P0307 code

Tech discussions on the L77 6.0L V8.
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Grandstaff
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Joined: Mon Mar 13, 2023 10:22 pm

P0307 code

Post by Grandstaff »

The other day while driving my car, I made a left-hand turn, and my car shuddered a bit. Then a service StabiliTrak message came up along with a check engine. Thankfully I have my Bluetooth obd2 scanner always plugged in, so I scanned it, and it read a P0307 code. I limped my car the rest of the way to work. After work, however, while sitting in traffic, I noticed white smoke coming out the back of my car. When I got home, I parked it and swapped coil packs and spark plug wires, but the issue was still a misfire on cylinder 7, so I then changed all my spark plugs because it was getting to be that time anyway, but it still is spitting white smoke out the driver side tailpipe and throwing a p0307 code after clearing it and doing all of this. Could a blown head gasket be causing coolant to get into the cylinder and prevent ignition? Thankfully this is just a project car, so I have another car to drive, but I would really like to determine the cause of this. Car is a 2015 with 97,000 miles.
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Mooseman
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Re: P0307 code

Post by Mooseman »

Head gasket or cracked head. Smell the exhaust. If it smells like coolant, bingo.

You could do a cylinder leakdown test and see if you get air bubbles from the radiator. And if the plug and top of piston looks like it's been washed, that's another sign. A boroscope would also help.
2011 Caprice PPV, former RCMP test vehicle, never put into service
Build Thread: http://www.newcaprice.com/forum/viewtopic.php?t=2419
Grandstaff
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Joined: Mon Mar 13, 2023 10:22 pm

Re: P0307 code

Post by Grandstaff »

Mooseman wrote: Wed Apr 19, 2023 7:27 pm Head gasket or cracked head. Smell the exhaust. If it smells like coolant, bingo.

You could do a cylinder leakdown test and see if you get air bubbles from the radiator. And if the plug and top of piston looks like it's been washed, that's another sign. A boroscope would also help.
The exhaust just smelled like regular old carbon monoxide, no coolant smell or sweet smell, and the car wasn't overheating. I checked the oil and the coolant and no sign of either mixing. If it is just a blown head gasket I'll just fix that when I eventually dod delete it by the end of the summer.
bstoner
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Re: P0307 code

Post by bstoner »

Swap fuel injectors first and see if it stays or follows the fuel injector. I had a misfire from a bad fuel injector.
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Grandstaff
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Re: P0307 code

Post by Grandstaff »

bstoner wrote: Thu Apr 20, 2023 10:14 am Swap fuel injectors first and see if it stays or follows the fuel injector. I had a misfire from a bad fuel injector.
I just swapped fuel injector 5 with the misfiring 7, cleared codes, and still cylinder 7 misfire sadly.
Grandstaff
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Re: P0307 code

Post by Grandstaff »

I just replaced the valve cover gaskets thinking it could be that, and I drove it around the block, but it still is misfiring and producing white smoke. I'll see if I cant borrow a compression tester from my work on saturday and see if the piston ring is blown.
bstoner
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Re: P0307 code

Post by bstoner »

Usually white smoke is a blown head gasket with coolant getting into the combustion chamber. Not good!
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
Sanford
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Re: P0307 code

Post by Sanford »

Pull the valve cover, start the car and see if all of the rocker arms are moving. The second car I bought had a bad cam / lifter and all of the valves would move while cranking, but the minute the engine fired, the one cylinder with the misfire, one rocker would quit moving. The engine also smoked terribly out of that bank. Put a used low mileage DOD cam and lifers and all has been good since.
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