First of all... I have a 91 Civic Si with a Complete JDM ZC dohc Swap it is throwing a code for the o2 sensor... The mecanic said that since on my DC sports Header the o2 sensor was farther back than the stock zc one thats why its throwing a code. anyways I need help on what direction to go to pass this stupid *** test
This is in Maryland.

 

Cant really help ya with it being a ZC swap since i'm still Dmotoring it... but i can help with Maryland.

Mine failed bad, and my O2 sensor was much further downstream than before, and only on one cylinder. But that wasn't the problem. Turned out i had 2 cracked fuel injectors, and one that was staying closed some times, and a bad O2 sensor (though mine did not throw a code). Tested it again it was better but not great. Put on a new Cat (stock one $$$) and then it passed... at the second testing station, my theory is different stations have different methods... so maybe try a different one?

Have you installed a new 02 sensor?

 

My car failed big time a month or two ago with an o2 sensor out I fixed it and it passed!
If it's throwing a code I would say replace the one that is throwing the code with a new OEM one. You could also try cleaning your IACV and checking your map and tps sensor but I'll bet that o2 sensor is the problem! If it is bad the ecu is running in a default mode that is like running wide open throttle all the time (super rich). How's your idle?

I doubt it's the position in your header I had the o2 sensor on the wrong side of my cat in my old d16 ej6 and it passed with flying colors! Maybe someone else knows better what difference that could make however!

Good luck!

 

its running SUPER rich.... I can smell it lol...
when I let off the gas it back fires and gargles.
doesnt sound normal. + I belive the ppl at noyans bumped the timing up for some reason. maybe ill swap out the 02 sensors and see whats up
thanks Tom

 

I had similiar numbers in my hf. I changed the o2, oil, cleaned the fuel injectors and added a quart of denatured alcohol to the gas with a lil less than half tank.
passed with flying colors.

 

why would you add alcohol to your tank?
basicly I just did a complete tune up and it failed so I don't know whats going on. but im on track to find out. im gonna redo the timing tonight. waiting on my buddy to come over with his timing light.

 

The alcohol supposedly reduces emissions... i'm not a chemist though. Never tried it, cuz i've heard it can ruin o-rings, seals, gaskets, etc. Some sort of internet myth/reality. Supposedly it's similar to the 'guranteed to pass' trash you can buy at walmart or wherever. It's basically cheating... not that there is anything wrong with cheating.

 

Bummer. That is real odd. I would think that the 02 sensor being a little bit further back should not be THAT big of a problem. Have you tried replacing it... theyare a preventative maintance part anyways

 

I havent tryed to replace it yet... Im running dry on funds lol and I cant find my zc maifold so I can take the o2 from there.. lol so yea but it still runs and gets me by lol

 

The denatured alcohol burns cleaner, I dunno how but my numbers were farther off than yours and it brought it back to passing.
Its worth a try....

 

get the o2 fixed, and check your cat...

my friend went thru a whole lot of **** and then got a new cat and passed perfectly...

 

..move to st. mary's county.. get inspected ONCE and NEVER get inspected again...

sorry ...i know i'm useless heh

 

in maryland. you only have 2 trys to pass. as far as I was told. and then on the 2nd try and you dont pass. and youve spent more than 300 dollers. then you can apply for a 2 year waiver.. but I just want to pass it.

 

yea i think if you just replace that o2 sensor you should be good to go, little bit of alchohol also never hurt either though !

 

nah... you get as many times to pass it as you feel like for the first interim period (6 months i think? maybe it's 3?). Only catch is the first two times go under the original $14 ya spent. Thereafter you're spending $14 every time ya go.

Also... they don't tell ya this part. If ya keep failing it over and over they give you a waiver for 2 years... mostly out of pity for driving such a POS. Well, they use to anyway... that's how i got my CJ7 through the first time. They might have changed the law since then.

note: there also might be some clause that you have to wait a few days between each testing (easier on the wallet that way atleast), probably to keep you from showing up every hour after every little adjustment in some 81 ford pinto mobile that's all clapped out and doesn't have a chance at passing.

 

lol yea Im going to go grab my other o2 sensor tommorow. and retard the timing a little so it runs in the optium range on idle...so therefor I should pass

 

Just curious, what exactly did you fail on? Can you post test results?

 

I thought I posted them but I failed both hydrocarbon and Carbonmonoxideby alot

 

Anyone that doesn't have a problem with cheating emissions shouldn't own a Honda! Fuel economy and general mechanical efficency are the most impressive honda qualities if you don't care about them, then you should own a camero!