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Old 06-02-2004, 11:41 AM   #16
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Re: Reducing Hydrocarbons (HC)

Check your compression. You should have about 160 if it is close to perfect. If it is lower, use regular unleaded. The octane of a fuel only increases power if you can copress it enough. You can't run nitro methane like top fuel cars b/c you don't have a 26:1 compression ratio. You only need to replace the cat if it is clogged. Catalysts don't go bad. You're better off just running 87 so you get a complete burn. Let your engine get warm too.
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Old 06-02-2004, 02:11 PM   #17
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fuel with greater octane burns slower ( i think i know what im saying )
some say that the higher the octane the easier u can pass smog.
Others say to just run the car for an hour or so on a full tank. I think the purpose of running the car is to make the emissions flow well. After that u can check it urself by checking if the emisions dont sting ur eyes that much, and u can always check if the gas cap is good just in case although i doubt its bad, and then take it to smog check.
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Old 06-02-2004, 04:17 PM   #18
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Re: Re: Reducing Hydrocarbons (HC)

Quote:
Originally Posted by theDRIFTER
Can any one other than this jacka$$(logik23) answer my other question about the fuel? How likely is it that the cat would make that big of difference?
So I'm a jackass cause you couldn't even read the other posts before posting yourself?
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Old 06-02-2004, 08:51 PM   #19
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Re: Reducing Hydrocarbons (HC)

the engine of my friend's misfires. Also it fail emission cuz by the HC ppm. To fix that, replace spark plugs? IT helps the misfires and might pass emission right??
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Old 06-03-2004, 10:33 PM   #20
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Re: Reducing Hydrocarbons (HC)

Quote:
Originally Posted by johnnyboy5
fuel with greater octane burns slower ( i think i know what im saying )
some say that the higher the octane the easier u can pass smog.
Others say to just run the car for an hour or so on a full tank. I think the purpose of running the car is to make the emissions flow well. After that u can check it urself by checking if the emisions dont sting ur eyes that much, and u can always check if the gas cap is good just in case although i doubt its bad, and then take it to smog check.

lol if emissions dont sting your eyes......i wonder how many kids went and stuck there eyes in front of there muffler pipe to see if it stung or not whahhahahhaahhahaahah.
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Old 06-03-2004, 10:33 PM   #21
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Replacing spark plugs wwill only change something if there's something wrong with the one syou have now.
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Old 06-04-2004, 08:14 AM   #22
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Re: Reducing Hydrocarbons (HC)

OK, I know I'm gonna get slapped by logik23 for this one, my cat is clean, but another solution recommended was to advance the timing... when I took the car into do the smog, my timing was at 18BTDC, since the car is supposed to be at 20BTDC, is 18 retarded, or advanced? Do I want to set it back to 20, what do you guys recommend?
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Old 06-04-2004, 08:57 AM   #23
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I won't slap no one, but get timing gears, or else ask a shop.
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Old 06-04-2004, 11:43 AM   #24
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Re: Reducing Hydrocarbons (HC)

Yes a cat makes that big of a difference. A huge dirrerence. They do wear out. They usually start going downhill after 100k or so. Replace it. It's the best thing you can do assuming your engine is running fine.

Lower octane should help you pass emissions easier. Octane ratings measure resistance to burning. Higher octane is harder to burn and pollutes more. (this is if it's higher than recommended. ie:if your manual sais 87, use 87, if it sais 91, use 91) Lower actane than needed could cause ignition retardation and also cause emissions problems. So unless you're running forced induction or higher compression use what the manual sais.

You also definetly want to make sure your ignition system is in good shape. Poor spark (from bad cap, wires, plugs etc...) causes unburnt fuel. Not only will that ruin your emissions in the short run, it will also wreck your cat.

Warming the engine is a good idea. Rev it up a little bit before you go in. You want the cat hot to burn up any left over fuel or other emissions. (ok, it doesn't "burn" everything, but it has to be hot to work). Also, metal expands when hot so a warmer engine will help any compression problems you may have.

Sorry, I don't know the answer to your timing question.

And, remember, emissions are more than just being allowed to drive on the road. I live in MN where we don't have emissions anymore. When we had them we had great air quality. We got rid of them and now were all breathing nasty crap all day. So don't go with quick fixes, respect the environment.
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Old 06-04-2004, 12:07 PM   #25
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Re: Reducing Hydrocarbons (HC)

Can anyone tell me the diameter of a stock cat converter on a 1990 240sx SE?
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Old 06-04-2004, 02:34 PM   #26
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Re: Reducing Hydrocarbons (HC)

go measure it...im not sure otherwise. so with the octane stuff, is 87 higher than 91, cuz people always say, use 91 it burns cleaner blah blah blah... cuz by what you were saying, i thought that the higher it was, the worse it burned. im so confuzed now.
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Old 06-04-2004, 06:53 PM   #27
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Re: Reducing Hydrocarbons (HC)

When i say higher and lower I mean numerically. As in 91 is a higher octane rating than 87. This means 91 has a higher resistance to burning and there fore needs more compression or forced induction to burn fully. (a good spark helps a lot too) Higher octane fuel is harder to burn. You used to be able to get much higher octane (94, 95 etc...) at the pump. This allowed for higher compression engines and thus more power, but common octane levels were lowered (87 being most common) to reduce emissions. So lower octane is definetly better for the environment, just not as good for building high performance engines. That's why race cars use HIGH octane gas. Clear? I hope so........I'm not always the best at explaining things.

I'll make it simple.
The higher the number, the harder to burn, the worse for the environment.
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Old 06-04-2004, 07:12 PM   #28
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Re: Reducing Hydrocarbons (HC)

all clear
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Old 06-04-2004, 08:14 PM   #29
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Re: Reducing Hydrocarbons (HC)

about the 20 btdc and it being retarded...it is better if you had it retarded which reduces hcc and nox...advancing will increase them both.
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Old 06-06-2004, 01:39 PM   #30
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Re: Re: Reducing Hydrocarbons (HC)

Quote:
Originally Posted by musicsurfman
Hc's Are A Caused By Running Rich, Fuel Pooling, And Clogged Cat's While Running Rich.
Some Methods To Cure This Are: Advance Timing A Few Degrees, Tune Fuel Properly, Check For Injector Clogs, Replace Cat, Run Alcohol In The Fuel System (leans Fuel Mixture And Raises Octane), Up The Boost (if You Have A Turbo Car).
I'm very confused? which one is it... if I want to lower my HC's do I want to advance or retard my timing... right now it's set at 18 BTDC, what do I want it set to, and how do I do it?
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