Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
2008 GMC Savana 4.8 - so I'm having trouble with high long-term fuel trims on both Banks a little bit more so on bank one then Bank too but pretty equal for the most part. The fuel trim seem nearly perfect at idle the long-terms do hover around 3.9% or so but as soon as you accelerate they jump up to around 10% literally at any rpm. The photo of the fuel trims is at a steady 2200 RPMs. However I'm a little confused because the other two photos are of the O2 sensors and the voltage is pretty steady high for the most part but dips down lean very quickly. It's confusing because the fuel trims are showing lean but O2 sensors are showing Rich unless I'm misunderstanding something. I don't believe these O2 sensors are working properly. But I bought brand new ones and they look similar to these which are the factory ones. So I'm not sure if I'm having a O2 sensor issue fuel delivery issue or possibly mass air flow I don't have a lot of money to spend right now just trying to figure out where I should start. Any information will be helpful thank you.
LTFT is only part of the picture. You need to consider STFT at the same moment to determine total trim. Plus or minus 10 is perfectly acceptable.
If there is is no code or no symptoms, I would not over analyze this.
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