Poor fuel mileage and sputtering start

2007 NISSAN MURANO
170,000 MILES • 4.2L • 6 CYL • 2WD • AUTOMATIC
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JARED DEROCHE
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I have replaced everything from the PVC valve, O2 sensors, spark plugs and boots, fuel pump, throttle body and sensor and I am still having poor mileage. It also doesn’t accelerate readily, it’s very sluggish and has recently started to sputter when starting. I have poured money and time into this vehicle and I’m not sure which direction to turn. Please help
Apr 12, 2022 at 4:17 PM
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STRAILER
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Hello Jared,

It sounds like you have a clogged catalytic converter. To be sure let's test the unit by following this guide, also does it have a check engine light on?

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

and

https://www.2carpros.com/articles/engine-has-low-power-output

When you say throttle body and sensor do you mean the MAF sensor? I have shown its location in the diagrams below, this can cause the issue as well. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

Image (Click to enlarge)
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Apr 13, 2022 at 5:03 PM
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JARED DEROCHE
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Yes, it was the MAF sensor that I changed. I don’t have a thermometer or vacuum gauge to perform the tests. I will upload a video ASAP of the issues I am having though.
Apr 13, 2022 at 5:16 PM
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STRAILER
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That would help us see what's going on. thank you
Apr 13, 2022 at 5:29 PM