AFM Issues P0300 - This may help you

[RAFJR]

Just thought I would share my AFM experience on my 2012 Yukon Denali 6.2l 65,000 miles.
In order, this what occurred and the remedy I pursued. In the end, I shut off the AFM by deleting the command from the ECM.

1. P0300 Code and Oil pressure gauge erratic or non responsive
2. Replaced oil pressure sensor P0300 remained
3. #5 cylinder random misfire
4. Replaced plugs and wires P0300 remained
5. Ran 3 bottles of Techron through the tank P0300 remained
6. Checked battery and ALT - good.
7. Checked all grounds
8. Replaced #5 coil P0300 remained
9. Replaced crankshaft sensor - P0300 remained
10. Discovered P0300 would get thrown when vehicle went into AFM mode
11. Talked to an AFM guru, he said solenoid in VLOM was the culprit and suggested turning off AFM.
12. Sent ECM off to a guy for $50 - he turned AFM off - problem solved. NO P0300 code

 

[Joseph Garcia]

Thank you for sharing this information with us. Our collective knowledge base has been increased.

 

[1BADI5]

Keep an ear out for the lifters though. Turned off in the tune is great, but you still have AFM lifters in there; they can still fail or collapse at anytime.

Not trying to be Debbie Downer.........but it's the reality of the situation.

 

[iamdub]

Just thought I would share my AFM experience on my 2012 Yukon Denali 6.2l 65,000 miles.
In order, this what occurred and the remedy I pursued. In the end, I shut off the AFM by deleting the command from the ECM.

1. P0300 Code and Oil pressure gauge erratic or non responsive
2. Replaced oil pressure sensor P0300 remained
3. #5 cylinder random misfire
4. Replaced plugs and wires P0300 remained
5. Ran 3 bottles of Techron through the tank P0300 remained
6. Checked battery and ALT - good.
7. Checked all grounds
8. Replaced #5 coil P0300 remained
9. Replaced crankshaft sensor - P0300 remained
10. Discovered P0300 would get thrown when vehicle went into AFM mode
11. Talked to an AFM guru, he said solenoid in VLOM was the culprit and suggested turning off AFM.
12. Sent ECM off to a guy for $50 - he turned AFM off - problem solved. NO P0300 code

Sent your PCM to the lt1swap.com guy?

Keep an ear out for the lifters though. Turned off in the tune is great, but you still have AFM lifters in there; they can still fail or collapse at anytime.

Not trying to be Debbie Downer.........but it's the reality of the situation.

Reality, indeed.

@RAFJR, I had my AFM disabled with a tune. This fixed a few minor issues I had and all was well for about two years. Then a lifter started talking shit to me at startup after the Tahoe was parked for a few days. I took this as a warning and deleted the AFM proactively. As Jeremy said, pay attention to the lifters.