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Can anybody give me tips to pass emissions?

T

Tuff84blaze

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I've been talking my brother into getting a k-5 or suburban for years now, and he finally broke down and got a 1990 v2500 suburban the other day. long story short he took it to emissions today and the thing failed the Hydrocarbon test at Idle it blew 411(ppm) and the limt was 400 /forums/images/graemlins/crazy.gif.
Oh yeah it is the original 350 with all the orignal smog equipment intack and over 180,000 miles and it runs perfect.

Thanks for your time and help in advance
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Change the oil, O2 sensor, and spark plugs, set the timing and go back. You'll pass with flying colors.
 
I hate to say it but I agree with Tim. /forums/images/graemlins/doah.gif /forums/images/graemlins/histerical.gif /forums/images/graemlins/histerical.gifAlso make sure you are good and warm when ya go in to get it emished. Umm the truck not you warm. /forums/images/graemlins/thinking.gif

Good luck to y'all in the future.

Allan
 
If I remember correctly, excess hydrocarbons means it has unburnt fuel. So as previously mentioned, change the spark plugs and give it a tune-up. Also have the engine at normal operating temp -- drive it around for 20 mins or so. You may also want to get it 'pre-tested' just so it doesn't get labeled as a gross polluter.
 
I was always under the assumption the when the hydros was high, it usually meant that the cat was bad. Hydro's is unburnt fuel, the cat is suppose to burn the unburnt fuel out.
 
I had trouble getting my blazer to pass emissions also. Stupid emissions test. I took my rig to Tunetech. They do some pretty bad ass work. They changed a rod in my carb, and it passed. I've heard that you can put a bottle of something called "heat" into your gas tank once your tank is really low, and it will help you pass. Don't know if it works, just something i heard.
 
I've also heard that you can detune the motor to the lean end to the point that it almost doesn't run and even heard of folks puttin some isoprpyl alcohol in the tank. I'm sure there is some cool smart mechanic guy that know a nifty trick that none of the rest of us are aware of.

Good luck to ya in the future.

Allan
 
I wouldn't be suprised if the stock cat is plugged or not functioning properly. With 180,000 miles that is a lot for an original cat.
 
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I wouldn't be suprised if the stock cat is plugged or not functioning properly. With 180,000 miles that is a lot for an original cat.

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Catalytic converters are designed to last the life of a vehicle. Unless they die from corrosion or an overly rich fuel mixture burns them out or plugs them up, they should last indefinitely.

If you lean out your fuel mixture your spark plugs will have a hard time igniting it all and you'll have an intermittant misfire which will probably be enough to make you fail emissions.

My friend had that idea with his Camaro and failed. I tuned it to run correctly and retarded the timing to 4* and it passed with flying colors.
 
Not trying to be a farthead, but i heard somewhere that the "average" life of a vehicle is around 15 years?
Mind you thats an average.

I also do recall hearing somewhere awhile back that the cats usually only last up to about 150-200k miles. Even running clean, it's still gonna get carbon build up inside.
Anyhoo, i dunno for sure, mine has 211kmiles and is still using the original cat, i will find out in the next couple of weeks wether it passes emissions or not. tags are due /forums/images/graemlins/rolleyes.gif
 
Like I said, an overly lean fuel mixture can easily destroy a cat.

I have no doubts that cats sometimes need replacment.

It just seems that people are quick to blame the cat only to find out later that wasn't the problem. Trouble is many times a vehicle will pass emissions with a fresh cat even if it has other problems so the real issue never does get fixed.

I have no doubts that converter woes are a possiblity, I'm just saying, try the cheap stuff first!!
 
I come from the world of no computers but less gas to begin with less on the way out. Spark make combustibles in the chamber go boom whether lean or rich. Too rich to much combustibles in the chamber to burn cleanly. Too lean not enough to make power.

I've been wrong in the past and it might happen once more in the future. /forums/images/graemlins/yikes.gif

Good luck to y'all in the future.

Allan
 
Hell i agree with ya, do the normal tune up first, it's best to have new stuff on there anyways. I also remember i had a car awhile bask i found out had a hollowed out cat, i never could get that thing to pass emissions unless someone tweeked the timing, left off a vacuum hose and messed with the air/fuel mixture, then it was just barely that it passed. Anyhoo, he's had some good ideas as what to do, good luck with it, we can only tell you so much to do with it, it's kind odd that a '90 would not pass emissions though, something is definately not right.
Are all plugs firing? thats something else i was just thinkin, if it has a miss, or a half ass firing spark plug, it will not burn all fuel. But then again that goes into the catagory of changing the plugs /forums/images/graemlins/doah.gif
Oh well, good luck with it.
 
I would have to agree too with changing the O2 sensor, and a tune up as well. When the exhaust manifold O2 sensor goes bad, on a computer-controlled vehicle, the vehicle is often stuck in what is called "Open Loop", which will cause a rich fuel mixture condition. Open Loop, on a computer-controlled vehicle, is the equivalent of a choke on a carbureted vehicle. It makes the engine fuel mixture rich when the engine is cold, until it warms up, and then the O2 sensor starts to work and go into "Closed Loop", which is when the computer takes over and starts controlling the fuel mixture. A dead cat converter can cuase problems as well. When an O2 sensor goes bad, and the engine runs rich the cat can become clogged. If the truck exhaust system sounds like it is weasing, then the cat could be causing a problem too.
 
I kinda agree, but the other thing is if the O2 sensor goes bad, it "usually" triggers the check engine light. Forgot to ask about, is the check engine light on?
 
I remember when I graduated from the Arizona Automotive Institute, in the late 70's early 80's, and they where teaching us about the new-fangled computer systems that where starting to com out on cars. All the books and teachers said that if there where a problem with the engine a "Check Engine" light would come on and the computer would store a trouble code. "In a pigs eye, and a perfect world". After a lot of years as a mechanic, I cannot tell you how many times a computer input device has gone bad, and the computer "Check Engine" light did not come on, and there was no trouble code stored. I had to troubleshoot the problem the old fashion way "Can you say "Ohm Meter.""
 
Drain the gas tank,Get a gallon of low Octane gas and buy 2 gallons of coleman Lanturn fuel- mix them together. make sure the motor is nice and warm when you get there......
 
I have an 89......make sure you have a 195* thermostat....Delco 02 (NOT a bosch)....those two lessons cost me about &150 extra.... /forums/images/graemlins/thumb.gif
 
Im not trying to steal the post but My 88 just failed HC today during its 15&25 mph test. It blew 146 and 136. It was good and warm. The old owner told me he thought the cat was going bad and was suprised he was able to smog it when he sold it to me (my HC numbers are 3 times last years levels when I bought the truck and the NO was 2 times /forums/images/graemlins/eek.gif) Said it probably had 200K+ miles on the cat. Think maybe should start there. /forums/images/graemlins/thinking.gif
 
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I kinda agree, but the other thing is if the O2 sensor goes bad, it "usually" triggers the check engine light. Forgot to ask about, is the check engine light on?

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That isn't necessarily true. OBD I is very stupid. It is possible to have a horrible cat, and no check engine light.
 
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