I just bought a Honda civic hatch 96 and I took it to get smogged and it passed the first test but the computer said it needed a retest then I failed, I had 104 on hydrocarbons and my max was 100 so four points over... he told me my car needed a tune up because it was sitting for a while 6-12 months I'm guessing... so I put new spark plugs and wires on it and I gave it an oil change, then I added seafoam to it at half a tank of gas, in the brake booster and gas tank. I drove it to empty refilled a quarter drove it back to empty and refilled it all the way using shell premium. Its been a week and a half and with my job I drive alot between 20-150 miles a day, and smoke still comes out not when I'm idling but when I rev it to about 2500-4000 after 4000 no more smoke but in between there is smoke. I also had a crack in the weld on my cat but I had it rewelded but he said there was a little part he couldn't get without taking it off,(20$) I don't know if that effected it, the guy just put a pipe up the exhaust and ran the test... so now I don't know what to do without spending a ton of money.