What causes negative long-term fuel trim?
What causes negative long-term fuel trim? A negative long-term fuel trim means that the ECU has to decrease the injector pulse because the car is running rich. The vehicle needs less petrol in the blend. What should bank 1 fuel trim be at 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. What should my long term fuel trim be? Ideally STFT should be close to 0. But it fluctuates as you...