Engine 1 Data

Engine Speed-Range (0-16384 RPM): The VCM computes the Engine Speed from the fuel control reference input. The speed should remain close to the desired idle under the various engines loads with the engine idling.

Desired Idle Speed-Range (0-3187 RPM): The VCM commands the desired IAC. The VCM compensates for various engine loads in order to maintain the desired idle speed.

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

Desired IAC Position-Range (0-255) Counts: The desired IAC indicates the desired IAC position.

Throttle Position (TP) Sensor-Range (0.0-5.0 Volts): The VCM uses the Throttle Position in order to determine the amount of throttle demanded by the operator of the vehicle. The TP sensor reads between 0.36-0.96 volts at idle to above 4.0 volts at Wide Open Throttle (WOT).

TP Angle-Range (0-100%): The VCM computes the TP Angle from the TP signal voltage input. The TP Angle should read 0% at idle. AT 0%, the TP voltage will read below 0.90 volts. The TP Angle should read 100% at Wide Open Throttle.

Start Up ECT-Range 40°-215°C (-40°419°F): When the engine is started, the VCM records the engine coolant temperature. The VCM uses the recorded temperature in order to calculate the time to a Closed Loop.

ECT-Range -40°-215°C (-40°-419°F): The Engine Coolant Temperature (ECT) sensor is mounted in the intake the intake manifold. The ECT sends the engine temperature information to the VCM. The VCM supplies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes the internal resistance as the temperature changes. When the sensor is cold meaning the internal resistance is high, the VCM monitors a high voltage signal. The VCM interprets the high voltage signal as a cold engine. As the sensor warms meaning the internal resistance decreases, the voltage signal decreases. The VCM interprets the lower resistance as a warm engine.

ECT Sensor-Range (0.0-5.0 Volts): The Engine Coolant Temperature (ECT) sensor is mounted in the intake the intake manifold. The ECT sends the engine temperature information to the VCM. The VCM supplies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes the internal resistance as the temperature changes. When the sensor is cold meaning the internal resistance is high, the VCM monitors a high voltage signal. The VCM interprets the high voltage signal as a cold engine. As the sensor warms meaning the internal resistance decreases, the voltage signal decreases. The VCM interprets the lower resistance as a warm engine.

Manifold Absolute Pressure (MAP) Sensor-Range (0.0-5.0 Volts) : The MAP sensor produces a low signal voltage when the manifold pressure is low. A low manifold pressure means a high vacuum. The MAP sensor produces a high signal voltage when the manifold pressure is high. A high manifold pressure means a low vacuum. With the ignition ON and the engine stopped, the manifold pressure equals the atmospheric pressure causing the signal voltage to be high. The VCM uses this information as an indication of the vehicle's altitude. This information is referred to as the BARO. Comparison of this BARO reading with a known good vehicle with the same sensor is a good way to check accuracy of a suspect sensor. The readings should read the same +0.4 volt.

Manifold Absolute Pressure (MAP)-Range (10 kPa-104 kPa): The Manifold Absolute Pressure (MAP) sensor measures the change in the intake manifold pressure from the engine load and the speed changes. As the intake manifold pressure increases, the air density in the intake manifold also increases. Additional fuel is required.

Barometric Pressure (BARO)-Range (0.0-5.0 Volts): The BARO represents a measurement of the barometric air pressure. This measurement is determined by using the Manifold Air Pressure (MAP) sensor in order to determine the manifold vacuum. Since the barometric air pressure depends on the altitude, the measurement may vary from 100 kPa (sea level) to 60 kPa (14,000 ft.).

Barometric Pressure (BARO) Sensor-Range (0-62 kPa): The VCM determines the displayed BARO reading from the MAP sensor at the ignition ON and the engine OFF and the WOT conditions. The BARO reading displayed represents the barometric pressure. The VCM uses the displayed BARO readings in order to compensate for the altitude differences.

Start-up IAT-Range (-40°-151°C): The VCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees. The VCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

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

Intake Air Temperature (IAT) Sensor-(0.0-5.0 Volts): The VCM converts the resistance of the Intake Air Temperature (IAT) sensor to degrees. The VCM uses the intake air temperature in order to adjust the fuel delivery and the spark timing according to the incoming air density.

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

MAF Frequency (Hertz): The VCM converts the Mass Air Flow sensor input signal into grams per second or hertz. The MAF indicates the amount of air entering the engine.

Engine Load-Range (0-100%): The VCM determines the engine load based upon the engine speed and MAF sensor readings. Engine Load increases with any increase in RPM and/or airflow.

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

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

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

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

Short Term Fuel Trim (FT) Bn 1-Range (0-255 Counts): The short term fuel trim was formerly the fuel integrator. The short term fuel trim represents a short-term correction to the fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. A HO2S voltage reading below 450 mV indicates a lean air to fuel mixture. If the HO2S voltage has mainly been below 450 mV threshold, the short term fuel trim increases in order to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM reduces the fuel delivery in order to compensate for the indicated rich condition.

Short Term Fuel Trim (FT) Bn 1-Percentage of Compensation Required: The short term fuel trim was formerly the fuel integrator. The short term fuel trim represents a short-term correction to the fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. A HO2S voltage reading below 450 mV indicates a lean air to fuel mixture. If the HO2S voltage has mainly been below 450 mV threshold, the short term fuel trim increases in order to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM reduces the fuel delivery in order to compensate for the indicated rich condition.

Short Term Fuel Trim (FT) Bn 2-Range (0-255 Counts): The short term fuel trim was formerly the fuel integrator. The short term fuel trim represents a short-term correction to the fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. A HO2S voltage reading below 450 mV indicates a lean air to fuel mixture. If the HO2S voltage has mainly been below 450 mV threshold, the short term fuel trim increases in order to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM reduces the fuel delivery in order to compensate for the indicated rich condition.

Short Term Fuel Trim (FT) Bn 2-Percentage of Compensation Required: The short term fuel trim was formerly the fuel integrator. The short term fuel trim represents a short-term correction to the fuel delivery by the VCM in response to the amount of time the HO2S voltage spends above or below the 450 mV threshold. A HO2S voltage reading below 450 mV indicates a lean air to fuel mixture. If the HO2S voltage has mainly been below 450 mV threshold, the short term fuel trim increases in order to tell the VCM to add fuel. If the HO2S voltage stays mainly above the threshold, the VCM reduces the fuel delivery in order to compensate for the indicated rich condition.

Engine Speed-Range 0-16384 RPM: The VCM computes the Engine Speed from the fuel control reference input. The speed should remain close to the desired idle under the various engines loads with the engine idling.

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

Fuel Trim Enable-Range (ON/OFF): The Fuel Trim Enable indicates the state of the fuel trim (Enable/Disabled) that the VCM is commanding. Fuel trim will be disabled when the vehicle is not in closed loop, malfunction codes related to fuel trim are set, large amounts of purge vapor are injested by the engine, or additional diagnostics that temporarily affect fuel trim operation are active.

EVAP Canister Purge-OFF/ON: The EVAP Canister Purge pulls a small vacuum on the entire evaporative emission system. The scan tool displays if the EVAP Canister Purge Solenoid Valve is currently OFF or ON. When the scan tool displays ON, the small vacuum is being applied.

[1][2]EVAP Duty Cycle-Range (0-100%): The scan tool indicates the EVAP duty cycle that the VCM is commanding. The EVAP duty cycle is a pulse modulated signal which is translated into a direct percentage of the maximum commandable state.

EGR Duty Cycle-(0%-100%): The EGR Duty Cycle determines a percentage of time the valve is being opened and closed.

Actual EGR Position-Range (0-100%): The Actual EGR Position indicates the actual EGR position in a percentage.

Desired EGR Position-Range (0-199.9%): The Desired EGR Position indicates the desired EGR position in a percentage.

EGR Sensor-Range (0.0-5.00 Volts): The EGR Sensor indicates the actual EGR position in voltage.

Vehicle Speed-km/h-Range (0-255): The MPH-km/h indicates in MPH and in km/h how fast the drive wheels are turning.

Ref. Pulse Occurred-Range (Yes/No): The scan tool will indicate a Yes for up to 1 second after a reference pulse has been detected by the CKP.

Valid Ref. Pulse Occurred-Range (Yes/No): The scan tool will indicate a Yes after 2 or more reference pulses have been detected by the CKP.

Knock (KS) Sensor-Range (0.0-5.0 Volts): The scan tool indicates the current knock sensor voltage.

Knock (KS) Sensor Activity-Range (0-255 Counts): The Knock Sensor Activity indicates the amount of spark knock the VCM detects.

Spark-Range (-96 Degrees to-255 Degrees): The Spark Advance is a display of the spark advance calculation which the VCM is programming into the ignition system. The VCM computes the desired spark advance using data such as the engine temperature, the RPM, the load, the vehicle speed, and the operating mode.

Knock Retard-Range (0.0-90 Degrees): The KS Retard indicates the amount of spark advance is the VCM removes in order to diminish spark knock.

CMP Retard-Range (0.0-90 Degrees): The CAM Retard indicates the difference between the CMP sensor and the CKP sensor relationship.

Spark Control-Range (Advance Retard): The Spark Control indicates whether the VCM is advancing or retarding spark.

Loop Status-Range (Open/Close): The Loop Status indicates that the VCM is controlling fuel delivery according to HO2S input. During open loop, the VCM ignores the HO2S input and bases fuel delivery upon TP, engine coolant, and MAF sensor input.

Pre HO2S (Not Ready/Ready): The scan tool will display the current state of the HO2S system.

Post HO2S (Not Ready/Ready): The scan tool will display the current state of the HO2S system.

Rich/Lean Bn 1-(Rich/Lean): The Rich/Lean Bn 1 indicates the condition of the exhaust gases in bank 1.

Rich/Lean Bn 2-(Rich/Lean): The Rich/Lean Bn 2 indicates the condition of the exhaust gases in bank 2.

Ignition 1-Range (0.0-25.5 Volts): The Ignition 1 indicates the voltage of the ignition input to the VCM.

Air Fuel Ratio-Range (0.0:1-25.5:1): The scan tool indicates the VCM calculated air to fuel ratio. The typical air to fuel ratio is 14.7:1.

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