3rd Gen / L98 Engine Tech 1982 - 1992 Engine Related

high amounts of hydrocarbons

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Old May 30, 2003 | 05:07 PM
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Big_Z's Avatar
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Angry high amounts of hydrocarbons

So i just went to get my car emissions tested. here are the results

hydrocarbons: 15.5 standards: 2.0
CO:1.4 standards: 30

They gave me a paper that says high levels of hydrocarbons "result from unburned fuel or excessive evaporative emissions." Why would it not be burning fuel? Could my timing be turned too low? I was fooling with it and turned the timing down quite a bit just because it seems to run a bit better that way, but could i have turned it too low? is there anything else? thanks for helping
Old May 30, 2003 | 06:51 PM
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"Unburned fuel" means you're running rich. It's probably a tuning issue, but setting the timing back to stock should help.
Old May 30, 2003 | 07:57 PM
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well should i take it to a shop then? I dont know anything about tuning the carb. And, I had a knock/popping sound deal/hesitation goin on a bit ago, and someone told me that it was running lean. I got rid of it by turning the timing down. whats the deal?
Old May 30, 2003 | 08:37 PM
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Bring it to a shop i had my Zed in to get the timming done and he timed it and tuned the carb for $10 now it runs better then it ever did

this is what I did to get mine to pass my mods are headers mild cam and no A.I.R pump

I leaned it out a bit
set the timming to 8*
put a cat on_
put an egr valve on_

and she walked right though

_= you might not need to do this
Old May 30, 2003 | 11:13 PM
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my brother im in the exact same boat my car bombed its emission test too and my hydro carbons were higher then theyre allowed to be i think it was 5 something but im in ontario so i have to pass a lot stricter laws. the other thing it can be is if your filters are all clogged up. unburnt fuel can also happen if your engine isnt getting the air it needs
Old May 31, 2003 | 12:04 AM
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hmm, indeed. The air filter is pretty ****ty lookin. Also, I was thinkin, doesnt higher octane gas need high temps to burn right? I have 93 octane in there right now, and the car wasnt really warmed up that well. There was a thing at the test site suggesting to drive 20 minutes at 55 mph to warm up the engine. Also, I beefed up the timing some tonight, it was way retarded from when i was playing with it before i left, so i advanced it back up quite a bit. If I get a new air filter and let it warm up a while y'all think it'll be lookin good?
Old May 31, 2003 | 01:27 PM
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ttt
Old May 31, 2003 | 06:28 PM
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hope so i just have to toss in new spark plugs and then mine will be set to be re tested. add me as a buddy for when you go to do yours retested let me know how it goes and ill do the same maybe whoever goes first can learn something from the other =)
Old May 31, 2003 | 09:29 PM
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I took my car too inspection yesterday and i forgot which gas it was but passing is like 1200 and mine was at 2530 or something like that bastards made me spend 45$ on an inspection sticker from my uncle lol
Old May 31, 2003 | 10:21 PM
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lol yeah i have a friend who told me if i dont pass my e-test next time he has a mechanic who will rig it up for me. this is why you need to know people!
Old Jun 1, 2003 | 05:09 PM
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Sounds like a faulty EGR. Make sure it opening at WOT.
Old Jun 1, 2003 | 09:53 PM
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whats an EGR and how do you check it?
Old Jun 1, 2003 | 10:19 PM
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An EGR= Exhaust Gas Recirculation Valve. It sits right between your Temp switch and your carb or throttle body. It looks like a vacuum booster. It is bolted onto you intake manifold and has a round "spinning top" look to it. IF you start the car and reach underneath it you should feel a diaphragm. If it moves freely up and down then it is still good if it doesn't then you need to replace. Also while you are checking see if your vacuum hose connected to it is working properly. If it isn't sucking then you will have problems. While it is off your engine should run a little fast, as soon as you reconnect the vacuum hose back the engine should return to normal operating speed.
Old Jun 1, 2003 | 10:38 PM
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well if your egr valve is busted your car probably wont sound like its running perfectly. If your car sounds good i bet thats not the problem (although still a good thing to check). The other thing is did you just buy this car? The car i just bought that failed had been sitting around all winter. When i changed my fuel filter today the fuel that came out of the line was almost black. If the fuel in the car is really old that could be enough to make your car fail right there
Old Jun 1, 2003 | 10:55 PM
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well I've had it about a month and run through a couple of tanks of gas, so thats not it. I've been intending on changing the fuel filter, i just dont have any tools so i need to borrow some. If it means anything, it has a bit of a lopey idle, like it has a big cam in it, although i dont know if it does or not. also, there is a hissing going on that sounds like a vacuum leak, but ive been told its normal. but i dunno just yet. I'll take a look at some things tomorrow and get back to this. thanks!

Last edited by Big_Z; Jun 1, 2003 at 10:58 PM.



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