2008 tahoe K1500. Throwing P0300(random misfire) and P0174 (lean bank 2).

[User_Name]

normally I'd look at long term trims left and right % and short term left and right %. + should be adding fuel, - is removing fuel. get an idea if the computer thinks it's rich or lean. doesn't really mean that's what it's physical doing. just what the computer thinks. like a vac leak it will need to add fuel, but a miss fire can show up in a few different ways, as rich so it's removing fuel, but also the o2 sensor only reads the amount of air in the exhaust. if unburnt fuel of a miss fire is happening, since the sensor doesn't see the fuel, it only sees the extra o2 from it not burning with the fuel. so it's a bit of a process and sometimes hard to tell not being in person where you can check plugs and other physical signs of what's going on.

also I'd look at both o2 sensor voltage, see if they are swinging back and forth pretty evenly. but with the sensors being wired differently from stock, like 2 on one bank. it kinda makes it. even harder to figure out what's going on.
I'd be seeing if you can't figure out what o2 sensor they have where. should be 4. bank 1. front and rear. bank 2, front and rear. you only needs the fronts, but for it all to work right you kinda need both front sensors to be reading the exhaust of the correct side.

I just want to follow up, incase someone in the future runs into something similar.

So after taking it to a few different places, I decided to have two bungs welded on the drivers side exhaust, and installed the O2 sensors that were hanging. Everything goes back to normal. It only costed me about 100$ to have the bungs welded on. I guess the engine was ignoring the hanging O2s somehow for so long. And when the throttle was reset, it probably tried reading the O2s again.

Hallelujah.

So far, 30 min of driving and I haven't felt a single miss. No extreme gas smell. Shifts are normal.

I wouldn't have been able to get this thing back on the road without all the help from you guys. Many thanks.

 

[Geotrash]

I just want to follow up, incase someone in the future runs into something similar.

So after taking it to a few different places, I decided to have two bungs welded on the drivers side exhaust, and installed the O2 sensors that were hanging. Everything goes back to normal. It only costed me about 100$ to have the bungs welded on. I guess the engine was ignoring the hanging O2s somehow for so long. And when the throttle was reset, it probably tried reading the O2s again.

Hallelujah.

So far, 30 min of driving and I haven't felt a single miss. No extreme gas smell. Shifts are normal.

I wouldn't have been able to get this thing back on the road without all the help from you guys. Many thanks.

Awesome! Thanks for following up!

 

[j91z28d1]

I just want to follow up, incase someone in the future runs into something similar.

So after taking it to a few different places, I decided to have two bungs welded on the drivers side exhaust, and installed the O2 sensors that were hanging. Everything goes back to normal. It only costed me about 100$ to have the bungs welded on. I guess the engine was ignoring the hanging O2s somehow for so long. And when the throttle was reset, it probably tried reading the O2s again.

Hallelujah.

So far, 30 min of driving and I haven't felt a single miss. No extreme gas smell. Shifts are normal.

I wouldn't have been able to get this thing back on the road without all the help from you guys. Many thanks.

that's awesome to hear.. I have no clue why anyone would do what they did to the o2 sensors.. but really glad you fixed it.