, { isInjectionEnabled }
 		field = "Override AFR table load axis",			afrOverrideMode, { isInjectionEnabled }
 		field = "Injection phase control mode",				injectionTimingMode, { isInjectionEnabled }