Fuel

Cleaned MAF sensor and long term fuel trim dropped to -10%

Cleaned MAF sensor and long term fuel trim dropped to -10%
  • 2258
  • John Lloyd
  1. What affects long term fuel trim?
  2. What does it mean when your long term fuel trim is?
  3. What causes low fuel trim?
  4. How do I reset my long term fuel trim?
  5. What should my long term fuel trim idle?
  6. Why is my long term fuel trim so high?
  7. What causes negative Ltft?
  8. What causes fuel trim malfunction 1?
  9. How do you fix fuel system too rich?
  10. What is short-term fuel trim bank1?
  11. How do I fix my fuel trim Bank 2?

What affects long term fuel trim?

Long Term Fuel Trim

Long-term fuel trim relies on sensors further downstream in the exhaust system, past the catalytic converter. While the sensors' signal will fluctuate frequently upstream, where short-term fuel trim is measured, the signal at the sensors further down should be fairly constant.

What does it mean when your long term fuel trim is?

Long Term Fuel Trim (LTFT) is a longer term average of what the engine computer has been doing to balance the fuel mixture over a predetermined interval of time.

What causes low fuel trim?

During idle when the throttle plate is closed, the vacuum in the intake manifold is high and very little air flow is entering the engine, so even a small amount of un-metered air will have an effect on fuel trim. ... This causes the fuel trim numbers to become negative during a boost situation.

How do I reset my long term fuel trim?

To perform a PCM reset...

  1. Bring car up to normal operating temp.
  2. Turn ignition off.
  3. Remove ECM main fuse.
  4. Turn ignition to "on", do not start.
  5. Wait for system check to complete, numerous errors will be detected.
  6. Turn ignition off.
  7. Replace fuse.
  8. Turn ignition to "on" and wait for system check.

What should my long term fuel trim idle?

If long-term fuel trim (LTFT) for bank 1 is 25% at idle, but corrects to 4% at 1,500 and 2,500 rpm, focus on factors that cause a lean condition at idle, such as a vacuum leak.

Why is my long term fuel trim so high?

If the engine uses a mass airflow sensor (MAF), high fuel trims at idle are a classic symptom of a vacuum leak, especially if LTFT decreases at higher engine speeds. ... A dirty or faulty MAF sensor can also cause positive fuel trim numbers because it “under-reports” airflow, driving the base air/fuel calculation lean.

What causes negative Ltft?

Negative LTFT should be caused either by something wrong with the fuel system that's adding too much fuel, or not enough air flowing into the engine.

What causes fuel trim malfunction 1?

There are many conditions and factors that can cause the engine to run lean, such as a clogged fuel filter, weak fuel pump, or faulty fuel pressure. The same thing applies for rich conditions, with factors like a faulty airflow sensor manifold, faulty fuel pressure regulator, and absolute pressure sensor.

How do you fix fuel system too rich?

What repairs can fix the P0172 code?

  1. A repair of a vacuum leak.
  2. A replacement of a faulty fuel injector, fuel pump, or fuel regulator.
  3. Replacement of an excessively restricted air filter.
  4. Replacement of the thermostat or coolant temperature sensor.
  5. A replacement of the spark plugs.

What is short-term fuel trim bank1?

The short-term fuel trim (STFT) refers to immediate changes in fuel occurring several times per second. ... The long-term fuel trims (LTFT) are driven by the short-term fuel trims. LTFT refers to changes in STFT but averaged over a longer period of time.

How do I fix my fuel trim Bank 2?

What repairs can fix the P0173 code?

  1. Replacing the mass air flow sensor.
  2. Replacing the fuel pressure regulator.
  3. Replacing the intake manifold gaskets.
  4. Repairing or replacing the engine air filter intake system.
  5. Replacing a vacuum line connected to the throttle body.
  6. Repairing a leaking brake booster.

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