After completing an engine swap, low idle and RPMs misfire over 2,000. Reading high voltage on o2 sensor heaters?

2005 CHRYSLER 300
110 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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COLLINE1121
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The car listed above is a 300C with a 5.7L Hemi. Swapped engine, everything is back in, car running. Experiencing low idle and RPMs breakup over 2,000. Reading high voltage on o2 sensor heaters. Changed o2 sensors, still showing high voltage. Code disappeared, but assuming the high voltage problem still exists. At a complete loss right now, please help! P.S. Service manual says I need to perform a powertrain verification test.
Sep 9, 2022 at 9:17 AM
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STRAILER
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High voltage at the oxygen sensor is your clue, it sounds like you have a fuel injector that is not working correctly. I would remove the spark plugs to see which one looks dark or cleaned off. This will be the cylinder that is having the issue. You said no codes, correct? I would run them anyway to see what comes up, and while the plugs are out recheck them for cracks in the porcelain.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go over this guide and report back.

Sep 10, 2022 at 10:06 AM