03-01-2010, 11:57 PM | #1 |
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Won't pass smog.
79 chevy won't pass smog. It's been sitting for two years. I changed plugs gas oil and it runs better than ever. It's never not passed but now it's a problem. Any ideas on where to start?
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03-02-2010, 12:18 AM | #2 |
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Re: Won't pass smog.
Not sure if I can help, but it would help to know what it actually failed on. The term "Smog" is kind of generic as they look for specific things and it only takes one of them out of range to fail. Did they give you a printout or readout showing why you failed.
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03-02-2010, 12:53 AM | #3 |
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Re: Won't pass smog.
Yea, more info is needed.
Was the cat hot? Were you using the highest octane fuel you could buy? If the truck was parked for two years, you need to run it. Carbon buildup on the valves and exhaust pipe will hurt readings. Was the failure at low RPM, idle or high RPM? What emission equipment is on it? |
03-02-2010, 01:03 AM | #4 |
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Re: Won't pass smog.
Engine was driven all morning on the highway. I did not put high octane in.
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03-02-2010, 01:04 AM | #5 |
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Re: Won't pass smog.
Failed on idle and high speed co output.
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03-02-2010, 01:08 AM | #6 |
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Re: Won't pass smog.
I was going to fill her up with some higher grade fuel what do you sugg? To help clean out the bad stuff
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03-02-2010, 01:52 AM | #7 |
BAD BOW-Silverado XST
Join Date: May 2000
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Re: Won't pass smog.
First, run a can of Sea Foam through it. You can buy it at any parts stores.
What is your timing? Can you post the numbers between passing and failing? Is there a big gap? Do you know how to adjust a carb? You could run it a little lean to pass. Read this on using a vacuum gauge: http://www.centuryperformance.com/tu...e-spg-148.html |
03-02-2010, 11:26 PM | #8 |
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Re: Won't pass smog.
if it where me 1 i would change cap rotor. 2 change spark plugs and the wires. 3 new pcv valve. 4 change the oil. 5 set the ildle to 1500 rpms and drip water in the carb so that all the carbon blows out the pipe redneck cleaning. 6 put 93 oct in with a bottle of octain boost and run the piss out of it till it runs out of gas fill it back up and go streight to the smog test it will pass with flying colors hehehehe.. what i've always done never had a problem
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03-03-2010, 12:40 PM | #9 |
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Re: Won't pass smog.
Had a straight-six Nova with the same issue and all of the items already posted are dead-on, and the only thing I'd add is to use Valvoline racing oil - heaviest grade you can find. That's what I did and squeaked by.
Well, that and the 50-dollar bill I slipped the guy. (oh wait - did I say that out-loud? Mac.
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03-03-2010, 05:26 PM | #10 | |
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Re: Won't pass smog.
Quote:
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03-03-2010, 05:28 PM | #11 |
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Re: Won't pass smog.
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