Went to go get the car smog checked, and I failed the HC (hydro carbon) test at idle. My reading was 333 ppm and max allowable is 220. On the 2500 rpm test, the HCs were fine at 077 ppm. I passed all the other tests (CO and CO+CO2). So I can't figure out which one (or ones) of my bolt on modifications is giving me this problem. Here's what I've got on the car:

AEM CAI
JDM 4-1 header
Carsound catalytic converter
SMSP 2.5" SS exhaust
18 degrees BTDC

Other than that, the car is completely stock. I'm really hoping someone out there know what might be going on and can give me an idea of what I need to do. TIA

Casey

 

the only thing i can guess is maybe the Carsound Cat , i dont know much about emission tests since we dont have them here

 

I failed my test too, had to deal with it *ahem* another way. I think it's your headers, if they're the JDM ITR headers then they are not made to pass Cali smog tests.

 

retard your ignition timing, it'll help your HC count. you could also try a valve adjustment if you haven't done so. and you might wanna check your O2 sensors

 

In7egrity: good suggestions, thanks. How can you tell if your o2 sensors need to be replaced? My car only has 57k miles on it.

 

Your car is a beast, that's why!

 

keep your ahhem.. place in mind.. or im me where you did yours.. i'll be due next year tward august or september.. and I hav ea wierd suspician that I wont pass.. LOL

 

I would say it is the header. It is not CARB legal, you know...

 

Yes I know, I was really hoping I wouldn't have to put any stock parts back on the car.

 

Neo,
I had a 91 Teggie GS with header intake exhaust and shitty cat.
Try a couple of these before you get knee-deep in taking off your header.
1. Take intake all the way off. Buy some Inake carb cleaner and spray it on the BACKSIDE of your butterfly valve (it should be pretty dirty and you'll have to keep the throttle open when doing this with the car off of course) wipe that off with a rag.
Next, change your oil if you havent recently. Dirty oil will make your HC's rise!!!
Retard your timing, it should be at 16 degrees BTDC. Check where you timing was when you tested the car (it should be on the smog check) and retard 2-3 degrees. If you arent running 91 octane or high grade gas go and pick up a couple of gallons of 76 or Chevron. Hop on the freeway and WARM UP THAT CAT. Drive at like 80 for at least 10 minutes (if you can) and go right to the smog station after doing this. I SWEAR YOU WILL PASS EMISSIONS!!!!!!!!!!!!!!!!!!!!!!!!!!
TRUST ME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!

 

I know someone that had a GSR with the stock intake, JDM headers, high flow cat, and an rsr exhaust and it passed. Try switching the air filter back to stock.

 

use a voltage meter.. i forgot what the correct voltage was for it, but i remember you have to heat it up with a torch and then check the wires.. it's been so long since i last did it i don't know for sure.. sorry. maybe you could ask a mech

 

bring you timing back to stock @ 16. run your car hard before you get to the center to heat up the cat. and get a valve adjustment. can't promise anything though.

 

I can't possibly think of any logical explanations why it'd be the header. He's not introducing more fuel into the motor, he's just pulling the exhaust gasses out more efficiently.

What kind of gas mileage are you getting? I'd check your O2 sensors first, then check the other common maintenence/replacement parts. Your mentioned mods should not affect emmissions.

G'luck.

 

Many thanks for the replies, gentlemen. Driving the **** out of the car to heat up the cat seems to be a consensus favorite. Come to think of it, yesterday was a very cool day in Atlanta (~45 degrees) and I only drove about 1.5 miles to the shop to get tested. So that might be what caused me to fail. But I'm also going to check the plugs and distributer (cap and all) to see if everything checks out. Thanks again.

 

retard your timing to less than stock. that seems like its the problem. the only reason why the header wouldnt pass is if the header didn't have the correct location for the O2 sensor. Intakes add no smog. The cat and exhaust should be fine, too... UNLESS the cat is burnt out and needs replacing. If the cat is burnt out, then you may hear a slight rattling noise from your exhaust. Retard the timing to about 10, get some good gas, and go get smogged. You should EASILY pass! If not then the problems lay elsewhere... header's O2 sensor location or bad cat.

 

the cat is brand new (been on the car since Sept.), so I doubt that's the problem. Timing, new plugs and other things will probably get me passed this hassle... Thanks.

 

retard the timing to about 14deg and maybe lower your fuel pressure if you can. drive the hell out of the car and make sure that converter is really hot.