Hello i have a 2000 civic si em1.
It has a dohc vtec engine, aem intake, ngk spark plugs, dc headers and a greddy exhaust.
I have just changed the oil myself two weeks ago so its clean. I have also put in a new o2 sensor and a brand new catalytic converter.
I have taken it to go get smogged last week on monday and it did not pass.

It passed the functions test but not the emmissions.
It failed the 15 mph test on the hc(ppm) portion it measured at 71 instead of 66 and the 25 mph passed perfectly.
So then i put fuel additive to clean out my emmisions on thursday and used up thr tank of gas till friday.

I took it again on saturday and failed again on emmissions on the 15 mph portion with thr hc(ppm) but at 89 instead of a 66. I dont know how it failed worst than last time.

Please help me out i dont know what to do ive heard of some tips to pass but i need more advice.

 

did you warm up your car before smog?

also did you do a tune up? you said oil change but what about plugs and wires?

 

The first time i warmed it up pretty good. And second i didnt warm up . I know now to warm up at least 20 mins before taking. I have brand new iridium ngk spark plugs but i need to get them installed.