Car: 92 Civic Vx

Motor: 95 B18C1, DC 4-1 header, ITR cat-back with muffler

New cap, rotor, plugs, carb magaflow cat., new but might be bad o2 NTK sensor

Well, see the results to further analysis.

 

create an exhaust leak. lol jp.

high HC usually means the cat. make sure the car is really warmed up. the magnaflow might be a little too high flow.

 

.....

 

I don't want to spend on another CAT. Especially OE. I've already spent enough money. Someone let me borrow yours. I'll buy you a 30 pack of Coors Light. 102 calories per can.. can't beat that!

 

I think your combustion chamber is full of carbon.
Use Guarantee to Pass, Seafoam, or other variant

Check out my post

https://honda-tech.com/forums/acura-integra-6/high-nox-opinions-needed-2956023/

 

Its the header. Its cooling the exaust too much. Going by the O2 and CO the mixture is ok. Check the timing and make sure you get the cat really hot before the test. You can see the hc goes down once it has been run on the dyno. If you would have done it again it would have passed.

 

HC is Un burn fuel in the exhaust... Did you drive the car for awhile before taking it to get tested? You can try BG44K (actually cleans the whole fuel system not cheap but works) that helped me lower Hydro Carbons, for a last resort you can use Pure Ethinol it just mask the HC in the exhaust its true cheating.. its a cup per gal I think..

Its not the cat or header at all, because your NOx is good and so is you higher rpms HC so its still working... your running rich could try turning down fuel pressure alittle but hope you have a wideband O2 sensor cause you could make your self run lean

Dont shut the car off whe you get to the smog station... take someone with you and have it run the whole time dont shut it down

 

Yeah I drive it for 20+ minutes running in 2nd and 3rd gears in 5k-6k rpms. Upon arriving, I hold the rpms around 3k before they bring it in. They shut the car off a bit to do the visual inspection and after I pass, then they can test it. So that's the main problem. I should tell them not to shut off the car while doing the visual. So should I put back my stock header? My friend told to switch back to stock as well.

 

Should I retard timing to 15,14? I got some fuel injector cleaner from Honda. So I might give that a go.

The smog ref said to go get a diagnostic but it's $105+ and I don't feel like paying that.

 

...... what else I can do to lower HC?! If o2 and CAT is working fine.....

 

Consider the ethanol or exhaust leak methods. Get a stock exhaust and drill some holes in the resonator.

 

Put the stock header on. It'll definitely help the exhaust temps stay high to help burn hc.

 

Never heard of the exhaust leak method. I would think the idea would be to reduce the emissions being read from the tailpipe but how would it control exactly how much or what comes out?

 

I honestly dont think it will make that much of difference. Ive had several 240s with header and it passed just fine in socal. check and see if there are any cracks in the manifold before the 02 sensor. if it is cracked o2 will pick up outside fresh air come in and think its running lean and dump extra gas, which in reality is incorrect.

 

could be map or IAT that are bad... Which is making the ecu dump more fuel in... Drilling holes is a horrible idea.. not only will you not pass inspection but also will be loud and im sure they will figure it out cause you exhaust will look like swis cheese. Your MAP, IAT, O2 would be my first guess your EVAP canister could be failing...

 

What's a good brand o2 sensor to pick up?

 

Denso or NTK w/OEM connector.

 

That's what I'm currently running on.

 

Switched out to my old dizzy with my friends' OBD2 LS O2 sensor. NO reads 376 and 43.

The very next day, same dizzy, friends' "good" Bosch O2 sensor.

 

Do they make 30 packs of coors i thought it was just 24 lol

 

Where did you get your catalytic converter from? 49-State or CA-CARB? Whats the part #?

A faulty catalytic converter causes high HC and high CO

 

Do you have a properly working t-stat? Cooling fans cycle when hot?

If yes then I suggest you advance the timing. Were you running 16* advanced ignition timing on your original test? If so, I would bump it to 18. Remember you need to jump the service connector while making timing adjustments. All the other numbers from your first results look very good. I think they could take the +2 advance. Just make sure you go back to the dist and O2 sensor set up you had with the first test. The results from the 2nd test also suggest you need more advance and the NO on your third test is so high at the 15 mph range that it might go over with +2 advance. Good luck.

 

Yes and yes. I was thinking of going back to the OEM header and buying a new O2 sensor. Do I really need a new sensor? Will the OEM piece make a difference?

 

I don't think you need to do the OEM manifold or new sensor. I'm assuming your DC is US spec/CARB legal? I would try the ignition advance first. Advancing the timing can lower the HC b/c it makes for a hotter, more complete combustion. This also adds power but probably nothing noticable. The down side to the hotter combustion is increased NOx, but again, since your NOx is pretty low, I'd bet it'll still be passing. Don't advance too far or you may experience pinging or detonation which can send NOx way up and harm your engine.

After re-reading your post I now see that you have an aftermarket cat. They have been known to be unreliable. If the ignition advance doesn't help you then you may want to try getting an OEM cat on there. Good luck.

 

To the OP, what kind of intake system are you using? OEM or aftermarket?