Check engine light is on and misfire on cylinder two

2012 CHEVROLET IMPALA
140,000 MILES • 3.6L • 6 CYL • 2WD • AUTOMATIC
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WELLS L
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  • 2 POSTS
Car does not smoke or use oil. Car runs great above 1,000 RPMs. Have misfire on cylinder 2 below 1,000 RPMs. Check engine light is on. I have replaced plugs and coils. Replaced fuel injector for cylinder 2. What could be my problem?
Jul 11, 2021 at 9:03 AM
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ASEMASTER6371
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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Good evening,

I would service the throttle body. If there is carbon build-up, it will block the passages for air to pass into the engine

https://www.2carpros.com/articles/how-a-throttle-body-works

https://www.2carpros.com/articles/throttle-actuator-service

I attached a guide for you for the procedure.

Roy
Jul 11, 2021 at 5:06 PM
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WELLS L
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I have put seafoam through the throttle body vacuum line . There is no carbon on valves and throttle body is clean. I am sorry I didn’t mention that before. Is there anything else I can try?
Jul 11, 2021 at 5:24 PM
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ASEMASTER6371
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 52,796 POSTS
This could be a vacuum leak. Look around the intake for any hoses that may be cracked or off. If you have a leak, it will run poorly at idle.

If you have a scan tool, check the long-term trim readings to see what the percentage is at idle. It should be close to 0 on the monitor.

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Roy

Jul 12, 2021 at 2:56 PM