Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Long Term FT
The Long Term Fuel Trim (FT) is derived from short term fuel trim value. The Long Term FT is used for long term correction of fuel delivery. A value of 128 counts (0%), indicates that fuel delivery requires no compensation in order to maintain a 14.7:1 air to fuel ratio. A value below 128 counts means that fuel system is too rich and fuel delivery is being reduced. The PCM/ECM is decreasing injector pulse width. A value above 123 counts indicates that a lean condition exists for which PCM/ECM is compensating.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.