need help understanding why it didnt pass smog???HC (ppm)??? any help

[mario]

Hey cb7 tuners, I am in a little problem right now i took my 91 accord to pass smog and it failed i don't understand the paper if u could help me out ill gladly appreciate it well it failed in HC (ppm) MAX 120 and MEAS 135 FAILED and the gas cap visual???? OK i know the gas cap, but HC? i am guessing that it needs more or less twitching with the idle i put in back on time ~15º BTDC if i am correct i just need help understanding what HC (ppm) max and MEAS mean??? any help tuners it will be gladly appreciated i barely bought the car runs great just gotta learn the language lol...

[PakaloloHonda]

Google is a Real Friend ..

http://www.smogtips.com/failed-high-hydrocarbons-HC.cfm
When's the last time you changed your cat?

[mario]

i haven't i barely bought the car like a week ago. could it be the cat? the smog technician said i barely failed i would like to know by how much? or how much does a good accord would give in the HC (ppm) MAX and MEAS? from there i think i would know what way to go

i haven't i barely bought the car like a week ago. could it be the cat? the smog technician said i barely failed i would like to know by how much? or how much does a good accord would give in the HC (ppm) MAX and MEAS? from there i think i would know what way to go

thanks for the web site i barely saw it thanks.

Thanks ima look into it

[dj_ender]

I had the same issue when I bought my cb, it ended up being a cracked header, more exactly, a severed runner. And the tech told me that just changing your oil can help, because the gases they test for can get trapped in the oil.

[alan lx]

It sounds like it barely failed. I would simply retard the timing and just make sure the engine is at operating temperature and it should pass. Retarding the timing should get it passed. Then you can put it back where it was. There are shops in my area charging $80.00 and up to do this. It takes 10 minutes tops. From what i am hearing, there are so many people doing what i just described that emissions testing is a joke because so many people are "working around it". Best of luck.

[wed3k]

we need more info. measurements on all the gases and is that off idle or idle?

[ferenza]

Hey cb7 tuners, I am in a little problem right now i took my 91 accord to pass smog and it failed i don't understand the paper if u could help me out ill gladly appreciate it well it failed in HC (ppm) MAX 120 and MEAS 135 FAILED and the gas cap visual???? OK i know the gas cap, but HC? i am guessing that it needs more or less twitching with the idle i put in back on time ~15º BTDC if i am correct i just need help understanding what HC (ppm) max and MEAS mean??? any help tuners it will be gladly appreciated i barely bought the car runs great just gotta learn the language lol...

OK.....
HC =(Hydrocarbons)
ppm =( parts per million)
Hydrocarbons is unburnt fuel coming out of your tailpipe. Since our cars are obd1 and not obd2 we will not get a check engine light for any of this stuff until its too late. anyways to bring down your HC try doing a little maintenece on your ignition system.not enough spark will not ignite all the fuel and cause higher than normal HC. if you havent already change your sparks , wires, cap and rotor,air filter,etc. you are only off by 15ppm so its not so much of a big deal just your cb needs some tlc.

[accordztech]

It sounds like it barely failed. I would simply retard the timing and just make sure the engine is at operating temperature and it should pass. Retarding the timing should get it passed. Then you can put it back where it was. There are shops in my area charging $80.00 and up to do this. It takes 10 minutes tops. From what i am hearing, there are so many people doing what i just described that emissions testing is a joke because so many people are "working around it". Best of luck.

Retard timing would cause the HC to go up.

OK.....
HC =(Hydrocarbons)
ppm =( parts per million)
Hydrocarbons is unburnt fuel coming out of your tailpipe. Since our cars are obd1 and not obd2 we will not get a check engine light for any of this stuff until its too late. anyways to bring down your HC try doing a little maintenece on your ignition system.not enough spark will not ignite all the fuel and cause higher than normal HC. if you havent already change your sparks , wires, cap and rotor,air filter,etc. you are only off by 15ppm so its not so much of a big deal just your cb needs some tlc.

Yes good advice. A good tune up will be nice.

Many people would say its your CAT, but the other numbers on your smog report will help diagnose it.

[SanJoCaF22DrAcc]

I say a full tune up, ( oil filter, oil, pcv, plugs, cap, rotor, fuel filter, and air filter) 91 octane and a bottle of Clean Power if you can find one. @ the gas station pour the clean power in and then fill the tank 1\2 way or about 7 to 8 gallons. Then drive the car around till you have about 1/4 tank. Bring the car to the smog station after a freeway run and try to get it tested as soon as possible. Should pass no problemo.

[mario]

Retard timing would cause the HC to go up.



Yes good advice. A good tune up will be nice.

Many people would say its your CAT, but the other numbers on your smog report will help diagnose it.

yeah your right a tune-up might doin it, it wouldnt hurt thanks advices are well taken in my book

[batever]

my understanding is that a high HC test does not mean your cat is bad, but it can CAUSE a bad cat.

the catalytic converter is to reduce carbon monoxide in the exhaust. Excessive HC (unburnt fuel) going through the cat can cause excessive temps at the cat (causing melting that reduces airflow through the cat) because they can re-ignite at the cat (it gets hot, i'm guessing because of the heat from the catalytic reactions going on within it, but take that with a grain of salt because chemistry is not my strong suit) and also fouling of the catalytic surfaces inside the catalytic converter, eventually requiring you to put a new catalytic converter on.

However, your tests don't indicate excessive CO. AND your reading of 135 ppm vs 120 ppm max is not a lot of HC in the first place; you are just like 12% over the limit and remember that's 135 parts PER MILLION that you are blowing, so not much in absolute terms, but enough to fail smog. . Still, you'd like to knock that number way down.

Though if you included those numbers we could give you comparison numbers on the CO, which could help indicate the status or health of your catalytic converter.

Typically on my car it is extremely low. , like 1/10 of what the legal limit is. (from memory).

I agree that high HC indicates unburnt fuel and your focus should be on the ignition system. It's also possible that once you get done with a new cap and rotor and new plugs (and if the new plugs don't work, new spark plug leads as well, or simply have them tested for resistance to see if they are still good) that you could have a bad 02 sensor. BUT start with the simple and obvious and work your way down. I'm guessing just the new plugs and cap and rotor (not even spark plug leads) will take the numbers back down.

[accordztech]

I say a full tune up, ( oil filter, oil, pcv, plugs, cap, rotor, fuel filter, and air filter) 91 octane and a bottle of Clean Power if you can find one. @ the gas station pour the clean power in and then fill the tank 1\2 way or about 7 to 8 gallons. Then drive the car around till you have about 1/4 tank. Bring the car to the smog station after a freeway run and try to get it tested as soon as possible. Should pass no problemo.

91 octane can potentially cause more HC cause its more unburnt fuel. 91 octane in our cars doesnt burn right. Basically the number indicates its ability to resist knocking. A higher compression ratio will burn 91 octane efficiently. However with our lower compression motors, 91 octane wont be burnt all the way, causing more HC's

[batever]

91 octane can potentially cause more HC cause its more unburnt fuel. 91 octane in our cars doesnt burn right. Basically the number indicates its ability to resist knocking. A higher compression ratio will burn 91 octane efficiently. However with our lower compression motors, 91 octane wont be burnt all the way, causing more HC's

I'm not so sure about that. (i mean, "i'm not sure", not "you're wrong.") I would think that it's possible that a 91 blend would have slightly more HC in it than an 87 blend, but that it's also possible that it could have less. The octane index only indicates the temperature and pressure that the fuel vapor will spontaneously ignite at. Higher octane fuel doesn't necessarily have more HCs in it, but just a different mix that has a higher ignition temperature for a given relative gas pressure. (compression, in our case). The amount of HC may vary slightly because of the mix of HCs used to attain that flashover point but I don't know that it's necessarily a higher amount of fuel value or HC content in the fuel, it just has a higher flash point.

BUT my point is that after the gas/air mixture is sparked by the spark plug, whatever the octane number, the mixture is going to ignite and I don't think having a higher octane number will mean more unburnt fuel.

SOMETIMES higher octane gas mixtures also have better detergents in them and can help clean out the engine, which is a different matter altogether.

I do agree that I don't see how putting 91 octane in is going to help (or hinder, actually) the HC reading at the exhaust. I think replacing ignition components (plugs, dist.cap and rotor, and possibly the spark plug leads) is the way to go and the fue loctane issue is basically a nonfactor for this problem.


interesting factoid: the reference compound for 0 octane is heptane. Of all the hydrocarbons it has the lowest ignition point (in a heptane/air mixture) at a given atmospheric pressure. That temperature/pressure combination counts as 0 octane.

Back in the day, turpentine was distilled from pine branches using stills. Out west, occasionally a still would blow up out of the blue.

It turns out that the Jeffrey Pine, a subspecies in the western US, produces small amounts of heptane. When the turpentine distillers put Jeffrey pine in their turpentine stills, the stills would blow up because of the heptane in the Jeffrey pine boughs.

[batever]

Since you probably get one free re-try on the inspection, and if your spark plug leads are old (say, more than 5 years) I'd replace the spark plug leads as well. It can't hurt, and if they are a factor then you just saved yourself the cost of another inspection, which will take care of a good part of the cost of the leads.

I use Bosch on my car, they are cheaper than the original Honda ones and they work fine.

[darkfusion42]

I'm gonna add that a high HC could also indicate a dirty or bad egr valve....if its not recirculating the exhaust gases that have unburnt fuel in them, then obviously the purpose (to reburn the unburnt fuel) would not be happening efficiently, causing the same result.

run some seafoam. clean out your egr valve. should be good to go.