I have a civic with 300K miles that I picked up last month.

However I'm having smog issues. Can someone help interpret?

My first test results
CO2 02 HC Max/meas CO max/meas NO max/meas
14.9 .5 94/73 .58/.38 847/1472
14.9 .5 76/20 .49/.19 786/1115

After this, I did a tune up including, new plugs, oil/filter change, air filter change, change cap/rotor, Retarded timing to 17BTDC, replace exhaust manifold gasket and checked for exhaust leaks, change PCV and o2 sensor, also ran two bottles of Lucas Oil additive that's supposed to help with emissions and preconditioned the cat before I hit the rollers

My next set of results
CO2 02 HC Max/meas CO max/meas NO max/meas
14.9 .2 94/86 .58/.50 847/1221
15.0 .2 76/34 .49/.28 786/784

The nox levels look better but still failing/marginal, and the HC levels crept up.

At this point should I get a new cat? I'm not averse to the idea but don't want to spend $200 if I don't have to. Thanks

 

man im in the same boat as you. i just pick up a wagon and try to smog it. 1st test everything passed except the NO. my results are pretty close to yours. with my NO meas around 14**.

then after changing oil/filter. air filter. spark plug. denso O2 sensor my meas all shoot up really high. HC and CO now doesnt pass. and my NO went up to 3***???? WTF!

sorry dont mean the steal your tread but i would also like some help too. already spent over $100s(including towing/fuel/fuel/fees) and havent even spent any on the performance parts. lol

i thinking maybe the denso O2 sensor but i heard bosch sensors are crap. im sure it also needs a new cat. but i mean the 1st test i almost passed i heard that NO has nothing to do with the cat.

thanks

 

well i just got my wagon to pass smog. but i ended paying $260 for it. got a new cat. and the mechanic did some minor timing and ran a few test and the NOx was at 00** but the HC and CO where just under the average. (im still confused on where the NOx went 3*** to 00**???)

and the mechanic also said that for hondas not sure what year but you have to run them HOT?! yea thats what he said. he also said when he ran it hot the HC and CO where almost at zero.

so im thinking now that maybe i didnt need to pay him that $260 to install the cat. maybe it was good enough to pass but i just needed to run the car on the freeway for a few minutes then take it to go smog. im sure your saying yea running the engine hot will cause the NOx to be high but hey it worked for me. so give it a try run some seafoam and then take it for a spin on the freeway for a while and see if that helps.

Chi925, looks like your just border line dont make a $200-$300 mistake by having a cat installed when you dont need one yet. hope that helps. the mechanic also brought up that all the smog shops back then used to run the cars before smogging it but for some reason they dont do it anymore(maybe some law...) anyways when you get there dont turn your car off just keep it on let them test it and see if that helped.

 

Think what he meant by running it hot, actually know what they mean and do to do this,
unplug the electric fan so it starts to heat up just a bit more then operating temp, say 3/4 of the gauge instead of below half, this is what reduces these pollutants. There was no need to tell you that cause most consumers would worry to much, you might have seen him unclipping something while he was doing the timing, anyways hes only helping and it doesnt hurt the car, as the fan used at these shops is almost sufficient to keep car cool by itself but not quite which safely bring your car to a higher temp slowly while your cooling fan was unplugged, nice guy for doing that honestly. congrats!
cause driving the car on the freeway a bit doesnt make it any hotter than it would if you drove down the street to get it done,
op temp is op temp.

 

Thanks for the heads up 559. I ran it hot previously but still failed. I bought and installed the cat and nox dropped dramatically. Passed with flying colors today. Congrats to us both