Check engine light is on and misfire on cylinder two

WELLS L

MEMBER
2012 CHEVROLET IMPALA
3.6L
6 CYL
2WD
AUTOMATIC
140,000 MILES

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?

Sunday, July 11th, 2021 AT 9:03 AM

3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

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

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Sunday, July 11th, 2021 AT 5:06 PM

WELLS L

MEMBER
2 POSTS

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?

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Sunday, July 11th, 2021 AT 5:24 PM

ASEMASTER6371

MECHANIC
52,797 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

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Monday, July 12th, 2021 AT 2:56 PM