Can someone tell me why I'm not passing emissions?

[pheonixS13KA24]

Hey everybody... Let me start off by thanking everyone who responds to this post. NICO is seriously the best place to go for advice on my S13.

Anyways, my '89 coupe is having problems passing emissions. I'm approximately 3.5 times as high as I should be on my hydrocarbon readings as well as my carbon monoxide, yet my other category (not sure what it is because I left the printout in the car!) is completely normal. I have approximately 100,000 original miles on my car, I just performed a standard tune-up, replaced the oil with Valvoline MaxLife, flushed the radiator (just thought I'd add that in), and the engine is stock (save the N1 cat-back exhaust which is too big in diameter for a N/A car, but I'm keeping it there for my SR swap; and I have an aftermarket cone filter). The previous owner told me that the O2 sensor wasn't ohming out correctly... Is this my problem? I have the stock catalytic converter on the car, as well. What's going on here, guys? The emissions workers said my exhaust could be screwing up my readings (idiots), but my brother's '89 coupe passed with no problems and he has the same exhaust and a stock engine (save the cone filter) with VERY similar mileage. Help!!!

(Sorry I wrote a story here!)

[pheonixS13KA24]

P.S.

I failed to mention that I was using my little brother's login name because my computer isn't letting my log on to my name for some reason. The signature is for his '89 coupe, which is a lot less stock than I remember... Anyways, thanks again!

[180fan]

too rich. try spark plugs, iginition wires, dist cap and rotor, and o2. check those out and see what's cookin.

[s13sr20chris]

more likely an o2 sensor, cat, maf, fuel pressure regulator, etc. if you get the hc down co will go with it. try going back with a few gallons of gas and one gallon of denatured alcohol in your tank. dont drive hard on that stuff and be sure to fill the tank up as soon as you get done.

[Camel]

not enough broccoli or beans

[C-Kwik]

Go get your printout and let us know which emission was abnormally high. It will really help to narrow down what the problem is.

[PureSXyness]

or..you could pay the guys off...

"so that'll be $150 for the smog check""wait, didn't you say $300""nope, $150""$300 right?""Congratulations you passed smog"

[pheonixS13KA24]

Wow! You guys are great... I have a '91 hatch in my garage (parts car) with an engine that runs great and passed emissions a few months ago, so I'll remove the O2 sensor from there and put it on the '89 (if these sensors are interchangeable from the KA24E to the KA24DE). I've also got a new distributor in that parts car and the catalytic converter must be in working condition or my emissions wouldn't have passed! My new '89 coupe gets bad gas mileage (about 100 miles per tank less than the '91 hatch) so I'm thinking I have a spark problem. I was told by a mechanic that it sounded like it was running rich. I also have a VERY rough idle, but only sporadically (like when starting the car when it's cold). I'll keep you guys informed on what's going on! Thanks to all who replied... Keep 'em comin'!

[s13sr20chris]

run a wire from the ground terminal of the maf to the batt negative. common nissan prob that causes rich condition.