check my thinking.....

[0rion]

Worked on the neighbor's car next door. Elderly couple in their 70's. They have a 98 Lumina that I did plugs and wires on 8 years ago but in that time they've only put 30k on the car. It was misfiring when their son borrowed it last week so they wanted me to do the plugs again. He did the fuel filter then for them.....I haven't talked to him yet to see what made him do the filter and not the plugs. Pulled the plugs and 4 out of 6 were white like the car was really lean. I swapped the plugs, cleaned the MAF for them, and took a quick log. LT trims were at -16% but short trims were at -1%. It either looks to me like they had a dirty MAF and cleaning it is bringing the trims back in line or they have a false rich condition at certain loads going on. The only thing I can think of that would cause that false rich is an O2 that's drifted. No codes on the car currently and none in the immediate past that they knew of. Car has 115k on it so the O2 is past due. It's a $30 sensor so I may just tell them to do it. I may let them put a few miles on it and take another log and see where the trims are. Any ideas on what you guys would do? I'm just kinda dreading this O2 swap because I bet that bitch is rusted in there tight. I don't want to get into a situation where I'm putting a whole damn exhaust on it for them to swap out a $30 sensor. I will if I have too but that's a worse case scenario. I have a ton of shit to do here on my own vehicles over the next couple of weeks plus help my buddy do injectors on his duramax.

[cammed goat]

If it were me doing the work, I would GENTLY try to loosen the O2s. If they loosen easily, go for it. If not, give your neighbors the heads-up and see what they say.

[GTP231]

Those N/A 3800s are prone to intake gasket and manifold leaks. May want to check that if the long term isn't coming back

[0rion]

it's a 3100

[GTP231]

Thought it said 3.8 in the post oops
Those are even worse about intake gasket leaks

[0rion]

It actually looked pretty clean under the hood. They're pretty gentle on it being 178 years old It's a 98 with 115k miles so it hasn't been driven a ton really. I'm going to let them put some miles on it and relog it and see what the trims say. If they're still wacked out I'll swap out that O2 and go from there.

[RONS98TA]

I would spray a lil rust buster on the o2 now, so if you do need to swap it out, it will have a chance to get into the rust and hopefully make the job a breeze.