Misfiring, codes P0300 and C0561-77?

Tiny
REDBONE
  • MEMBER
  • 2013 CHEVROLET SONIC
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
I changed the spark plugs and still had the misfire, so I hooked up a scan tool and found that my 5v reference was at 5.01.I also found that my mass air flow average variance was at 2.62. I don't know what that means. II got codes p0300 and c0561-77. I also noticed that only number 1 spark plug was the only one misfire, the other 3 didn't show any misfire. I have rough idle and the engine stutters at 2,700 to 3,000 RPMs and doesn't have much power. Will the 5v reference being high cause these issues and the mass air flow being high.
Wednesday, September 7th, 2022 AT 3:57 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,055 POSTS
Hi,

The MAF variation average is okay. At idle, it should be between 2 to 7 G/S (grams per second). As far as the voltage, 5.01v is also good. That couldn't be any closer to 5.0v.

Now, since the misfire is only on cylinder 1, first remove the coil and inspect the rubber boot that goes on the spark plug for evidence of arcing or oil contamination. See pic 1 Arcing will usually leave a lighter gray spot on the rubber.

If there is nothing evident, remove the spark plug and inspect it. I realize they are new, but I want to know if it is wet or shows any evidence of corrosion or other substance.

There is a chance the ignition coil module is failing. However, if everything appears normal as far as the spark plug condition, the next step would be to check engine compression. If cylinder one is lower than the others, it can cause a misfire.

Let me know what you find.

Take care,

Joe

See pic 1.
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Wednesday, September 7th, 2022 AT 8:18 PM

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