Hi Matt and thanks for using 2CarPros. Com.
Under perfect conditions, the fuel trims should be near 0. However, what you see is not really out of the ordinary. At idle, when they should really be checked, (STFT), I would like to see it closer to 0, but it isn't that bad. Since it is negative, that indicates to me it is a little rich, nothing bad, and the computer is trying to lean the system. The positive numbers on acceleration tell me the computer is trying to lean the system, which is normal. If your vehicle is running okay and there are no trouble codes stored, I would leave it alone. If it stayed rich (in the negatives) all the time, I would suspect a leaking injector, fuel pressure too high. If it was always in the positives, it is trying to add fuel, so suspect a vacuum leak, low fuel pressure. However, it is not. If you take the average of your readings, there are really close to 0.
I hope this helps. Let me know if you have other questions.
Take care,
Joe
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Friday, November 16th, 2018 AT 8:36 PM