O2 sensor effecting LTFT
Thread Starter
On The Tree
Joined: Feb 2020
Posts: 180
Likes: 14
O2 sensor effecting LTFT I am having a problem with the O2 Bank 1 sensor 1 cutting the long term fuel trim. The engine is a 02 LQ4 using the stock PCM. I battled this for awhile, because it was severely cutting the power. Did a ton of diagnosing and fixed some other problems, some really good people on here helped me through it. I eventually figured out the O2 was the problem. When I swapped the engine, I replaced the O2s with new Bosch ones not knowing they were not recommend to be used by the people on here. I’ve flopped them, and I’ve replaced them with new ones under warranty.
As soon as I plug the b1s1 in it immediately cuts the fuel in that bank by -15%, when I disconnect it the truck runs fine and doesn’t cut fuel (I know that’s not a fix). 2 new sensors with the same result, I know they aren’t Delcos, but I can’t see how 2 new sensors have the same result. I think the problem is something else.
Wiring issue? PCM “tuning” issue?
Any guidance or help would be greatly appreciated!
As soon as I plug the b1s1 in it immediately cuts the fuel in that bank by -15%, when I disconnect it the truck runs fine and doesn’t cut fuel (I know that’s not a fix). 2 new sensors with the same result, I know they aren’t Delcos, but I can’t see how 2 new sensors have the same result. I think the problem is something else.
Wiring issue? PCM “tuning” issue?
Any guidance or help would be greatly appreciated!
TECH Fanatic
Joined: Jan 2018
Posts: 1,250
Likes: 239
From: Dade City, Fl.
Read all the spark plugs on the #1 bank. I'm wondering if there is an issue other than the O2 system. I'm inclined to think the O2 sensor isn't lying. Do you notice any ignition misses? Any other DTC's? Are the fuel injectors all known good? Maybe swap the injectors to the opposite banks.
You may have an injector that is stuck open dribbling more fuel than is required. Or.. someone could have replaced an injector on that bank with a different rated injector creating drama on that bank. As the guy above mentioned-for diagnosing this issue-swap all 8 injectors side-to-opposite side and see if the problem jumps tp bank 2.
Thread Starter
On The Tree
Joined: Feb 2020
Posts: 180
Likes: 14
Sorry for never replying to your comments Jetech and Kawabuggy.
Digging this back up, life got in the way and I didn’t need the truck aside from hauling something randomly. Well I’ve been running it daily, and while it does work, I hate that I never figured out the O2 problem.
First step will be to flop injectors. It does run very well and strong. My only other problem is, when I fire it up cold it does not stay running without some throttle input. After about 20 seconds or so it will stay running on its own. It does idle very low.
Digging this back up, life got in the way and I didn’t need the truck aside from hauling something randomly. Well I’ve been running it daily, and while it does work, I hate that I never figured out the O2 problem.
First step will be to flop injectors. It does run very well and strong. My only other problem is, when I fire it up cold it does not stay running without some throttle input. After about 20 seconds or so it will stay running on its own. It does idle very low.
