What should my short-term fuel trim be?
So what should fuel trim values be? Assuming that the engine is in excellent mechanical condition, and that all sensors implicated in metering both intake air and fuel, short-term fuel trim values should generally be between positive 10%, and negative 10% when the engine is running at a steady speed.
How to check fuel trim in GM p0171?
1. With engine at operating temperature, use a scan tool to check and record Long Term & Short Term fuel trims. 2. Shut off the engine. Then disconnect the foul air tube from the intake manifold as shown. Plug both sides 3. Start the engine and check Short Term & Long Term fuel trims.
What’s the problem with the Buick Enclave p0171?
Buick Enclave 2012-2018 3.6 LLT, 3.6LFY engines GM has determined that a vacuum leak in the foul air tube, intake manifold or purge valve may be causing the P0171, P0174 condition. 1. With engine at operating temperature, use a scan tool to check and record Long Term & Short Term fuel trims. 2. Shut off the engine.
What does it mean when fuel trim value is positive?
If the displayed fuel trim value is a positive number, it means that the ECU is increasing the injector pulse width to add fuel to the air/fuel mixture to enrich the mixture because the input data it is receiving tells it that the mixture is too lean.
When to use short term and long term fuel trims?
If you connect a scan tool to such a vehicle, both the short and long-term fuel trim data will be displayed as percentages. Ideally, both values should be at, or close to 0%, when the engine is running at a steady speed, such as when it is idling.
1. With engine at operating temperature, use a scan tool to check and record Long Term & Short Term fuel trims. 2. Shut off the engine. Then disconnect the foul air tube from the intake manifold as shown. Plug both sides 3. Start the engine and check Short Term & Long Term fuel trims.
What does trouble code p0171 mean on Ford 4.6L?
Since the trouble codes indicate a lean condition (P0171 and P0174) on both banks of cylinders, both Long Term Fuel Trim 1 and 2 should be in their maximum positive number range as the PCM adds fuel to compensate for the perceived vacuum leak or failing sensor (whichever it may be). This is what you need to do:
What does a positive number on fuel trim mean?
A positive number tells you it’s adding fuel. Since the trouble codes indicate a lean condition (P0171 and P0174) on both banks of cylinders, both Long Term Fuel Trim 1 and 2 should be in their maximum positive number range as the PCM adds fuel to compensate for the perceived vacuum leak or failing sensor (whichever it may be).
Buick Enclave 2012-2018 3.6 LLT, 3.6LFY engines GM has determined that a vacuum leak in the foul air tube, intake manifold or purge valve may be causing the P0171, P0174 condition. 1. With engine at operating temperature, use a scan tool to check and record Long Term & Short Term fuel trims. 2. Shut off the engine.