Hello HT,

Long time reader but first time poster. I bought a 1993 Civic VX swapped with a B20b/GSR tranny years ago. I wanted to get it BAR'd so I purchased a local 1994 LS B18B1 and replaced the B20 with it. I bought the corresponding ECU from a salvage yard and all that jazz. Worked at getting it to pass but ran out of time because I had to move away to go to college. Failed the first attempt at both speeds and the second attempt at the 25 mph test. Here are the numbers;

15 MPH
RPM : 1877
%CO2 : 14.3
%O2 : 1.1
HC (PPM) : 47
%CO : 0.03
NO (PPM) : 2020 - Gross Polluter (Max 708)

25 MPH
RPM : 2053
%CO2 : 14.4
%O2 : 1.0
HC (PPM) : 30
%CO : 0.03
NO (PPM) : 742 - Pass (Max 746)

Though I passed at the higher speed, it was still close. I put a Magnaflow cat on the car because it had a test pipe on when I bought it. Installed a new Nippondenso O2 sensor. Not pulling any engine codes at the moment. The fuel system is what the car came with, not sure if it had been upgraded when the previous owner dropped in the B20 (B20 has AEM fuel rail, B18 stock). I ran that guaranteed to pass smog junk in the tank between the first complete fail visit and the second half fail visit in addition to having a full tank of 91 octane on the second visit. I'm new to Hondas but am a capable mechanic. If any additional information is needed let me know. Would love to get this car on the road here in Oakland. Thanks.

 

I thought I would just post images of the Ref statements to make things easier to diagnose. Timing was reduced from 17 to 14 BTDC between tests. One thing that stands out to me to compared to other ref problems I've seen on the boards is my O2 levels, is that a good indicator of leak? Anytime I try to research this I get tons of articles on oxygen sensors. Any help would be much appreciated.





Here's the baby

 

Way back when I used to smog if it had too muc nox I just added another cat inline and went back and the nox dropped a lot.

 

Ok, I'm about to get the jack out and get under and check for leaks and give the new O2 sensor a spray with some cleaner.

 

I got my timing belt done at a shop. Long story short, they f'ed up that job the belt was off one tooth on the intake and exhaust. That brought my timing to 37*BTDC! Had to tear it apart and put it in right and put the timing back to stock 16*BTDC.

So check your timing.

 

And did this cause you to fail a smog test? From checking under the car it appears I might have an exhaust leak after the cat. Would this influence NOx levels, I feel this could explain the O2 readings in the tests.

 

Found exhaust leak at rear passenger side wheel junction. Nothing up front or near cat. Can any smog experts help interpret the emission data?

 

I have a lambda calculator that estimates your air/fuel ratio based on emissions numbers.

It says you were at 15.48:1 on the 15mph failing run and 15.38:1 on the 25mph passing run. A lean AFR will lead to higher NOx readings because of higher temps.

From that, maybe look at the fuel system causing you to run a bit lean? Maybe a slight vacuum leak? Since vacuum leaks have more effect at idle, maybe the leak is masked enough at 25mph to make you barely pass?

How does the car run in general?

 

Yes I failed NOx. Timed it correctly and it passed with minimal NOx readings.

 

Thanks for the reply Bnet, I read your thread after typing that post before, sorry about that. I jumped the service connector and set timing to 16 BTDC, was slightly advanced. Hopefully that small tweak might do the trick, especially because I only failed the 15 mph test. Another question, could I have the car tested at any smog station just to check if it will pass before I go all the way to the ref? The swap looks pretty incognito, I'm guessing any smog tech that doesn't know Hondas will not even notice. I just want to get this thing on the road so I can get it BAR'd.

 

For the guy that said you just put another cat inline that is freaking illegal as hell. Plus it doesn't even work. The first cat absorbs all the oxygen with then makes the second cat useless.

As for passing you obviously need a better quality cat. I dont see you dropping that much nox from just retarding the timing a little. And like the previous post stated, check for vacuum leaks

 

Thanks. Yeah I wouldn't consider putting on a second cat because that would just be beating around the bush. I did find that the timing was probably about 20+ BDTC when I jumped the service connecter, so I set it back to 16 BDTC. When I get my next paycheck I'm going to take it to a smog/muffler shop and have it tested. If it doesn't pass then I will just get a new cat from them. Sucks because I went and paid for the Carsound one. If I pass it I will then go pay a visit to the smog referee and get legit