Help! I failed CA smog again for the second time in 2 years. My car is an '89 with 178k miles. It has fresh plugs, fresh oil, newish cap and rotor, a brand new oxygen sensor and the cat (weld in type) has barely over 20k miles on it. All vac lines look good. I regularly run techron in it and I had a full tank of 89 octane when I took the test.

The biggest problem is NoX. Pass is around 850 and my car is testing at over 3,000 (15 mph test). It is somewhat lower at 25 MPH, but still not anywhere near passing.

Could the cat be bad after only 20k miles? Someone suggested that they are only good for a couple thousand miles. I am at my wit's end and would hate to retire my daily workhorse by donating it.

Thanks!

 

high Nox #'s are from a lean condition. I didn't see about you replacing the fuel filter? timing was spot on? (ignition/cam) A bad cat would usually yield high HC #'s

 

on your smog form, what did it measure your timing at?

 

From my experience with high NoX numbers on my sohc zc, it was due to carbon build up. Its very good that u run the techron cleaner from time to time. 3,000 is super fukin high. That leads me to believe its a combination of things. Tell us the rest of your number (HC and CO) as well as your timing.

 

I dont think your cat is the problem. Cats on the CRX i believe are 2-stage, which means they only correct HC and CO levels, as opposed to 3-stage ones which correct NOx. Don't take my word for it though

 

Thanks for the info. I don't have the form in front of me but I also failed HC's at 15 mph, barely passed at 25 mph. It was not super high like NoX, but it was still high enough to fail. On my last smog test two years ago (non dyno test) the numbers were great. My cat was brand new at that point.

Timing was about 18/19 degrees which is right according to the underhood sticker which specifies 17 degrees +/- 2. I have not changed my fuel filter since I have owned the car (owned since 155k miles). The car had a bunch of work done to it prior to my purchasing it. I made sure to warm the car up before the test with a 25 mile ride (much of it at 65 mph in 3rd and 4th gear).

Someone suggested the EGR valve, but would that cause such high NoX? I don't want to throw money at the car blindly.

Keep the good info. coming.

Thanks!

 

get an illegal smog. from the looks of it, it'll prolly cost the same fixing your emmission problems.

 

If you post your 5 gas numbers I may be able to point you in the right direction. I am studying to get my smog license.

NOx created by high temp and high pressure
HC is unberned gas (raw fuel)
CO is incomplete combustion

CO2 Higer the number the better (sign of combustion efficiency)
O2 should be less than 1%


If you have a lean condition, you most likely will have a lean mis-fire High NOx & High HC

If your car is equipped with an EGR, if it is not working properly, i.e. if it is not opening, you will have Higher temp because EGR is to dilute the mixture so that the engine will run cooler

 

If you've been running with high HC for a long time, it is possible that your cat is dead. even within 20K miles. The CAT is to burn what is not burned and to reduce NOx and HC. If the CAT is fed a lot of HC and O2 from the misfire, it will drive the CAT too hot and possible burn-out of the cat (thermal melt down)

but if the cat was dead, your HC would have gone thru the roof too, so your cat may not be dead but it's efficiency may be reduced.

hope this helps

post the gas numbers and I will see if I can get some proabable answers for you.

 

I was in the same boat as you. Almost the same numbers to. My nox was up past 3000 ppm on both tests. I was told that the cat was replaced last year, but it was a shitty weld in type. I ended up replacing the cat with another new shitty weld in, retarded the timing (within spec) to reduce combustion chamber temp, ran top engine cleaner to get rid of some of the carbon build up, and took it back. PASSED with flying colors!! Hope this helps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by iluvjasmine &raquo;</TD></TR><TR><TD CLASS="quote">get an illegal smog. from the looks of it, it'll prolly cost the same fixing your emmission problems.</TD></TR></TABLE>


^^^ He is right just pay the person who does you smog $200 and they will make sure it passes smog. That what I had to do, and it worked out just fine.

 

As stated before, NoX is from high internal temps.
This can come from many things including running too lean, running too low of an octane fuel, and from high compression.

3 things I suggest you should look at:

If you have an EGR (supposedly only on HF's as well as California model DL/LX's that had auto trannies) then remove it and clean out the intake manifold port to get all the acrbon builup out of it. Use a fat pipe cleaner or some sort of scrub brush with carb cleaner or some other sort of solvent on it. I've used brake cleaner before and it has done wonders.

Since you have an old car with an old engine then running Seafoam may do you some good. There are several methods to do it, but Seafoam seems like the latest fad so should easily find info on how to do it. The idea is to clean out carbon build-up from the combustion chamber and piston tops.

Ensure that you have a 3 stage cat. Ensure that your timing is set as close to 0 as you can get it. Run the mid-grade octane fuel.


Oh - do NOT have any injector cleaner or crap in the fuel tank when you test.
On a stock engine you shouldn't need any help and sometimes that "help" can actually be the cause of failure.

 

Wow. This forum is great. Thanks for the replies.

Here are the actual test numbers.


15 MPH (1849 rpm) 25 MPH (2018 rpm)

CO2% 14.4 pass 15.0 pass
O2% .4 pass 0.0 pass
HC PPM 215 Fail 52 pass
CO% .56 pass .43 pass
NoX PPM 3294 (fail) 822 (fail)

As stated before my car is definitely in tune so I am at a loss when it comes to finding a reason why the numbers are so high. The EGR functional test says "N/A" so i'm not sure if my car has an EGR (car is a 5 speed manual). Any advice or help is much appreciated.

Thanks!

 

I had the smae problem..it was a freakin vaccum line on the back of the throttle body i dont know what the hell it does but it cost me 300 to get it fixed.

 

I'll take those numbers to school and ask my instructor and the shop techs to see what they may think it is. I think it's the cat. The O2 is low and CO is low. I can't think what could be causing this. I will let you know on Tuesday evening. Good luck.

 

did you pour any fuel cleaning additives? i did that and forgot that my tank still had the additive in there and did smog and my nox read the same as yours. i put a new cat on and i passed smog with flying colors.... also check your o2 sensor and vac lines. change ur fuel filter, and pour 91 octane or higher and if u want run ur car as hard as you can before u go for smog. get all the carbon and nox n hydro's out of ur tail pipe as much as possible

 

maybe try this http://how-to-pass-smog-test.rxp.com/ i havent used it but it might work

 

those numbers are great, im trying to smog my b18c and my numbers are like 5x more than yours =]

the seafoam idea is good. seafoam sucked thru vacuum (intake manifold) will burn and clean out the carbon buildup in the combustion chamber. carbon sucks up fuel vapors so that it's harder for the combustion to be good (not all fuel is used) leaving you with a. a higher HC count and b. a higher NOx due to lean combustion. that seems like what your problem is. watch out, though, because seafoam type things are not always safe for your cat and o2 sensor - i would take those out before dealing with it.

if you wanted you could take it to a test& repair station, because really, your condition isnt that bad.


i believe CO is always (chemically speaking) caused by rich conditions, so you're probably not rich
low o2 i think means that your cat is catalyzing the o2 coming out of the combustion chamber, which doesnt have to be a bad thing

im not so sure that your car has an egr valve.
good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18-c-rx &raquo;</TD></TR><TR><TD CLASS="quote">

watch out, though, because seafoam type things are not always safe for your cat and o2 sensor - i would take those out before dealing with it.

good luck</TD></TR></TABLE>

Thats what i would do.

 

You guys are great. Thanks for all the advice. I would rather use seafoam as a last resort. I can get a new catco cat welded in for $120 (discount from the same muffler shop that installed one two years ago). I may go that route.

b1r469, thank you for running my numbers by your instructor and shop techs. I am eagerly awaiting the responses.

Will running 91 octane really increase my chances of passing? Since the engine is stock will the higher octane really burn cleaner?

Thanks!

 

Hey dood, I'm from CA too. ANd i recently bought my crx which had Nox at 1,550. Crx was all stock. I put a new exhaust system, New cat, new spark, new fuel filter, new radiator, new spark wires, oil change, transmission oil change. Tested it again and it went down to 1010 NoX. To pass u need about 812 i believe. I was worry just as how u are knowing that CA's Emission law is a fucken pain in the ***. So like u, i came on H-T and ask for advice. I did try that sea foam that i got from NAPA autostore and use it all. Retest it again and my NoX was at 912 this time. so damn close. I need to get 812!!!!!. THe last thing i haven't done is mess with my timing and that alcohol method. LOL. So u might wanna try sea foam first. Then timing, then alcohol. After that's all and done and u still didn't pass. There's places in Ca where they sell you illegal smog papers -_- for a big fee of about 120-180 dollars.

Hope that works.

Til this day i haven't pass smog. **** it. Awaiting B18 swap then I will try again.
**** the stock engine -_-

 

guys,
I recently took my car (today) to a smog pretest station for my b18c. I monitored all sensors, found minor probs, tweaked, concluded that everything but my cat was working pretty well, and had a new cat welded on for 50$. I passed. From gross polluter in NOx (like 3000 ppm i think) to 39. 3-stage cat all the way.
91 octane is good for cleaner combustion (a chemical property). you're pretty close, i'd run it. maybe you can try some techron too, i'm not sure exactly what it does, but it is supposed to help clean your engine.

 

you are running lean which increases combustion temperatures and that is also causing HC's to be up due to some misfire. check your fuel filter TW sensor this it might be giving you false readings and will not give you a DTC. replacing a cat is the last thing to do, don't jump the gun. diagnose the cause for high NOX it can be mechanical or electrical.

 

From my understanding of how octane works; octane is an anti detonate. Higher the octane the slower the burn. Usually with high compression, it reduces the detonation (pinging) in the combustion chamber. Lower octane is more volatile. If you ran it with regular octane on that test, it wouldn't hurt to try high octane. On hi compression engines, it reduces NOx.

 

I read here that many people are useing the p28 and p30 ecu's. Can i pass smog with my pw0 ecu? Is there anyway?