What causes a high long term fuel trim?
What causes a high long term fuel trim? Here the PCM/ECM is basing fuel delivery on feedback from the engine’s mass airflow (MAF) or manifold absolute pressure (MAP) sensor. Any air leak that occurs AFTER these sensors is a leak that’s allowing UNMETERED air into the engine.
How long does it take for long term fuel trim to adjust?
five to 20 seconds
In general, it takes anywhere from five to 20 seconds for LTFT to change, and since it’s stored in memory when the engine is switched off, that same LTFT value is used next time the system goes into closed-loop operation.
What should my long term fuel trim be?
Long-term fuel trim values Ideally, long-term fuel trims should be at, or close to 0% when the engine is running at a steady speed. However, while changes to the engine speed will (and must) produce changes in the long-term fuel trim value, this value should return to a point close to 0% when the engine speed steadies.
What is normal long term fuel trim?
What does long term fuel trim mean?
Long Term Fuel Trim Long-term fuel trim relies on sensors further downstream in the exhaust system, past the catalytic converter. Long-term fuel trim refers to the measurements these sensors make, which are effectively an average of the modifications the ECU made as a result of short-term fuel trim.
How does long-term fuel trim work?
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 kind of fuel trim does a Toyota Corolla have?
I have a 2002 Toyota Corolla (1ZZ-FE engine) and I am trying to understand the fuel trim values I am getting in real driving conditions from my scan tool. I have P0171 code (lean condition) that comes on and off. I posted earlier about this, but I fixed a lot of things in the meantime.
What does it mean when fuel trim is too lean?
This process is continuous: when the oxygen sensor detects too much oxygen, the PCM assumes that the air/fuel mixture is lean and adds more fuel. When there is too little oxygen in the exhaust (air/fuel mixture is rich ), the PCM reduces the amount of fuel. In technical language this adjustment is called fuel trim . What is the Fuel Trim?
How does the PCM adjust the long term fuel trim?
In a long term, the engine computer (PCM) will compensate this condition by adjusting the long-term fuel trim (LTFT) to add more fuel. The long-term fuel trim is also displayed as a percentage with a “-” or “+” sign in a scan tool.
How to check long term fuel trim values?
And this can easily be done by checking the Long Term Fuel Trim values (for bank 1 and bank 2) with your scan tool in Live Data mode (Don’t have a scan tool? Need a scan tool? Check out my recommendation: Actron CP9580 Scan Tool ).
https://www.youtube.com/watch?v=RrkPS9s7UBU