2012 Tahoe 5.3 tap/misfire

[shafner79]

Hello,

2012 Tahoe LS 5.3 w/ 217,000

First post. One of my best friends passed and I bought his 2012 Tahoe LS. It sat from June to December untill I could actually purchase it due to estate issues. I started and ran it every week while it sat. I even drove it a few times in June.

I dropped it off New Year's Eve to get inspected. I picked it up on January 2nd. It was running fine and then randomly started tapping. (After research it sounds like the normal driver side lifter tap). The CEL started flashing (P0351,P0301and P219A) and the traction/stabilitrack lights were on. I shut it down and checked the fluids. The fuel light had just came on as I was driving back from the mechanic shop . All fluid levels were good, although the oil needed changed. I added some Marvel Mystery Oil, ran it for a few minutes, shut it off and then cleared the CEL. Started it back up and it is quiet has not tapped since but it's still missing. The weird thing is that when I clear the code while it's running, the engine clearly changes sound.

I have changed all 8 plugs to AC Delco and AC Delco wires. Changed the oil with Valvoline Full Synthetic High Mileage and added Liqui Moly engine treatment.

It starts and runs pretty smoothly now. Although you can feel the abnormal idle while sitting in it. At idle the CEL is not on until you increase the rpm. Then it shows the same code. If you put a load on it it clearly misses. The CEL is showing only P0301 now.

I'm so lost and defeated. It was running and driving fine since day one and as soon as it got inspected this happens .....

Any suggestions would be appreciated. I have pretty decent skill and knowledge when it comes to vehicles. No official training but I have done pretty much everything but change a motor or transmission.

Thanks,
Matt

 

[Geotrash]

Hello,

2012 Tahoe LS 5.3 w/ 217,000

First post. One of my best friends passed and I bought his 2012 Tahoe LS. It sat from June to December untill I could actually purchase it due to estate issues. I started and ran it every week while it sat. I even drove it a few times in June.

I dropped it off New Year's Eve to get inspected. I picked it up on January 2nd. It was running fine and then randomly started tapping. (After research it sounds like the normal driver side lifter tap). The CEL started flashing (P0351,P0301and P219A) and the traction/stabilitrack lights were on. I shut it down and checked the fluids. The fuel light had just came on as I was driving back from the mechanic shop . All fluid levels were good, although the oil needed changed. I added some Marvel Mystery Oil, ran it for a few minutes, shut it off and then cleared the CEL. Started it back up and it is quiet has not tapped since but it's still missing. The weird thing is that when I clear the code while it's running, the engine clearly changes sound.

I have changed all 8 plugs to AC Delco and AC Delco wires. Changed the oil with Valvoline Full Synthetic High Mileage and added Liqui Moly engine treatment.

It starts and runs pretty smoothly now. Although you can feel the abnormal idle while sitting in it. At idle the CEL is not on until you increase the rpm. Then it shows the same code. If you put a load on it it clearly misses. The CEL is showing only P0301 now.

I'm so lost and defeated. It was running and driving fine since day one and as soon as it got inspected this happens .....

Any suggestions would be appreciated. I have pretty decent skill and knowledge when it comes to vehicles. No official training but I have done pretty much everything but change a motor or transmission.

Thanks,
Matt

Sorry to hear about your loss of a close friend. :-(

If there is no longer any mechanical tapping/rapping noises, then I suspect the following possibilities, in order:

1/ A bad replacement spark plug. Where did you source them from? Lots of counterfeit Delco plugs out there on sites like Scamazon and Evilbay.
2/ A spark plug wire not fully seated either on the plug or in the coil.
3/ A damaged/bad coil
4/ A broken wire in the harness to either the #1 coil or the #1 injector.

 

[Joseph Garcia]

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.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[solli5pack]

P0301 means you have a misfire on cyl 1 and someone will need to troubleshoot what's causing it. Tons of info on these fourms and YouTube on how to do that. Could be anything from a bad lifter to a bad plug wire so definitely recommend to take time and do research rather than fire parts at it.

 

[Foggy]

Exactly what Geotrash says above...
Prob a coil pack is my guess too

 

[shafner79]

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.

You are already receiving sage advice from the knowledgeable folks on this Forum.

 

[RET423]

It sounds like a faiiling/sticking AFM/DOD lifter on the number one cylinder, the tap goes away when the plunger manages to snap past the dogs but it is not fully extended so it misses slightly at idle; once the RPM is increased the miss is pronounced enough for the computer to narrow down the affected cylinder and it throws the code.

 

[swathdiver]

Hello,

2012 Tahoe LS 5.3 w/ 217,000

First post. One of my best friends passed and I bought his 2012 Tahoe LS. It sat from June to December untill I could actually purchase it due to estate issues. I started and ran it every week while it sat. I even drove it a few times in June.

I dropped it off New Year's Eve to get inspected. I picked it up on January 2nd. It was running fine and then randomly started tapping. (After research it sounds like the normal driver side lifter tap). The CEL started flashing (P0351,P0301and P219A) and the traction/stabilitrack lights were on. I shut it down and checked the fluids. The fuel light had just came on as I was driving back from the mechanic shop . All fluid levels were good, although the oil needed changed. I added some Marvel Mystery Oil, ran it for a few minutes, shut it off and then cleared the CEL. Started it back up and it is quiet has not tapped since but it's still missing. The weird thing is that when I clear the code while it's running, the engine clearly changes sound.

I have changed all 8 plugs to AC Delco and AC Delco wires. Changed the oil with Valvoline Full Synthetic High Mileage and added Liqui Moly engine treatment.

It starts and runs pretty smoothly now. Although you can feel the abnormal idle while sitting in it. At idle the CEL is not on until you increase the rpm. Then it shows the same code. If you put a load on it it clearly misses. The CEL is showing only P0301 now.

I'm so lost and defeated. It was running and driving fine since day one and as soon as it got inspected this happens .....

Any suggestions would be appreciated. I have pretty decent skill and knowledge when it comes to vehicles. No official training but I have done pretty much everything but change a motor or transmission.

Thanks,
Matt

Matt,

You have a leak of some kind and maybe a bag ignition coil on the #1 cylinder. Check the plug and wire first, check the induction system for leaks, being loose, etc.

The engine oil additive is not going to play nice with the VVT system so stick with regular oil once you get this sorted.

AllDataDIY is your friend here to help you solve these codes. First solve the P0351 and then the 301 will go away and then you can get after the 219A.

None of those codes allude to an internal engine problem.

 

[shafner79]

So we dug a little deeper today....with the valve cover off. The #1 rocker is not moving. The hits keep coming. My son crashed our other SUV last week and totalled it.

Any idea on what I need to do to repair it? New motor or is it fixable?

 

[mikez71]

Have seen some mention of tapping the lifter to unstick it, but it is not a guaranteed thing. I believe someone makes a special tool as well..

https://bobistheoilguy.com/forums/threads/unlocking-a-collapsed-afm-lifter.347468/

Either way you want (Need at this point?) to disable the AFM system! (or full delete)

 

[solli5pack]

So we dug a little deeper today....with the valve cover off. The #1 rocker is not moving. The hits keep coming. My son crashed our other SUV last week and totalled it.

Any idea on what I need to do to repair it? New motor or is it fixable?

It's very fixable. I physically deleted the AFM system in my driveway.

 

[Dustin Jackson]

@shafner79 That's a common problem with this platform. Moving forward there are a few options in navigating the situation depending on your goals. The proper fix would be to open the top of the motor up and remove the parts of the AFM system and put the motor back together using non AFM parts. It sounds daunting but at this point there should be no critical damage that has been done so getting it back on the road should be very straight forward.

You could attempt to remedy the problem but unsticking the problem part but if the problem happened once, it is bound to happen again.

 

[shafner79]

I have it at in an auto electric shop right now. He is going to try to free it up. He also recommended doing the delete. Which I will be doing as long as the motor is okay.
Hopefully I have some more info tomorrow or the next day on what else he found out.

 

[Dustin Jackson]

@shafner79 That sounds like a good plan. You won’t know the extent of the situation until you open the motor but if you can bide time until it’s more convenient I can respect that.

 

[Geotrash]

So we dug a little deeper today....with the valve cover off. The #1 rocker is not moving. The hits keep coming. My son crashed our other SUV last week and totalled it.

Any idea on what I need to do to repair it? New motor or is it fixable?

Shit, man! I hope your son is okay.

 

[shafner79]

Shit, man! I hope your son is okay.

Thanks! Yes he and his friend were fine.

 

[shafner79]

I found a shop that will do an AFM delete and replace all the parts with non AFM parts. He's going to do the heads and put head gaskets on it as well as the lifters and cam. Then I have a friend with the HP tuner who will reprogram it for me. Looks like it's going to be over $4,000.

 

[Geotrash]

I found a shop that will do an AFM delete and replace all the parts with non AFM parts. He's going to do the heads and put head gaskets on it as well as the lifters and cam. Then I have a friend with the HP tuner who will reprogram it for me. Looks like it's going to be over $4,000.

That's a fair price but keep in mind that you'll need to have it tuned before it's started for the first time without the AFM components. You may want to have him grab the current tune files off it now before it goes under the knife, so he can make the changes and flash the ECU while it's still in the shop.

 

[West 1]

Once they stick with AFM enabled you can free it up but it will stick again unless you disable the AFM system before you run it again after freeing up the lifter. You have to pull off the intake manifold as part of freeing it up. I have done a couple engines with your exact issue, I used the tool to pop it free or unlock the lifter. Then I deleted the AFM system so it will not be activated again which will keep it functioning normally as an 8 cylinder. This can be fixed for reasonable money. The correct fix is to remove both cylinder heads and install all new lifters and while the heads are off do a valve job. It is up to you how you fix it. Most shops are afraid to remove the heads so they all tell you to get a new engine. There is a shop in Texas that supplies the tool and parts to release the lifter and delete the AFM. You can find it on Youtube. After this is done the AFM needs to be turned off inside your computer. There are usually local guys that will do that for $100. Inside the GM computer there is an On Off switch for AFM, it asks, does this vehicle have AFM, and they change the answer to No. From that point forward AFM is no longer active and the car runs perfectly as a normal 8 cylinder engine. Converting the AFM VLOM to non AFM is simple but for $50 you can buy a non AFM manifold off amazon and use it. Shops will not do this type work but for a guy that works in his garage it is an easy fix compared to pulling the heads off.

Video showing how to release the stuck lifter.

 

[RogerK]

Sorry to hear about your loss of a close friend. :-(

If there is no longer any mechanical tapping/rapping noises, then I suspect the following possibilities, in order:

1/ A bad replacement spark plug. Where did you source them from? Lots of counterfeit Delco plugs out there on sites like Scamazon and Evilbay.
2/ A spark plug wire not fully seated either on the plug or in the coil.
3/ A damaged/bad coil
4/ A broken wire in the harness to either the #1 coil or the #1 injector.

I had same symptemes and codes. Mine was one of the 4 elongated lifters failed. Replaced engine, Machine shop rebuild would have been cheaper. Mine from GM guaranteed 36K or 3 yrs.