I failed w/ a 98 civic hx.

Hydrocarbons (ppm)
15mph: max:64 measured: 114
25mph: max: 47 measured: 55

After doing some research, it seems that the consensus is that the fuel is not burning completely during combustion. So here's what I'm gonna try.

1. advance timing: to allow a more complete burn inside the cylinder.

2. new plugs/cap and rotor: to ensure no misfires.

3. add rubbing alcohol to gas: I think the idea is that alcohol burns faster? not sure how much to add though.

4. remove intake filter right before testing: more air = less leftover HC's

5. beat on the car just before testing: hotter cat.

Please let me know if there's anything else that you guys can think of, and if I have the right idea.

 

a lazy or malfunctioning O2 sensor will effect hydrocarbons hook up scan tool and test O2 sensors also i wouldnt advance the timing i would set the ignition timing to its correct setting although on a 98 car iam not sure there is any adjustment

 

have you recently adjusted valves? If so, you may have one that is just a tad too tight that can cause slightly high H/C's and may sometimes illuminate check engine light. You may want to check your valve clearances. Also, may want to make sure EGR system is operating properly and not possibly hanging open. I wouldn't recommend adjusting timing just yet. I would have to agree with above and encourage you to have technician hook up a scan tool and take a look at the long term and short term fuel trims to see if ECM is commanding rich for some reason. Yes, lazy O2 sensor could be culprit, but definitely want to diagnose before just throwing parts at the car in hopes of a fix.

Hope this helps

P.S. Are you sure emissions station properly warmed engine before testing. With numbers out just a bit, they may not have achieved full converter efficiency before test.

Just a thought...

 

That sucks.. only in you were in so cali.

Check the sig.

 

Try filling your tank with the lowest octain gas you can find... It burns faster.

 

Most of the I would recommend high octane, because it burns more efficenctly. I don't recommend beating on the car before the test, cause this can cause damage do your cat (makes it red hot, and melts away the internals) and this also increases NOx.. Seems like you didn't fail under that category, but it can cause you to fail. Advancing the timing above spec will also cause you to fail if you don't stay with in the 14-18 degree range (that is the range isnt it?). Just my 02.

Oh yeah..removing your filter... you really wanna risk sucking in dirt??

from my experience.. sometimes new cap/roto/lugs increases HC.. it's weird.. but it happens.

Oh yeah..another thing about your timing, advancing it will only increase HC.. you have to slightly retard it.

Where in the bay are you? and how much do you pay for your smog test? maybe we can work something out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Oh Crap &raquo;</TD></TR><TR><TD CLASS="quote">Most of the I would recommend high octane, because it burns more efficiently. </TD></TR></TABLE>

I was under the impression that lower octane burns easier and faster. The reason we switch to a higher octane is because the lower octane fuel is more prone to pre-ignition or detonation. You can extract more performance out of a higher octane fuel because you can increase your compression ratio, crank up the boost, advance your timing or what ever it is you need to do to get more hp (depending on setup).

This is why when you run a high compression NA engine or high boost FI engine you must run a higher octane to keep from blowing it up.

Therefore I would imagine that you would get more of a complete burn with less timing advance with a lower octane.

Maybe I am wrong.

 

You're right about how low octane burns "faster". But faster doesn't always mean more effecient. Low octane has more of an erratic combustions.. meaning that it will ignite in several different areas causing some engines to ping. Higher octane ignites from point of sparks and radiates to the head of the piston making everything smoother/efficient.

Simple test. Pour a full or half tank of low octane, listen to how it idles.. and take note of how it drives. When you're near empty pour in high octane, and do the same thing. You would notice in most cases, with higher octane your car will idle slightly better because the combustion process is somewhat more "complete". Just my o2.

 

good news guys, I did everything listed in the original post (except the rubbing alcohol and filter removal) and I PASSED!!!!!!!!!!!

 

one thing i do in canada... i put like 1 gallon of gas line antifreeze..

60% alcohol and 40% water..

how the systems work here.. it measure the oxygen in the exhaust.. burnt water has lots... pass anything like that..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TrueNorthStar &raquo;</TD></TR><TR><TD CLASS="quote">

I was under the impression that lower octane burns easier and faster. The reason we switch to a higher octane is because the lower octane fuel is more prone to pre-ignition or detonation. You can extract more performance out of a higher octane fuel because you can increase your compression ratio, crank up the boost, advance your timing or what ever it is you need to do to get more hp (depending on setup).

This is why when you run a high compression NA engine or high boost FI engine you must run a higher octane to keep from blowing it up.

Therefore I would imagine that you would get more of a complete burn with less timing advance with a lower octane.

Maybe I am wrong.
</TD></TR></TABLE>

Higer octane does burn complete and more efficently.

i have a straigt through exhaust system just de-catted (kump of wood ad a lump hammer did te job, In the JDM prelude cat pipe also MR2 turbos' you can just smash the element out!)

I run between 100 - 105 octane fuel and Passed last test no problem!

higher octane = cleaner emmisions and more gas miles!

If you ever see Kerosene (aciation fuel) burn it burns blue and you can hardly see the flame. A guy got banned from rallying semi-pro here in england because he tuned his car on the stuff then on one event when the backend slid out and he got stuck, the crowd went to push the car but most had there hands badly burnt because the fuel tank had bust and they couldnt see the blue flicker of the flames on the tailgate!

 

there are so many things wrong with the above posts i dont even know where to start. for one a lot of youre approaches to passing smog were just plain wrong. the plugs, cap and rotor were a good idea, probably what made you pass. however rubbing alcohol is just a bad idea, probably will just make youre car run like crap. advancing the timing will increase NOX, possibly make you fail for that.(not an issue because a 98 ,timing will be up-integrated). removing the air filter will do absolutely nothing except run crap through youre intake. High HC's are caused by a missfire, trying to run the car leaner will just cause higher HC's from a lean missfire, and removing youre air filter will in no way make youre car run leaner. getting the car hot will help, but the smog tech should make sure that the car is hot before smogging it. tight valves will usually not cause a car to fail HC, and if so it will always fail CO too. CO is high when the car runs rich, and with tight valves on a speed density system a car always runs rich. (a 98 should not have adjustable valves). An O2 could definately cause a HC failure due to a lean missfire, 02 will read rich and trim lean. the comment about not getting the car hot because you might be overheating the cat, i dont even know what to say about that. thats really out of left field. replacing the cap, rotor and plugs increasing HC? i dont think so. the octane dispute is really almost irrelevant, not going to make a difference for HC's. The type of gas, (shell, chevron, rotton robbie) can. I have seen bad gas cause failures. lower octane fuel has less iso-octane, more HC's. more usable fuel, but by such a little amount its not going to affect HC's out the tailpipe on a 98 honda. High octane does reduce knocking which will definately cause high NOX, but will not do anything for HC unless the car is knocking. I have used octane booster to try to make a knock not knock and pass for NOX, it did not work. Talking about combustion efficiency, timing and octane..... 14.7 is stoichiometric which is what all car manufacturers are shooting for. it is the A/F ratio that a catalyst works best at, it is what runs the cleanest. the hotroder wants 12.6. Why richer? more HC's, not as efficient but there is more to burn. Fuel goes out the tailpipe, but more fuel is burnt, fuel has a cooling affect, less likely to missfire running rich (more HC's between the electrode on the plug to get ignited). Low octane fuel has more HC's, so on a racecar engineers will run the lowest (leaste diluted by isooctane) octane possible without knocking. obviously there are high pressures and without a high octane they would not be able to run the same pressures (dynamic compression) as they do. but they limit compression to reduce pumping losses. the same sort of losses that result from advancing timing which is why race engines should be designed to run best off minimal spark advance. compression is a big load on a motor, a large power robber. at a certain point compression becomes more of a burdon than a benefit because it takes so much to compress the mixture. when talking about advance, the leaste advance for a complete burn is what you want. every degree that the mixture is ignited before TDC the motor is working against the pressure building in the cylinder. so advance is not always better. So really the lowest octane possible, and the leaste advance for complete combustion is best.