Hey everyone, Hope someone can give me a better idea.
|Short version| >read codes and symptoms<

I've read through so much posts about the problems that might be it but can't really find the issue. The car is a hand me down from my wife, it has 95k as of today. Tons of issues when I had got it, let's start with what was replace.

All suspension/brakes/rotors/tires. alignment
Front ABS sensors/wheel bearings
Spark plugs, Fuel filter, Starter, Muffler, Air filters
MAF (twice) unplug trick to reset it also
Trans/brake fluid flush, Oil changes

All this was done within the start of this year. Here's the problem codes that comes and goes by order I've seen it and gone.

P0430 Catalyst System Efficiency Below Threshold Bank 2 (off)
P0134 O2 Sensor Circuit No Activity Detected Bank 1 Sensor 1 (off)
p0171 Fuel Injection System Too Lean Bank 1 (currently pending)

The car been sitting 1 month without starting the car, the codes all disappear but the symptoms are still there.

Symptoms of the car currently:
Cold start car runs fine
Warm/hot the cars start to have rough idle, drop down to 500-600 rpm
Flooring the gas would blog the car down or give out tons of black smoke
1-2 weeks after clean my car I'll see tons of black debris on the rear

I'm leaning toward the Bank 1 sensor 1 and Bank 2 sensor 2 as my next replacement. If that doesn't work the next is the precat and Y pipe. I've dump way too much money into this car and it's too late to turn back now. Inspection is due 11/15 and I've recently have a baby girl so money is getting tighter so I hope someone can me a idea what it really could be.

Thank you for reading and thoughtful answer.

 

The P0134 is probably causing the P0171. A sensor 1 is very important to the operation of the fuel injectors. The sensor 1 is used by the ECU to determine how much fuel to inject into the cylinders. So yeah, replace that O2 sensor.

The P0430 could be the pre-cat plugging up, but it could also be a bad sensor 2. Being a Cali car, the bank 2 pre-cat is fairly easy to remove. Take it off and remove all the catalyst material inside it and make it an empty tube. That will take care of the P0430.

 

It's a low mileage 3.0L, there's nothing wrong with the cats other than maybe not being efficient. He doesn't need to gut them.

 

Maybe maybe not. But he had to get rid of the code. He can try replacing the down stream sensor or put an anti-fouler on it and then go from there.

 

If you have no way of checking the operation of the O2 sensors, as stated above,
I would replace the O2 sensor 1-bank 1, and the down-stream O2 sensor
bank 2. If the P0430 is still on, then go to the plug 2 non-foulers on bank 2
to get relief.

 

One thing for me to know for sure it's bad is when I floor it, tons of black smoke comes from behind. So today I took it to the shop and had them install the 2 O2 sensors I mention. Got it back and FLOOR it and tons of black smoke still came up, wasn't sure is it because of all the build up from the last 4 months or what. I'll see how things go by the weekend and see if it gets better.

Thanks the info guys, much appreciated.

 

Makes sense..been running rich due to bad O2 sensor. Unfortunately, this helps to burn out the precat so that P0430 code is related to it.

 

Alright Guys, seems like it's good news for me. Decided to take my car to get inspected and it PASS! No need to worry about inspection for another 2 years, Seems like 1 or 2 bad O2 sensor can do tons of damage. Glad I didn't have to sell another arm or leg to fix anymore issues and thanks guys for the inputs. One less thing to worry about the car

 

Sounds like maf to me. Where did you get your replacements?

 

No it was the O2 sensors. I replace the MAF when the car wasn't going pass 40mph or had any power. The MAF fixed that but this other problem came up and wasn't fixed till I had both O2 sensors change.