2019+ Silverado/Seirra DFM Misfiring

tmh8ball

OP

February 26, 2026 at 10:13 PM ET

#1

Experienced misfiring issue with my 2020 GMC Sierra 5.3L Elevation. Got a Deep scan and had multiple misfiring issues all at once and roughly four cylinders having the most issues. Searched like a madman on the issue. Heart sunk!

It was either get a $6k-8k AFM delete. Not an option financially for me.

Through YouTube I tried out a chip that would force the engine to stay in 8 cylinder at all times. As soon as I installed a choice brand of Range Technology Plug & Play AFM/DFM Active Fuel Management Disabler for GM Vehicles RA003G (Green).

Problem solve in my case. So far 25,000 miles later still no issue. Hope this helps!!!!

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TheCarGuy

April 2, 2026 at 11:20 PM ET (edited Apr 2 ET)

#2

that's good news and glad that worked for you. In addition to that, if you keep that oil fresh (every 3-5k changes), and maybe even run some seafoam or other top end cleansers from time to time, that will help too long term.

Do you measure the oil on oil changes? Wondering if you have any oil burn.

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tmh8ball

April 3, 2026 at 9:55 AM ET

#3

I do have oil burn maybe a 1/2-1 qt out of the eight but I thought this was normal as every car I’ve owned has always burned some. My issue with misfiring definitely was a mechanical/control system issue. With before diagnosis, misfires showing on 2-4 cylinders bad. Then after chip install forcing 8cyl at all time was a day and night difference.

I’m skeptical on trying anything such as Seafoam or top end cleaners but open to it. Any data or videos on this that deep dives?

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TheCarGuy

April 5, 2026 at 8:14 PM ET

#4

Some have done videos on seafoam and other detergents. I've used it in my old sequoia, timing chain tensioner started to stick, used seafoam in crankcase as prescribed, only ran it for about 50-100 miles at end of oil change, then dumped it, changed oil fresh...timing chain tensioner did get better and stick less.

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