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Tips on passing smog

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PBK522

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Hey everybody.

I've got a 1990 Blazer, fuel injected, 350 gas, with 73k miles. I'm having trouble passing smog. Before I jump i too heavy does anyone have any ideas. I really don't know what makes a car fail smog specifically.

one useful peice of info: I get a puff of white smoke when I first start the car

Any inof would be great.

Thanks
 
puff is valve seals most likly. and this will burn all the time. but when sitting the oil puddles in the motor and when fired it is all buned up in big batch. when is the last time full tune up? and have you changed the fuel filter. the most over looked item of all. when pluging up big loss of power. and check the pcv port on the tbi and see if pluged. thay are small and fill with sludge.
 
Try to find a chevy small block that DOESN'T puff on startup - very common, valve seals, PITA to fix, don't worry about it 'til it smokes like a deisel. Anyway they check HC, CO, and NOx for the test. High HC - hydrocarbons - is usually tune up related (plugs, wires, timing etc). High CO - carbon monoxide - is usually fuel related (too much or not enough). High NOx - Oxides of nitrogen - is the tricky one. That is usually caused by a bad catalytic converter or bad EGR system.
These are just general guidlines and not the absolute truth. Somebody may choose to correct me, but I have found these general rules solve a lot of problems. I did emissions testing for 3 years and repairs for the past 7 so I'm not talking from my nether regions here. Let me know what the results were and I can guide you in the right direction.:)
 
Hey, I just got my 92' gmc with 220,000 miles to pass smog in California (and that was even at a "test only" smog station!). Besides the normal tune up, change your egr valve, O2 sensor, catalytic converter and pcv valve. Also, make sure your timing is set properly (I think it should be at 0 degrees with the distributer disconnected from the computer.). Good luck!!!!!!!!!!!
 
theres already additives in gasoline to clean the fuel system. And octane additives are a waste of money and it also increases HCs in the exhausts.



PaddeyBerk, do you have the HC,CO,CO2, or NOx numbers? It will help narrow down what the issue is with your vehicle.
 
last call for alcohol!

A few bottles of isopropanol dry gas helps lower hydrocarbons and CO readings--I've gotten a lot of "flunkers" to pass by adding 2-3 bottles to a 1/4 tank of gas,and adjusting the timing,leaving the pvc valve hanging out of the valve cover while testing if the motor has some blowby,leaning the carb idle mixture,and increasing idle speed slightly can all haelp you to pass the test--(of course a good tune up and oil change is almost mandatory,a new air filter can make a huge difference too!)then re-set everything back to "normal" where it runs good once you get the sticker...I'm glad my older heaps are exempt..:crazy:
 
A guy i know had the same problem. His pick up had like 280,000 miles on it.He ran it untill the gas tank was almost dry and then he added 2 gallons of Colemans Lanturn fuel to the tank. It passed with flying Colors. I guess that stuff burns real clean.
 
diesel4me said:
A few bottles of isopropanol dry gas helps lower hydrocarbons and CO readings--I've gotten a lot of "flunkers" to pass by adding 2-3 bottles to a 1/4 tank of gas,and adjusting the timing,leaving the pvc valve hanging out of the valve cover while testing if the motor has some blowby,leaning the carb idle mixture,and increasing idle speed slightly can all haelp you to pass the test--(of course a good tune up and oil change is almost mandatory,a new air filter can make a huge difference too!)then re-set everything back to "normal" where it runs good once you get the sticker...I'm glad my older heaps are exempt..:crazy:
Click to expand...

I added the "guarranteed to pass" bottle to my tank then passed. I failed before it then weeks later added it and went straight through!!!! :cool1:
only $6 at your parts store
 
Umm, I dont want to sound lie a smart ass here, but it helps if we know what specifically it fails for. YOu guys are just sayign to try this and that. What does it fail for? Know what I mean?
 
I tried to do the technical approach, but the "dry gas" idea came up. I have seen it work before, but it's like bondo - it just covers it up. If it runs right you will have better gas mileage and a cleaner running engine. Nuff said
 
Your right about the better it runs the cleaner it will burn... but you will get to a point where you won't be able to pass smog, that is, if you built it for performance. Making it smog legal usually translates into about 50 hp loss over the same motor that didn't have to be smog legal. Since alot of these guys built they're rigs for performance it makes more sense to pass it no matter what it takes even if it means cheatin because most likely the higher hp guys wouldn't be able to pass no matter how well it was running... once you get to certain cam sizes, carb/tb sizes, fuel pressure and map you just won't pass...depending on the vehicle.
 
There is a very fine line that is crossed when you build for performance. Some stuff you can get away with, and some stuff you can't. He was talking about a later model fuel injection setup. There is only so much you can do to a compy controlled engine before mister check engine light comes on. He also didn't mention any mods, so therefore I assumed the truck was stock. And I think the whole thing is moot because the original poster hasn't even said what he failed for. We should not assume anything until we know the situation is.
 
Since alot of these guys built they're rigs for performance it makes more sense to pass it no matter what it takes even if it means cheatin because most likely the higher hp guys wouldn't be able to pass no matter how well it was running... once you get to certain cam sizes, carb/tb sizes, fuel pressure and map you just won't pass...depending on the vehicle.
Click to expand...

I was talking about people in general on this site and that posted on this thread.
 
RustyMule said:
There is a very fine line that is crossed when you build for performance. Some stuff you can get away with, and some stuff you can't. He was talking about a later model fuel injection setup. There is only so much you can do to a compy controlled engine before mister check engine light comes on. He also didn't mention any mods, so therefore I assumed the truck was stock. And I think the whole thing is moot because the original poster hasn't even said what he failed for. We should not assume anything until we know the situation is.
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+1


Im still waiting for a response. It can be a bunch of things and theres still no info if there are any codes stored in the ECM.
 
Fierospeeder said:
+1


Im still waiting for a response. It can be a bunch of things and theres still no info if there are any codes stored in the ECM.
Click to expand...

Well not only codes, those wont necessairly help, but where he lives and what the readings are would!!!!
 
one useful peice of info: I get a puff of white smoke when I first start the car

Any info would be great.

Thanks[/QUOTE]

did you guys read at all he said puff of WHITE smoke... not blue as in oil he said WHITE
coolant, that will reck your O2 sensors and stuff that cant be subjected to silicon based products such as coolant and RTV
 
If there was a problem with the cooling system leaking into the combustion chamber in any way, it would not just be on startup and you would KNOW there is a problem. Most likely it would not make any puffs on start-up, but would get worse as it gets warm. If we took a poll on how many people with chevys had a puff of "white" smoke on start-up, the resonse would be overwhelming. It LOOKS white, and the key to coolant smoke is that its very puffy - like a cloud. I had an old p.o.s. with a blown head gasket that laid down a trail of smoke for a hundred yard behind me. I loved it because nobody tailgated me.:grin:
 
blackblazer717 said:
one useful peice of info: I get a puff of white smoke when I first start the car

Any info would be great.

Thanks
Click to expand...

did you guys read at all he said puff of WHITE smoke... not blue as in oil he said WHITE
coolant, that will reck your O2 sensors and stuff that cant be subjected to silicon based products such as coolant and RTV[/QUOTE]

Yes I did, did you read me response? "You prolly killed the cat." White or blue, coolant or oil, regardless, he contaminated the cat.
 
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