#7 Cylinder Misfire

[greyjimmy]

On 3/21/2017 at 7:02 PM, T-Town-Z said:

I'd be curious to know if these AFM components fail just randomly, or if there is something that may aggravate it ? Like if those who run their trucks hard, or pull loaded trailers ??? I know I don't "baby" mine, but I don't really abuse it either.

Thats a good question.  My 2015 Sierra with 62000 miles just went into limp mode and the engine definitely sounds like a lifter is sticking.  I towed it to the dealership, we'll see what they have to say.

[Loco-diablo]

9 hours ago, greyjimmy said:

Thats a good question.  My 2015 Sierra with 62000 miles just went into limp mode and the engine definitely sounds like a lifter is sticking.  I towed it to the dealership, we'll see what they have to say.

The 2015's have a 100K powertrain warranty, yes?

[greyjimmy]

Yes thank goodness.

[greyjimmy]

I heard from the dealership today.

To recap, My 2015 Sierra 5.3 just had the same thing happen.  62,000 miles.  It occurred as I was merging into traffic from a stop to at about 25 mph.  It suddenly stuttered then check engine light came on and the traction control light on the dash.  I pulled over and could hear the lifter knocking.  It threw a P0300 and P0307 code.  I had it towed to the dealer, it's lifter #7.   It will be covered by warranty.  They will replace the lifters on that bank but not the other side.  I will have to pay for that myself.  They are going to check the camshaft for pitting as well.

I've only had the truck for 6 weeks so I don't know it's history as I bought it from the dealer andmost of it's service was done elsewhere.

I'll post the progress.

Edited May 10, 2018 by greyjimmy

[greyjimmy]

Dealership did as they said they would do and the truck is back to normal.  Covered by warranty and turned around in three days.  Runs like a top again.  

[greyjimmy]

On 3/21/2017 at 3:16 PM, newdude said:

 

 

I wish I had one of these trucks to test that myself. I do recall GM having some mention of oil aeration in their AFM lifter bulletin for these engines.

 

To me...that says 0w20 and maybe those fancy dual stage pumps gets the oil worked up and aerates it, thus causing the pins in the lifters to fail.

 

On the AFM lifters on the OHV engines, the VLOM solenoids send oil pressure (oil) to the lifters and they force the locking pins closed. When the solenoids close, they pull oil away from the lifters and the pins lock and you have all 8 cylinders.

 

Lets say you disable AFM. Now, you have no chance to send that oil pressure to the AFM lifters to unlock the pins. You've just eliminated a chance for aerated oil to unlock the lifter, and then due to its aeration, suddenly lock the pin while its supposed to be keeping the valves closed, it pushes the valve, whacks the piston and bends the rod and the AFM lifter fails.

 

Its definitely a theory that I wish I could test. On the other hand, on my 2012 1500 5.3, I never disabled AFM, and it saw some strong RPMs quite a bit sometimes, and had zero oil consumption and no AFM lifter issues.

Thank you for the info.  I hope more will post there regarding their lifter issues.  I am curious as to whether muliple lifters go out or if it tends to be #7 and thats it.   Ive got 34,000 miles on my warranty so I hope the others fail now if they are going to at all.

[Beer Belly]

Here is the explanation as written by the Tech on my truck....GM would not authorize any repair.....32k on the truck. Had real bad misfire and check engine and traction control lights on, and of course as I approached the dealership, all went back to normal...

 

Scanned for codes and found PO300 passed. Check misfire data and found misfires in cylinders 1,3,5 and 7. 6900 misfires in cylinder 7. test drove and was unable to to duplicate misfires.Performed cold start test per PIP5498G and found slight slight misfires in multiple cylinders including cylinder 4 but nothing like what the guest experienced. Removed spark plugs and found no obvious issue with the plugs. Installed wire and plug and soaked in warm soap water and ran vehicle. No misfires. Called TAC opened case *-********* due to not having PO50D do not believe it is fuel injector. Instructed to duplicate to proceed"

[Glen Kierstead]

Had this same thing happen to my 2014 5.3 LT Z71 with less than 37k miles on it. Happened to me yesterday. CEL Flashing with the Stabiltrak light solid. Start ticking even while pressing the gas. Rough idle and just running and sounding like dog crap! Called and scheduled a service appointment on it today for tomorrow at 7am. My code reader just showed P0300. Will update on what I find out over the next few days. Really disappointing tho. Almost want to just fix it and then sell it!!!

[Beer Belly]

20 hours ago, Glen Kierstead said:

 Almost want to just fix it and then sell it!!!

Mine is a Lease......I would like to buy it out, not sure what to do now. Dealer said they would "Go to bat for me if it happened outside of Warranty". My past experience is that this would not be covered under the Driveline Warranty. What bothers me is the Techs notes.....6900 mis-fires from cyl. 7 ?......slight mis-fires from multiple cyliders performing test ?....no repair authorized ?

 

"6900 misfires in cylinder 7. test drove and was unable to to duplicate misfires.Performed cold start test per PIP5498G and found slight slight misfires in multiple cylinders including cylinder 4 but nothing like what the guest experienced." 

[cpttimerestraint]

I too am having misfires on 7 on my 2014 5.3. Mostly at cold start. Have it at a private mechanic who is testing a lot of d different things. Pip5498 is if you are getting coolant in the cylinder. Could still be a clogged injector. Mechanic said that there is a lot of carbon in my cylinders. He can see black rings around the injectors. He said to definitely regularly use techron in the fuel.

He did multiple compression tests at different temperatures and it is holding.


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[cpttimerestraint]

Now that the cylinder is clean, they are seeing a lot of oil and coolant in it. I took it over to the dealer and we will see what that say. Thinking I might be part of pip5498.

 

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[cpttimerestraint]

Just got word that they are replacing the driver's side head and injectors under warranty. Simi Buick GMC gives top notch service. If you are in the Los Angeles area, check them out.

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[Csjumper2003]

I’ve now seen that rather afm is off or on, this can happen.  My truck is at 39000 miles 15 Sierra 5.3 ltr. and left me on the side of the road.  Ticking noise coming out and P0307 is what my scanner showed.  I had never seen a check engine light just blink so it through me off.  Then limp mode getting into traffic.  Yeah that’s no good for anyone.  Dropped off at dealership on Friday after closing and waiting for a call.  I called them on Monday to find out something but all they would say is he needs to go talk to mechanic to see what he came up with.  He was supposed to call me back at the end of the day and did not.  So now just waiting for the words.  Not sure the exact cause yet.  

 

[Csjumper2003]

So just heard back from dealership. So I have a water pump leak and they are pulling the head with a suspected lifter failure.


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[faulknej]

On ‎5‎/‎30‎/‎2018 at 6:57 PM, cpttimerestraint said:

Just got word that they are replacing the driver's side head and injectors under warranty. Simi Buick GMC gives top notch service. If you are in the Los Angeles area, check them out.

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How many miles on it when this happened?