I need emissions help. I live in Connecticut and my car failed emissions. I have a 1990 Honda Civic Si. It has fresh 93 Octane gas from when I went the Danbury Meet on June 7th. Back in October of 2005 I passed emissions with everything I have on the car now. I have an intake, Wrapped header and a High-flow cat(All very low mileage). Everything is stainless. Here are my numbers from 2005: HC 117(Limit 188), CO 0.45(1.00 Limit), NOx 1436(2188 Limit). I have only put 2,359 miles on the car, It does not get driven much. When I searched, One of the things that was recommended was to replace the o2 sensor which I did today because it failed last week. Here are last weeks numbers, The limits are the same: HC 72, CO 0.40, NOx 3526. Here is today's results: HC 76, CO 0.56, NOx 4209. I don't understand why the NOx went sky high after replacing the O2 sensor with a brand new Bosch OEM fit replacement. I never received the notice for emissions that I was due in October 2007 and now I need to renew my registration in August. I need the car to pass or I will lose my registration. I do not have very much money so I need to do the work myself with limited time left before my registration ends. I have not tried to do the Seafoam through the Fuel Regulator Vacuum Hose trick yet. I am at a dead end on what to do since replacing the O2 sensor made the NOx sky rocket. Emissions guru's please help me with your ideas.

Thanks,

 

I hate to say... But I think it is the high flow cat.

Usually they are good for one, maybe two smogs.

Just get a aftermarket replacement cat to put on just for smog's then swap them.

Check your timing. a few degrees will lower the nox some.
Use Seafoam if you have build-up. I suggest you don't put it in the oil.
Exhaust leaks before the cat or O2 sensor and effect things too.

Old gas will raise the CO. And why are you running 93 try 87 it burns cooler and is easier to ignite.

So there's a few to think about.

 

I really appreciate your help with my emissions problem. I am going to get a Magnaflow stainless catalytic converter for my car when I get paid at the end of this week. I found an OEM fit for just under $100.00. I have one more question for you, Since my NOx went up after changing the o2 sensor to a new one, Do you think I should put the old one back in? I'm gonna run 87 octane like you suggested, I also ran through the Seafoam on the fuel regulator vacuum line as per your instructions in your archived post. Please let me know what you think. Thank you so much.

 

I would stay with the new 02 sensor.

$100 bucks is not bad at all. I paid $87 for mine. It is just a cheap replacement cat.

Did you set the timing? Just a reminder! My car likes the timing at 16btdc and my spec is 18btdc.

Also after you install the cat give it a break in run for about 20 freeway miles.

I am pretty sure about it being the cat. Good luck!

 

Ok,

I retarded the timing by loosening the bolts on the distributor. The bolts were originally locked just about in the middle of the adjustment slide. I rotated the distributor as far toward the headlights as it would go(about 1/4"). The idle went down a hair, But it still runs smoothly. It definitely lost some top end speed and also some low end power. It still runs smooth throughout the RPM range. I did not have a timing light to check exactly how much the timing is retarded. Is it possible that I could have retarded the timing too much? Could it cause the emissions to go up or will it definitely go down because of the retarded timing? I am getting my catalytic converter tomorrow via UPS. Please let me know, I am still learning and I want to make sure I pass.

Thanks so much for the help,

 

I'm sure you probably already know but...make sure the engine is good and warm before the test. I'm not sure of the mixture, as i have never had to use it, but I've heard a little bit of denatured alcohol will get you through the test(I don't know where to get it). I personaly always use a bottle of dry gas/in tank fuel cleaner before a test.

 

You should of only moved it a very little. Say 1/16 of an inch or 1mm. You went way to far. Can't you borrow a timing light from someone?

 

I have a question about the timing, I want to adjust my timing, so you just loosing the bolts on the dizzy and move forward to retard correct using a timing light? Mine is set at 16 was thinking of setting at 14 and opening the gap on the sparkplugs to make sure it passes

 

If you have a timing light then just make sure you are setting it to what you want. For smog the tech is suppose to check timing and on Honda's it is at spec +or- 2 degrees. don't go over that.

 

Did you have it good and hot when you tested? I've been close before and just taken it down the highway then drove through and passed.

Do you have a newer Honda distributor cap and button? What about wires? Those have made a diffence also on the same car as above. There is definitely a difference in the Honda parts and the cheap stuff. I only run the Honda ignition components.

 

I put the timing back where it originally was, I am in the process of trying to find a timing light I can borrow. Because I have aftermarket exhaust I need to modify the catalytic converter, It only has a 2" opening and my exhaust is 2 1/4". I need to put a larger flange and expand the pipe a little, My local muffler shop said they can do it for me. Everything is top notch as far as tune-up stuff goes and yes it was hot, I agree with thesmogman about the problem being the catalytic converter since it is a high flow design. I appreciate everyones help, I will keep you posted.

Thanks,

 

Good news,

I passed emissions. Thank you all for your help. The NOx is still kind of high but it did pass with a 2060(the limit is 2188). The new catalytic converter did help but I could not find someone with a timing light so I just left the timing where it originally was. I broke in the new Catalytic converter with 80 miles of driving, I also replaced the PCV valve and put in new spark plugs for good measure. On today's test the CO dropped quite a bit to 0.06 from the 0.56 it was before. The HC is better also, Down from 76 to a 48. Even though I passed it still concerns me that the NOx is still high. I need to go through emissions again on October 23, 2009. It did concern me that the NOx number went up after replacing the O2 sensor with a new one, So today I exchanged the new O2 sensor for another new one just in case the one I received was defective. Do you guys have any other suggestions on how to bring the NOx down a little more? Please let me know.

Thanks,