Engine 2 Data

Engine Scan Tool Data Definitions
This information will assist you in tracking down emission or driveability problems since the displays can be viewed while the vehicle is being driven. Refer to the Powertrain OBD System Check for additional information. Testing and Inspection

Engine Speed - Range (0 - 18384 RPM): Engine Speed is computed by the VCM from the fuel control reference input. It should remain close to the desired idle under various engine loads with the engine idling.

Desired Idle - Range (0 - 3187 RPM): The idle speed that is commanded by the VCM. The VCM will compensate for various engine loads to maintain the desired idle speed.

IAC Position - Range (0 - 255): The Idle Air Control (IAC) pintle position commanded from the VCM is displayed in counts. The greater the number of counts, the greater the command idle speed (air passages opened). Idle air control should respond fairly quickly to changes in engine load to maintain desired idle RPM.

Desired IAC - Range (0 - 255): This indicates the desired IAC position.

Front HO2S - Range (Ready - Not Ready): Indicates the status of HO2S (Bank 1 Sensor 1).

Rear HO2S - Range (Ready - Not Ready): Indicates the status of HO2S (Bank 2 Sensor 1).

HO2S BN 1 Sen. 1 - Range (0 - 1107 mV): Indicates the activity of HO2S (Bank 1 Sensor 1).

HO2S BN 2 Sen. 1 - Range (0 - 1107 mV): Indicates the activity of HO2S (Bank 2 Sensor 1).

HO2S BN 1 Sen. 2 - Range (0 - 1107 mV): Indicates the activity of HO2S (Bank 1 Sensor 2).

HO2S BN 1 Sen. 3 - Range (0 - 1107 mV): Indicates the activity of HO2S (Bank 1 Sensor 3).

HO2S BN 2 Sen. 2 - Range (0 - 1107 mV): Indicates the activity of HO2S (Bank 2 Sensor 2).

HO2S X counts BN 1 - Range (0 - 255): Indicates the number of times that HO2S (Bank 1 Sensor 1) crosses a threshold.

HO2S X counts BN 2 - Range (0 - 255) Indicates the number of times that HO2S (Bank 2 Sensor 1) crosses a threshold.

Long Term Fuel Trim FT BN 1 - Range (0 255) (-100% - 100%): Long Term Fuel Trim (FT) is derived from the short term fuel trim value and is used for long-term correction of fuel delivery. A
value of 128 counts (0%) indicates that fuel delivery requires no compensation to maintain a 14.7:1 air/fuel ratio. A value below 128 counts means that the fuel system is too rich and fuel delivery is being reduced (decreased injector pulse width). A value above 128 counts indicates that a lean condition exists and the VCM is compensating by adding fuel (increased injector pulse width).

Long Term Fuel Trim FT BN 2 - Range (0 - 255) (-100% - 100%): Long Term Fuel Trim (FT) is derived from the short term fuel trim value and is used for long-term correction of fuel delivery. A value of 128 counts (0%) indicates that fuel delivery requires no compensation to maintain a 14.7:1 air/fuel ratio. A value below 128 counts means that the fuel system is too rich and fuel delivery is being reduced (decreased injector pulse width). A value above 128 counts indicates that a lean condition exists and the VCM is compensating by adding fuel (increased injector pulse width).

Short Term Fuel Trim FT BN 1 - Range (0 - 255) (-100% - 100%): Short term fuel trim (formerly fuel integrator) represents a short-term correction to fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. If the HO2S voltage has mainly been below 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM will reduce fuel delivery to compensate for the indicated rich condition.

Short Term Fuel Trim FT BN 2 - Range (0 - 255) (-100% - 100%): Short term fuel trim (formerly fuel integrator) represents a short-term correction to fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. If the HO2S voltage has mainly been below 450 mV, indicating a lean air/fuel mixture, short term fuel trim will increase to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM will reduce fuel delivery to compensate for the indicated rich condition.

FT Cell BN 1 - Range (0 - 255): Fuel Trim Cell is dependent upon engine speed and MAP sensor readings. A plot of RPM vs. MAP is broken down into 22 cells. Fuel Trim Cell indicates which cell is currently active.

FT Cell BN 2 - Range (0 - 255): Fuel Trim Cell is dependent upon engine speed and MAP sensor readings. A plot of RPM vs. MAP is broken down into 22 cells. Fuel Trim Cell indicates which cell is currently active.

Rich/Lean BN 1 - Range (Rich/Lean): Indicates the condition of the exhaust gases in bank 1. Rich/Lean BN 2 - Range (Rich/Lean): Indicates the condition of the exhaust gases in bank 2.

Loop Status - Range (Open/Closed): Indicates what mode of operation the VCM is in.

DTC Counter - Range (0 - 255): This indicates the total number of current Diagnostic Trouble Codes (DTCs) set. This does not necessarily mean the Malfunction Indicator Lamp (MIL) is illuminated.

Engine Run Time - Range (0:00:00 - 18:12:15) Hours: Minutes: Seconds: This is a measure of how long the engine has been running during this ignition cycle. When the engine stops running, the timer is reset to zero.

Long Term FT Range (Disabled/Enabled): Indicates if the long term Fuel Trim (FT) is disabled or enabled.

IAT - Range (40°C to 151°C): The VCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees. Intake air temperature is used by the VCM to adjust fuel delivery and spark timing according to incoming air density.

MAF - Range 0 - 512 g/s: The VCM converts the Mass Air Flow sensor input signal into grams per second, indicating the amount of air entering the engine.

ECT Sensor - Range (0 - 5.0V): The Engine Coolant Temperature (ECT) sensor is mounted in the intake manifold and sends engine temperature information to the VCM. The VCM supplies 5V to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold (internal resistance high), the VCM monitors a high voltage signal which it interprets as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal will decrease and the VCM will interpret the lower voltage as a warm engine.

Start Up ECT - Range -40°C to 215°C (40°F to 419°F: When the engine is started the engine coolant temperature is recorded by the VCM. This information is used to calculate the time to closed loop.

Ignition 1 - Range (0.0 - 25.5V): Indicates the condition of the ignition input to the VCM. Air/Fuel Ratio - Range (0.0:1 - 25.5:1) (5.7L, 7.4L Only): Indicates the calculated Air/Fuel ratio that is being commanded by the VCM.

Spark Control - Range (Advance - Retard): Indicates if the VCM is commanding spark advance or spark retard.

Engine Load - Range (0 - 100%): This indicates the engine load based on Manifold Absolute Pressure. The higher the percentage, the more load the engine is under.