Cooling and ignition system

[Danny Fowler]

I bought a 2012 Sierra Z71 in Jan '20. Engine code 7 LC9 5.3 with AFM. I've had to replace spark plugs twice because of misfires. I'm using recommended AC Delco iridium plugs. When the 1st set came out, a couple of the plugs were burnt and cracked. 2nd set, plugs 7 and 8 were burnt, 7 had a lot of oil on it. Truck runs at a consistent 210 degrees. Is this too hot? 

[CamGTP]

The cluster will always report 210 because that is how GM does things. The actually temp is normal 190-200ish if you used a scan tool through the OBD2 port to read the temp sensor. That temp is perfectly fine, the newer trucks run at 210-215 all the time without issue.

 

Some engines will burn a lot of oil because of the AFM system and number 7 I see it happen a lot. You can buy a AFM disabler device and it should help with fouling spark plugs and burning oil.