my s2k just failed smog and the tech said its 3x the max for nox and is a gross polluter.

This is in California

car is stock other than cold air intake

I know my cat is missing one of those spring bolts would that cause the NOx to be so high?

no check engine lights

 

just got the paperwork back

15 mph rpm 2018
Co2 9.91%
o2 5.53
HC Max 58- mine 25
CO Max .52 Mine .02
NO Max 451 mine 2221 Gross polluter 1936

25 mph rpm 2546
co2 10.30
o2 5.71
Hc Max 42- mine 18
CO max .50 mine .01
NO max 738 Mine 2129 gross polluter 1736

ive never had problems passing before would a cat start giving that much of problem in between testing?

also is an exhaust leak enough to cause such high numbers or just higher numbers like if i barely failed?

 

ok so i hooked my car up to my obd2 scanner and looked at the live stream.

fuel trims
my ltft and stft are well into the negatives
-10 right now for the long term
and anywhere from -5 to -25 for short term

Map
intake map reading is around 11 inHg at idle

o2 sensors

bank 1 and 2 voltage around .6v to .95 v
bank 1 and 2 stf fluncuates from 6.5% to -25% and it cycles up and down consistantly like 1% a second and faster if holding a rev.

my car runs fine
i looked at my data stream not that long ago and everything was fine ltft was at 0%

 

Some thing wrong with the info you posted. Your O2 is not 5% and your CO2 is not 9-10%. Scan the VIR(smog report) and post it.

 

What are the trims at idle,cruise and WOT?

 

and the trims i posted were of idle. ill have to go out and drive it to get cruising and WOT ill post those in a bit

also do you think it matters that he put it as single exhaust when i have a duel exhaust?

 

WOW somethings really wrong, either with your car or his machine. No way your co2 should be that low and your O2 that high. Does your car run good?


(also you dont have a true dual exhaust, two cylinder heads are needed for that)

 

my car runs fine other than the sudden ridiculous negative fuel trim. literally just a few days ago my fuel trim was fine.

 

Holy smokes!!!!!!!

 

Someone pls help

 

Hard to help from the internetz, but lets see some data.....

 

The exhaust leak killed your cat. It doesn't take long for this to happen as the oxygen sensor dumps enough fuel in there to melt your cat, imo.

This happened to me so I know from experience. My cat was killed in under 1000 miles.

 

so today i decided i would look at the cat and o2 sensors and take some pics. it didnt take long at all so ill put it back together and go drive it around and try to post those fuel trims at idle WOT and cruise.

here is the o2 sensor bank 1



this is the bank 2 o2 sensor the one that actually sits in the center of the catalytic converter


and my cat front and back of the honeycomb it looks okay to me but id like your take on it

 

Ok so put it all back together and replaced the spring bolt that has been missing cleaned the o2 sensors with brake cleaner And fired her up. At first I was like oh wow look she's all better because the short term fuel trims were at a steady -2 to +2 but as the car warmed up the fuel trims began to drop back to what they were before.


I also grabbed the trims at wot and cruise


At cruising they seem to even out to be normal -4 to +4 then at wot it just says 0%

 

Were you just theorizing when you mentioned an exhaust leak or do you actually have one ?

The first oxygen sensor looks like a ghost. Can't say I've ever seen one look like that.

 

Just a theory I can't imagine a missing bolt would throw my NOx numbers that far out of whack. There was def. no exhaust leak sound. But that theory is moot now that I replaced the bolt. As far as the o2 looking a bit pale I think it's a combo of it actually looking that way and the lighting

 

It doesn't take long for an exhaust leak to kill an oxygen sensor/cat as I said before.

btw you can't clean an oxygen sensor.

 

I feel like if the o2 was fighting an exhaust leak the trims would have been off a week aga as well. Compensating for what it thinks is lean by adding fuel. But they were normal a week ago. And now it thinks it's rich and leaning the trims out by subtracting fuel but I think it's a false rich because its leaning it so far out of whack that my NOx went skyrocketing up.

 

seafoam that thing and check for white smoking coming from the exhaust anywhere from the exhaust manifold to the precat oxygen sensor...paying special attention to the flange(or wherever you were missing the bolt originally)...if it seems fine just replace your precat oxygen sensor and do a "pretest smog" if it still fails clean out the egr..if it still fails I would replace the cat...would be my advice

 

Ill try that. But my car has no egr

 

Hi S,

You either had a pretty good exhaust leak or the emission machine's hose has a leak (going off of the 02 readings). By your post's it sounds like you didn't have that big of an exhaust leak.

The cat need's to get very hot to do it job and any leak is bad.

Your ltft is the one that you need to consider, the stft should move around like that.

Could be your precat O2 sensor is getting lazy as stated before.

thesmogman

 

What a big exhaust leak. Exhaust leak before the cat will cause high NOx reading. Make sure the front O2 is working properly and all the pulse air connection is still hooked up. You can check the O2 signal using a scan tool that does graphing. Run Chevron 91 as well. And is that an aftermarket high flow cat?