Misfire Cylinder #7 P0307 W/ White Smoke

[wyattkb]

Hey guys was wondering if anyone could shed some light on whats going on. I have a 2015 Silverado 5.3, I went for a drive today and had a loud backfire followed by blinking check engine light and traction control light turned on. Lots of white smoke out the exhaust as well. Pulled the code and it was P0307 and it definitely is misfiring. Truck only has 45k miles on it, I limped it back home and will attempt to pull the plug on #7 tomorrow to diagnose but I can't see it being fouled after 45k miles. Engine has never been overheated and oil pressure is fine as well.

 

Everything I am reading says stuff about ABM failure causing bent pushrods/valves. But I have a AFM turned off.

[CamGTP]

Just because AFM is turned off doesn't stop the fact that all those parts are still installed in the engine.

 

A lifter failure can still happen.

 

Pull the plug and check it out. See if it's covered in stuff. White smoke is typically coolant, so hopefully it's not a head gasket.

[wyattkb]

27 minutes ago, CamGTP said:

Just because AFM is turned off doesn't stop the fact that all those parts are still installed in the engine.

 

A lifter failure can still happen.

 

Pull the plug and check it out. See if it's covered in stuff. White smoke is typically coolant, so hopefully it's not a head gasket.

Pulled the plug and it was quite fouled and had a little oil on it. Swapped it with a brand new plug and still the same issue. I have a dealer appointment scheduled tomorrow AM, hopefully whatever they find is covered. I will report back when I get the report.

 

[wyattkb]

Also when I started it up this morning there was no smoke.

[Cwildman]

I'm definitely interested in what the findings are

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[wyattkb]

Dealer called up and said spark and fuel was good but still misfiring. They are doing a quote "cold start" tomorrow morning to further diagnose. Doesn't seem to be looking good so far.

[ItzBrad]

Hey man i seen your post and read it. I have a 2015 Sierra w/5.3 and 50k miles. The same exact thing happened to me as well. I ended up tearing the motor apart myself and found the exhaust lifter on #7 stuck in the block. Im fixing myself so i can delete all the afm bs.

[wyattkb]

Dealer just called me and said they found dirt and water in the intake which caused cylinder #7 to fail so they will not be honoring the warranty. I am heading down there now to inspect it because that is not possible.

[Cwildman]

Stock intake?

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[wyattkb]

7 minutes ago, Cwildman said:

Stock intake?

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No, Volant intake. Apparently it's terribly designed because it opens to the side and bottom of the fender. Tech showed me inside intake plenum and tube was covered with dirt, 0 compression on cylinder 7 and oil looked like glitter. Looks like I'm SOL. Now I have to pull it apart and see if the block is even salvageable. I will still check #7 lifter but the metal in the oil pretty means the whole engine needs to be torn down

[Cwildman]

I would contact volant, take pictures and see what they have to say about the whole thing. I know they won't do anything about it but curious to know what they would say

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[wyattkb]

3 hours ago, Cwildman said:

I would contact volant, take pictures and see what they have to say about the whole thing. I know they won't do anything about it but curious to know what they would say

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Honestly it might be a 50/50 thing, bad design and the fact I have widebody fenders the fender liners are no longer there. Easy way for water/dirt. Plus I bought the vehicle used and only put on 3000 miles so their is the chance the previous owner had an issue and sold it to me. Either way I am going to suck it up and pull the engine this weekend. I'll document what I find for the community.

[wyattkb]

Got started with pulling the motor out today. Pulled the valve cover off to check the function of the lifter, sure enough its frozen in place. I will probably just continue pulling the engine the rest of the way out. Going to drain the oil and cut open the oil filter to inspect for any metal shavings inside.

 

Since its this far apart already (whole front end taken off) I will pull the engine and further inspect everything. 

 

TL:DR Dirt in the intake did not cause this failure, it was the AFM/DOD. Stuck lifter. Screw dealerships, but I will bite the bullet and eat this one since I or the previous owner let dirt get sucked inside the intake without inspecting that first.

 

Video of what it looks like. https://imgur.com/CpHM4gq

[Cwildman]

Hey thanks for the video, seeing as I am seeing/reading about a ton of these lifter issues on the L83 I will be reading more about it. Itd be cool if you could keep this thread updated with your progress. Where are you getting parts? I know gpi offers kits.

I'd like to know more about deleting afm. I have mine turned off but know this stop lifter failure.

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[wyattkb]

8 hours ago, Cwildman said:

Hey thanks for the video, seeing as I am seeing/reading about a ton of these lifter issues on the L83 I will be reading more about it. Itd be cool if you could keep this thread updated with your progress. Where are you getting parts? I know gpi offers kits.

I'd like to know more about deleting afm. I have mine turned off but know this stop lifter failure.

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I haven't decided if we are going to rebuild the 5.3 or just swap in a 6.2. Either way I will be getting the AFM delete from texas speed along with a cam kit for either motor I go with. Note I did have the AFM deactivated and the previous owner deactivated it at like 3,000 miles and it still failed. I will document as much as possible, not much info around on people doing this swap and the service manual is $600. It seems the hardest part is going to be finding a tuner that can get everything working.