[SMD]

Hi I have a 2020 Camaro SS fbo. It’s been about 7000 miles since bolt on and tune no problems. I noticed my exhaust was smelling different and on cold start up the idle surges and almost stalls hunting. Will also pop a little on the high way at 3000 rpm and let off the throttle. Put it on the scanner and no codes. Checked some sensors (not a mechanic so some stuff is foreign to me) but I did notice that my O2 sensor 1 on both banks was reading .05 volts super lean and my O2 sensor 2 in both banks was reading 1.9 volts super rich. No miss fires ? It was in closed loop and I know that O2 sensor doesn’t really tell the ECM to do much just the #1 sensor before the cats. Do you think I have bad cats? Anything else I should look at on scanner? Any help would be appreciated. Thank you

[ctrlz]

you can pretty easily find expected ranges for these online.
pre-cat will oscillate and post-cat should be constant low

[SMD]

I looked and .45 volts is normal 1 volt is very rich and .10 volts is very lean. I’m way out of those ranges

[ctrlz]

Originally Posted by SMD

I’m way out of those ranges

I agree.
Hopefully someone with tuning experience chimes in.

[KingLT1]

What do your long term fuel trims look like?

[Megahurtz]

check for leaks pre maf, post maf and in the exhaust. You likely have no codes because the tuner set them to no error reported. You will need a scan tool like HPTuners to take a look at what is going on with fuel trims. Could be a bad O2, burnt O2 wire, or failed Cat. When the O2's are messed up, the fuel trims go way off and make the car run like garbage.

[SMD]

Thanks for getting back to me. My scanner does do live data. Should I look at fuel trims at idle like I did with O2 sensor I just rev it a couple times ? And should I look at anything else ? Thanks again

[SMD]

Also my exhaust leaves like black soot. My exhaust is ARH long tube with high flow cats. And I did see something on my scanner don’t report MIL or something like that

[SMD]

Scanner results

[RobZL1]

Looks like you have Voltage out of range and no current flowing on both post-cat (S2) sensors. Are you sure they are connected?

[Megahurtz]

Fuel trims don't look unusual in that snapshot but its really the whole range to look at. Make sure you don't have fuel trims that are exceeding + or - 10-12% at any RPM range or where bank 1 or bank 2 are vastly different.

IF your cat is clogged, it would seem down on power and the header would get very hot and possibly glow when it dark out side. If you have a laser temp gun you could check the temps of each header primary and make sure there are not any large differences cylinder to cylinder.

I'm assuming you checked your plugs and wires already? Make sure the plugs are good and no burnt or loose plug wires.

[SMD]

Thanks for the help going to put it on jack stands and look at rear O2 sensor and wiring. I did a visual to the plugs and wires Didn’t actually pull a plug since I wasn’t getting any misfire. Guess I’ll check them as well. Thanks again

[SMD]

Update the #2 sensors after cats are installed but the wiring is cut clean. I’m assuming the tuner did that and did it for a reason so I guess that explains the bad readings but now that I’m looking at the #1 sensors (that are wired in)there is practically no voltage should be about .45 volts and the amps should not be milliamperes. Do you think I have bad O2 #1 sensors or am I just chasing my tail. Thanks for the help

[Megahurtz]

The front sensors should be switching from very low voltage to high voltage. (.100 - .900 or so).

If they are not switching then you potentially have bad sensor(s) or wiring. But its also possible if they are stuck at a low voltage the car is actually tunning lean and the cause is somewhere else. But your snapshots would have shows very positive fuel trims if the front O2 sensors were stuck showing lean.

I'd look up some videos on YouTube about how to use your scan tool to check for bad O2 sensors.