Fuel trim is related to the feedback compensation value, not to the basic injection time. Fuel trim includes short–term fuel trim and long–term fuel trim. Short–term fuel trim is the short–term fuel compensation used to maintain the air–fuel ratio at its ideal theoretical value. The signal from the A/F sensor is approximately proportional to the existing air–fuel ratio, and ECM compares it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air–fuel ratio is RICH and increases fuel volume if it is LEAN. Long–term fuel trim compensates for the deviation from the central value of the short–term fuel trim stored by each engine tolerance, and the deviation from the central value due to the passage of time and changes of environment. If both the short–term fuel trim and long–term fuel trim exceed a certain value, it is detected as a malfunction and the MIL lights up.
Showing posts with label dtc. Show all posts
Showing posts with label dtc. Show all posts
Wednesday, June 2, 2010
2002 Toyota Tacoma System too Lean (Fuel Trim) Engine Diagnostics
2:41 AM by onesecond
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Labels: actual air, af1, air fuel ratio, bank 1, dtc, engine diagnostics, injection time, lean side, obd ii scan tool, output voltage, p0171, passage of time, sensor output, tacoma system, theoretical value, tolerance, Toyota, toyota tacoma
Labels: actual air, af1, air fuel ratio, bank 1, dtc, engine diagnostics, injection time, lean side, obd ii scan tool, output voltage, p0171, passage of time, sensor output, tacoma system, theoretical value, tolerance, Toyota, toyota tacoma
Saturday, May 29, 2010
2005 Ford Taurus Engine Controls Vacuum Leakage Noise Possible DTC's
11:30 PM by onesecond
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Labels: 0l, 2005 ford taurus, actuator, diagnosis, dtc, electrical connector, engine oil, Ford, ford taurus, indicator lamp, intake manifold, Lincoln, lincoln ls, procedure steps, retainers, sable, upper intake manifold, vacuum, valve action
Labels: 0l, 2005 ford taurus, actuator, diagnosis, dtc, electrical connector, engine oil, Ford, ford taurus, indicator lamp, intake manifold, Lincoln, lincoln ls, procedure steps, retainers, sable, upper intake manifold, vacuum, valve action
Some 2005 Taurus and Sable vehicles equipped with a 3.0L 2V and some 2003-
2005 Lincoln LS vehicles equipped with a 3.0L 4V engine may exhibit a vacuum
leakage noise or lean codes and/or malfunction indicator lamp (MIL) on. The
cause may be a leak at the 0-ring on the intake manifold tuning (IMT) valve.
ACTION
Follow the Service Procedure steps to correct the condition.
2005 Lincoln LS vehicles equipped with a 3.0L 4V engine may exhibit a vacuum
leakage noise or lean codes and/or malfunction indicator lamp (MIL) on. The
cause may be a leak at the 0-ring on the intake manifold tuning (IMT) valve.
ACTION
Follow the Service Procedure steps to correct the condition.
2000-2003 Ford Taurus Idle Air Control (IAC) Valve Diagnostics Service Tips
9:49 PM by onesecond
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1 comments
Labels: accurate identification, crank, dtc, engine stall, Ford, ford taurus, hesitation, idle speed control, indicator lamp, service writer, steady speed, time source, valve diagnostics
Labels: accurate identification, crank, dtc, engine stall, Ford, ford taurus, hesitation, idle speed control, indicator lamp, service writer, steady speed, time source, valve diagnostics
Some vehicles, may exhibit drivability conditions. These may include: • No start • Difficult to start • Stall • Low idle • Rough idle • High idle • Hesitation/surge while accelerating or at steady speed
These conditions may be intermittent with no Diagnostic Trouble Codes (DTC) and no Malfunction Indicator Lamp (MIL). In some cases DTC and MIL may be evident.
These conditions may be intermittent with no Diagnostic Trouble Codes (DTC) and no Malfunction Indicator Lamp (MIL). In some cases DTC and MIL may be evident.
Saturday, May 15, 2010
2000-2002 G20 Mil ON Rear O2 Sensor DTC
10:04 PM by onesecond
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0
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Labels: bank 1, diagnosis results, dtc, dtcs, ecm, figure 1, high voltage, Infiniti, max voltage, o2 sensor, oxygen sensor, self diagnosis
Labels: bank 1, diagnosis results, dtc, dtcs, ecm, figure 1, high voltage, Infiniti, max voltage, o2 sensor, oxygen sensor, self diagnosis
If a 2000 to 2002 G20 has a MIL "On" and any of the following DTCs stored in the ECM:
• P0138 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Max. Voltage Monitoring)
• P0139 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Response Monitoring)
• P0140 Heated Oxygen Sensor 2 (Rear) (Bank 1) (High Voltage)
Start with the Service Procedure to find out if the bulletin applies to this vehicle. If it does apply, complete the Service Procedure to repair the incident, if it should occur.
• P0138 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Max. Voltage Monitoring)
• P0139 Heated Oxygen Sensor 2 (Rear) (Bank 1) (Response Monitoring)
• P0140 Heated Oxygen Sensor 2 (Rear) (Bank 1) (High Voltage)
Start with the Service Procedure to find out if the bulletin applies to this vehicle. If it does apply, complete the Service Procedure to repair the incident, if it should occur.
2003 Saturn L300 V6-3.0L VIN R P2119-Throttle Closed Position Performance
7:08 AM by onesecond
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Labels: 0l, 2003 saturn l300, amount of time, circuit faults, dtc, ecm, parameters, plate position, rest position, return spring, Saturn, saturn l300, tac, throttle plate, throttle position sensors, tp, vin
Labels: 0l, 2003 saturn l300, amount of time, circuit faults, dtc, ecm, parameters, plate position, rest position, return spring, Saturn, saturn l300, tac, throttle plate, throttle position sensors, tp, vin
The throttle actuator control (TAC) module contains a direct current actuator motor
controlled by the ECM used to move the throttle plate (in either direction) and two throttle
position sensors to determine throttle plate position. The throttle plate is held at a 7% rest
position to a mechanical stop by a constant force return spring. This spring will hold the
throttle plate to the stop when there is no current flowing to the actuator motor. There is
another return spring, which creates constant force on the throttle plate only when the
throttle plate is moved towards the full closed position. The ECM will monitor both the
actuator motor and TP sensors for circuit faults, as well as check to make sure both
springs can return the throttle to the 7% position no matter where the throttle plate
remains.
controlled by the ECM used to move the throttle plate (in either direction) and two throttle
position sensors to determine throttle plate position. The throttle plate is held at a 7% rest
position to a mechanical stop by a constant force return spring. This spring will hold the
throttle plate to the stop when there is no current flowing to the actuator motor. There is
another return spring, which creates constant force on the throttle plate only when the
throttle plate is moved towards the full closed position. The ECM will monitor both the
actuator motor and TP sensors for circuit faults, as well as check to make sure both
springs can return the throttle to the 7% position no matter where the throttle plate
remains.
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