The weather is starting to get nice and I need to get my car registered before I go crazy.
I have failed emissions a few times and need help with diagnosis. I don't have a lot of info, but I'll tell you what I have.

My HC level is at 4.6 and it needs to be below 2.0
My CO level is at 51 and it needs to be below 20
My CO2 level is at 529
My NOx is at 1.1

I am not throwing and codes and I have recently replaced the plugs. I also replaced the injectors with stock ones. I was told by a mechanic that my long term fuel trim was at 108, and since replacing the injectors, it is now at 128, where it should be, but it didn't help my emissions numbers at all.

Like I said, I don't have too much more info, but any help that you can give me would be great. Thanks

 

clean out your TB? back when my brother had his V6 camaro it wouldnt pass it was to high on O2 Etc after he got his TB cleaned he passed

 

I looked at it not too long ago and it seemed fine, but I will try to clean it and see what happens.
Also, I wanted to mention that the car seems to run great, just a little rich

 

how many miles? your cat may be clogged up, or have an o2 sensor on its way out

 

my camaro runs rich with the SES light on when i took it a couple months ago and it still passed so i doubt its the extra fuel.

 

the high levels of hc and co is a dead giveaway that its rich or at least not getting burned. lean it out a bit with a tune or check the ignition and fuel. a lower thermostat also helps keep the engine cool which is bad for emissions. good luck. I could not pass for **** last year, now I have an easy button

 

The car has about 125,000 on it right now. I know that the cat probably isn't perfect, but I don't think that it's my main problem. There is a bigger issue that I need to figure out first.
Also, I know that the lower temp thermostat doesn't help any, but once again, I don't think that it's the big problem.
The O2 sensor could be bad I guess, but wouldn't it throw a code?

 

ive heard of them start going out without throwing a code, and then they will go completely out and throw a code.
Mine was throwing a "left o2 too lean" code that the SES light never came up, scanned my computer and there it was

 

Is there a way to check if the O2 sensor is going out?

Also, any other ideas on what might be wrong? I might take it to a shop next week if nobody has any suggestions. I don't want to because I always do everything myself...but I'm lost on this one

 

you can have your shop throw a volt meter on o2 sensors to see if they are (lazy)them being lazy would cause co's and hc's to be high and not set a code.the low thermostat will not affect it too bad as long as they don't put the fan in front of the car and leave your hood closed/good luck!

 

I can check them with a volt meter myself, but what type of numbers should I be looking for?

 

can't remember exactly but when you flick gas volts should jump quick then back down

 

low is lean, high is rich. pulled out the old book to help you out. rich exhaust is above 800mV, lean exhaust is below 200mV. Make sure you are in closed loop before testing then take your + lead to the o2 wire and watch the voltage. should constantly be changing. a dead one will read constant. changing above 550mV would indicate a rich mixture or o2 sensor is contaminated. i cant remember how many times it should change to not be considered lazy though. maybe someone else can help

 

Thanks for all the help guys, and keep it coming. Electrical stuff is not my specialty, so all the info is appreciated.