What is 'fuel trim' and what does a large positive long-term fuel trim (LTFT) indicate?
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A
A factory safety setting limiting maximum injector duty cycle to 80%
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B
A correction the ECU applies to fueling; a high positive value means the engine is running lean and adding fuel to compensate
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C
A negative pressure reading indicating a vacuum leak in the exhaust system
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D
A transmission adjustment that enriches fuel during gear changes