ive had this issue with my LTG where it will start to pull power and sputter till it stalls out sometimes if i blip the throttle it will start to come back . I have been trying to manage to get it on a log for a few months but finnaly managed to today Below is that log if anyone can help me figure out what is causing this it would be much appreciated.
O2 stuck rich - flatlined at 1277mV for the first part, then it wakes up and starts reading what I'd suspect is the actual which is lean (from the trims pulling fuel trying to bring the stuck O2 back down).
how do i fix that would it be tune related or something physical
Not tune related. 1.2something volts is the max the O2 signal pin is capable of reading - if for instance you put 5 volts to it or 12 volts to it, it would still show only 1.2xx.
O2s generally don't fail by internally shorting the signal to voltage, they either go open circuit (in which case you get the default bias voltage of ~450mV and no activity) or short to ground. It's theoretically possible that it could be shorting signal to the heater voltage ckt, but really unlikely. My gut says this will end up being a harness issue, shorted to +12v somewhere along the way.
However... if you don't know for sure that the upstream O2 was replaced recently, then it's always going to be an unknown and might be a good idea to replace it just as maintenance before sinking a bunch of time into it. Use only NTK or Denso (or genuine GM, which will be either NTK or Denso in a blue GM box).
If you can get it to fail while in a controlled environment, the thing to do would be to unplug the front O2 while it's stuck high. If it stays high even when unplugged, it's something in the harness or internal in the ECM. If it drops to ~450mV unplugged and goes back to 1200mV plugged back in it's the sensor. Tricky part is getting access to the connector and unplugging it without wiggling part of the harness where the problem might be - unplugging it could un-short the harness and you could trick yourself into thinking the change was due to the unplugging, not the wiggling.
Does it seem to do this at the same engine temp every time (during warmup, like in that log) or is it random?
The upstream o2 was replaced in January this year and no it is extremely random when it happens i did a hour drive a few days ago and it was fine till i wasent moving. it did it this morning right after cold start and then later in the day while i was on throttle moving down the highway
Well all I can tell you, from 20+ years in GM dealerships, is that it's highly unlikely this is a bad sensor, look for harness problems. The richest rich exhaust that's ever been rich won't make a sensor go over about 970-980mV, you have something putting more than normal O2 signal voltage onto that line somewhere.
good to know but idk jack about wiring or electrical. do you know where i should start
I think you might be better off and come out cheaper in the end to just pay someone competent to fix it for you. Specialized tools, specialized knowledge, access to diagnostic resources... diag on a 2014 anything isn't something you can learn from a few forum posts.
so goodish news i replaced the upstream 02 because it had a warranty on it and it hasn't had any issues in 11 days
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Originally Posted by AdamStuff
