p0171 and p0174 on a 2014 sierra 5.3 4x4

wilshire37 · February 2, 2021

So I have an odd situation on my truck. I use a Range technologies device to keep the engine in V-8 mode, I have to remove it and let the computer reset to get my inspection sticker. After doing this I got a CEL with P0171 and P0174( lean condition bank 1 and 2) I cleared the light and drove the truck but it came back on. Plugged the Range device back in and no CEL. The truck runs excellent no misfires, hissing, stumbling, bad gas mileage...nothing. I cleaned the MAF and even installed a new one I had(GM) but light came back on. Checked all connections, lines, gas/oil cap, dipstick fully seated, no exhaust leaks...nada. I 'm leaning towards a possible PCV valve? Any ideas? Thank You in advance.

silveradosid · February 3, 2021

that is a strange one, google gm drive cycle and try that

BigBadSierra · February 3, 2021

There is one bad part to the Range device. When you use then it prevents the AFM from working so the lifters never change their state.

So now they my be stiff and not fully functioning. Try changing the oil and going for good long ride and see if it clears up.

The issue is when they fail the computers keep working as if it's in V4 mode so it may be dumping fuel into the cylinder but not sending the spark so the fuel now blows past the sensors and triggers a Cell.

This may be why it goes back to working normal when the Range is back in. These AFM Lifters either collapse or get stuck in place.

wilshire37 · February 5, 2021

The range keeps it in V-8 mode so all the lifters are working all the time. Non functioning lifters would give running issues which I have none of. These codes are lean codes so I'm figuring unmetered air is entering after the MAF sensor somewhere. My next step I guess would be to have the engine smoked. thanks for the responses.