Hello! Trying to pick your brain on my 2013 Yukon XL with 6.2L. Had the P0304 code with traction control light and stabilitrak lights come on. Engine light flashes. Got the vehicle home, restarted with no lights. Drove it 200 miles lights come back on and stayed on. Has AFM disabled with Black Bear tuner. New spark plugs last year. Plugs look good, coil packs look good, checked injectors last night. One looked a little different so swapped it, but still stayed on cyl 4 when rechecked. Vehicle idols rough after about 45 seconds but does not shut off. Filled up with gas in between light going off and coming back on- use premium. A couple years ago I put regular gas in it to get me home and threw a light. Hubby told me not to do that again! So I only use premium and synthetic oil. I just question if it would be a lifter if the light doesn’t stay on and drove fine in between. If I read correctly the lifter has a pin in it to keep it open with the AFM disabled. So I’m struggling with the thought of it being a collapsed lifter. Anything else I should try before pulling valve cover? Thanks!
2013 Yukon 6.2 with p0304 code
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Joseph Garcia
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Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.
these lifters do still fail even with afm turned off in the tune. not that they release the pins and get stuck, but they will fail in other ways.
do you have any tapping?
do you have a scanner you can see data on? you can also swap a plug with another cyl or replace just the one.
do you have any tapping?
do you have a scanner you can see data on? you can also swap a plug with another cyl or replace just the one.
Yes, I do have access to a scanner. Tonight my husband checked compression on cyl 4. At first it was getting pressure, then a few cycles later it did not, then the last time it had pressure again.
sounds like it's time to pull a valve cover off and watch the rocker while cranking. but if you don't have compression, I'm guessing something has gone wrong with that lifter, even thou you have it turned off. why? I don't know.
if it does stop opening the valve. you could try the short cut the crazed performance guy does, and maybe it's somehow getting oil pressure to the lifter even thou it's off. maybe thru a leaking vlom solenoid. that requires ordering 20$ worth of stuff and removing the intake and vlom, that's pretty easy compared to pulling the heads but it would be a try, the real way is to pull the heads, either replace everything afm related with new oem parts or go with a delete kit, new cam and lifters.
slyhog022056
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I am having the same problem with #4 I am not getting signal from ECU to coil. Pull the plug wire and put a plug in the end of the plug wire and start it and get out to see if you have spark. dont touch the plug or metal get insulated pliers and ground the end of the pkug and see if it is firing.
slyhog022056
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the stabilitrac and traction controls are being shut off by the ecu because of the misfire, they will go away when it runs right again.
Pressureangle
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Possible broken valve spring.
mikez71
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Difference is, they checked compression. Had some, lost it, then had it again.
wjburken
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I just replaced a broken valve spring on my 2013 Denali. Had it towed to a local shop that said they did diagnostics on it and gave me a quote for $5500 to replace the lifters. Told him I’d do it myself and had him tow it to my house. Spent 45 minutes removing the valve covers and found a broken valve spring. Got lucky that there was no damage to the valve or piston and got it back up and running.
mountie
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That is an 'ouch'....... I hope my '05 5.3 doesn't do that..... Or is it on your newer engines?
wjburken
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That is in my 2013 Yukon 6.2. Had the same thing happen on my 2007 Yukon 6.2.
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Update: So i pulled the vlom and tried the plug from cpr to block oil to the lifter. While i had the intake off, jumped the starter relay, and the valve would work first 5-6 strokes and then quit moving. I put in the plug and put it back together and still same thing, misfire in 4. I havent messed with it since, had a vacation last week.
I am now researching a delete, assuming i have a bad lifter. Trying to decide if i want to do a stage 1 while i have it tore apart or go back stock.
I am now researching a delete, assuming i have a bad lifter. Trying to decide if i want to do a stage 1 while i have it tore apart or go back stock.
did you happen to clip the gasket around the holes leading down to the lifters? that vents any oil pressure thst might build up in there and release the lifter.
I did not clip the gasket, if I do and oil does get in there below the vlom is it able to drain back to the oil pan? I blocked oil to the vlom because I feel like after it builds oil pressure is when the lifter collapses but the vlom plug didn’t work. Would have bet money it was a solenoid leaking by to the lifter.
yeah, he's got a video showing clipping the gasket. I did mine, so as I understand it when the vlom solenoids are closed and not supplying oil down the hole to release the lifter, they are vented to allow oil that comes from around the lifter bore to not build up pressure. if that vent becomes plugged up somehow, and the lifter bores get worn. the oil pressure can build up.
no clue if that fixes anything. maybe your lifter lock pins have become worn or something. but thst the theory anyways.
Makes sense to me what you’re saying and what he’s showing. I may give this a shot before buying anything else. Why do the blank valley covers have orings to seal the towers and some suggest plugging as well.
What caused you to do yours, did you do a full delete?
those are for when you replace the afm style lifters with standard lifters. at that point there's no need to vent oil.
I did mine as preventive maintenance. got it at 135k and turned it off in the tune with hptuners on the drive home and did the pressure block and gasket clips as soon as I had time. at 162k now and fingers crossed it makes 300k. I have the hybrid yukon version and there's no delete kit for it. it's a special grind late intake valve closing with higher compression pistons to compensate. I don't believe I can just slide a standard grind cam in it and it run correctly. there's a few posts about guys doing it, but when I ask if it worked no one seems to reply. so I'm taking it as a no. hptuners isn't well defined for the hybrid ecm. has very limited adjustments. I don't believe I have access to what I need to tune for a standard cam.
sadly I don't even know if gm sells this cam anymore. so I figured anything I can do to make it last was worth the small mpg loss. I did consider replacing the lifters and vlom with oem ones but pulling the heads over it seems like a hassle I would like to avoid as long as possible.
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