Read my post on this smog issue. Without your readings we can not help you much but I have done many things to pass smog a few months ago in the bay area myself. I have (count them) 8 tests to prove it. The only thing that worked was a new CAT, everything else including additives had no effect whatsoever.
If you are having HC issues you will need a new CAT and maybe a O2 sensor.
It would be good to see your smog results though.
Your numbers are pretty bad on both HC and Nox. Worse then any of my readings ever were on many tries.
I'm pretty sure you will need a new cataytic converter and when you do that I would also change the O2 sensor.
The catalytic converter may not be enough though, on mine my Nox got reduced by a factor of three and HC was reduced by 40%.
Anything else I did like fuel additives, fuel injector change, Lambda mixture adjustments (at the dealer with tail pipe readings), oil change, spark plug changes, rotor, cap etc either increased the readings or made no significant change.
Is your cat the original and how much oil are you burning?
Cat is not original. Purchased at complete exhaust system (cat, muffler and manifold) 2 years ago and passed smog. I ran the seafoam through the intake manifold, no sign of burning off carbon. None! Also, I'm not losing any oil at all. Slight seepage from the valve cover but not enough to even show on the dip stick. Thanks
Is the new cat OEM or aftermarket? If aftermarket (like mine) I heard they have a 1-2 year life.
If it is not your CAT and you do not burn oil to mess up your CAT, you have a more serious problem.
I would like to find out if the Seafoam does anything for you but I tried two different additives in the fuel myself with no effect, both were highly rated and both were provided by the dealer.
High Nox generally means your combustion chamber is running too hot, high HC means your air/fuel mixture (lambda) is running too rich or you have an ignition problem.
It is a hard system to diagnose. I'm probably preaching to the converted here though.
Good luck! And let us know how the tune-up and Seafoam works out.
Actually purchased the complete exhaust system off of craigslist. Left that bit of information out. I will let you know how it goes. I broke my brake booster line, don't ask, replacement arrives Tuesday and then hopefully pass smog on Wednesday! Fingers crossed. Thanks
ouch! Send the second set of smog results (along with the limits as 88 maybe different that mine 89). Unless your ignition was way out of tune for the first try a pass would be a miracle on the second. I maybe able to help you in your next step based on my recent experience.
Interesting item, When I went to remove my brake booster line, at the manifold it was quite loose. Maybe a false high reading on the smog test? Or slightly elevated as a result. hmmmmmmm
Let's see if the factor of 3 reduction with a new CAT holds for you as well.
Hopefully the only change you made is the CAT. That way it is a controlled experiment.
Did your HC pass?
Congratulations!
Can you remind everyone just what was done (Cat+ O2 sensor or Cat only) between the last reading and this one?
Also what brand CAT was used?
Sure! Only replaced the Cat, which I purchased on Amazon for $101 (Today it's $124), MagnaFlow 338004 Large Stainless Steel CA Legal Universal Fit Catalytic Converter. All's well.
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