Took my car in for California Smog Check. Failed due to high NO numbers. Everything else passes, including visual.

Smog numbers:

speed RPM %C02 %O2 HC CO% NO(PPM)
15mph 1628 14.6 .2 0 0.1 1133 (430 is a pass)
25mph 1901 14.6 .3 0 0.16 1016 (717 is a pass)

Right now my only mods are KN drop in air filter, Motordyne MREV2 and 5/16 spacer, as well as a Technosquare L-spec flash (higher rev limiter, Fully open throttle at WOT). As far as these mods go, I don't think they are making me fail. Could be wrong...In the past I had a Turbonetics kit, so the cats and headers have been off the car at one point.

Anyone have any suggestions? Was thinking about checking my PCV valve and Evap connections and replacing my O2 sensors. Could my cats be bad after only 6 years? They were not on the car while I was turbo'd. I'd like to not take it to a smog repair facility. It seems like they could replace whatever, pass it, then charge me a crapload.

I drove it for a little while before taking it to the smog shop, but forgot to romp on it a bunch.

Thanks for any suggestions.

 

i believe they have some fuel additives to help you with this. you put it in your tank before you go for your inspection. make sure you drive it around for a while to get your engine warmed up. get your car on the highway.

 

also up your psi as high as you can, that will decrease the output somewhat.

 

You mean tire psi?

Anyone tried de-natured alcohol in the gas tank? Heard this might help.

 

I believe he is rite u should might need to get a fuel additive but i would suggest that u might have just got a bit of bad gas and need to run it till near empty and then refill on premium. i usually go with bp or chevron.

as for the denatured alcohol i would not recommend putting that in your car it can act to change your octane and is very corrosive towards certain rubber and plastic in your fuel lines.

after u get some new gas in there drive it for 10 or 15 minuets after your engine is warm, catalytic converter's take longer than a engine to get to a sufficient level for burning excess fuel and carbons

hope this helps let me know how it goes

 

Thanks for the replies. What particular fuel additive would you recommend?

 

Well any octane booster will work just make sure its not a fuel injector cleaner as well.

pick your favorite brand there all prity much the same my favorite is STP. but that's only cause i picked the habit up from my folks lol

also you only really need to use it if u got bad gas, so one time in the tank with some frees should do the trick. using it constantly with a good 93 wont do much for u unless u have a high compression car.

 

15mph & 25mph? That's how they test you in socal? Anyways here in Norcal they test you @idle RPM and cruise RPM which is 2500RPM i think. From the looks of your failed numbers i would swap out cats and retest. The passing numbers and failed numbers are pretty significant so i don't think a fuel additives will decrease your numbers that much. But then again i'm not an expert smog tech. so i could be wrong. just speaking from past experiences of having cars fail smog for same thing. GL with the retest..

 

A former G owner that worked on my car previously suggested that since I was previously turbo, it might help to pop out the O2 sensors and spray them with electrical contact cleaner. I had a Turbonetics kit that used to run stupid rich at WOT, so he figured there might be a buildup on the sensors.

Gave it a try this morning. Couldn't get the upper right bank O2 sensor off (no leverage and wrench was too big to move around in the tight quarters). Upper left bank O2 sensor was blackened close to the base. Electrical contact cleaner didn't really seem to make a visual difference for this sensor. Both lower bank sensors (the ones screwed into the cats) looked pretty dirty. The electrical contact cleaner actually seemed to visually help with these 2 sensors. Will probably give the upper right bank another try with a stubby wrench. Then I'll retest.

I'll post my results.

 

Let me tell you, I dont miss those smog test in cali

 

Simple.. Seafoam.. run this bad boy through your engine and all your build-up in the engine will be flushed out the exhaust system.. It should really clean up the exhaust fumes after it finishes burning off. Make sure you replace the oil within 300-500 mi after using the product too. ..
You can also use it in your gasoline as well to help clear up the injectors

 

I used some seafoam in the gas tank. Still failed, actually didn't make any difference. So put it in the crankcase right? I've done this in my 240sx right before oil change and then ran the car at a idle for 15 min. Doesn't it thin our your oil a bit? Have you driven with seafoam in the oil in your G?

Thanks for the advice.

 

^^ I have used seafoam on the G twice before. once around 40K miles, and again when I hit bout 85,000.

Like I said, it does affect your oil somewhat, so it's best to do an oil change within 300-500 miles.. plus,aside from the some light thinning, sometimes you get large debris /gunk build up since there's no where else for those contaminates to go.
I suggest using it through the throttle body or look for a vacuum line (maybe 3/4 can or so and use the last 1/4 in the oil since you've already placed some in your gas.. when pouring through the throttle body or vacuum, it should stall the car out)...wait 15-20 minutes, and then start the car up..you'll notice the fumes coming out the exhaust)

The best part is smoke shooting out the exhaust with all the pollutants in it

 

Which vacuum line are you using to apply the seafoam?

 

illegal smog perhaps? =)