Idling rough loss of power fuel consumption

2002 OLDSMOBILE AURORA
200,000 MILES • 4.0L • V8 • 2WD • AUTOMATIC
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CNOTE9192
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  • 1 POST
Idle RPMs are lower than previous , idle is rough, engines rocks badly, fuel consumption , obd2 reader live data shows no long term fuel trim % at all idle or when driven.
Feb 18, 2022 at 10:56 AM
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KASEKENNY
  • CAR REPAIR CONTRIBUTOR
  • 18,907 POSTS
This could be a sensor issue, but long term is a calculation based on a number of inputs including short term, so let's start with what the short term is reading.

I am attaching a chart below that will help with determining if they are rich or lean.

So, I am going to assume we have a lean mixture which would mean a vacuum leak or low fuel pressure issue. So, let's start by checking the short term and if it is lean, use this guide to see if there is a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Once we know this info, we will have a better idea which direction to go.

Thanks
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Feb 19, 2022 at 6:56 AM
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