How can you tell if your Cat is Bad

jlpatton

jlpatton

Daily Driver
:help: During my smog test my HC is way to high 1500 and CO is 3.5 I can adjust the idle mixture down to just 1/2 turn open then the CO is .9 but the HC is still 1500 needs to be > 220 and CO >2. Last year when I got the X and ran it thru the test my levels were HC 100 and .1 Timing is right on no air leaks ran a couple of cans of carb cleaner thru it help a first but just can back up again.
 
Lots of stuff in the archives on this issue.

Go take a peek. You will see many very bad people recommending that you use a mixture of alcohol and gas on the day of your emissions test.

Here is an example of the info:
http://www.network54.com/Forum/12159/message/1136961355/mixture...

Do some reading and see what you think. Both of my Xs are smog exempt here in Missouri, so I haven't had to try this.
 
You beat me to it. I was gonna say "When she coughs up a fur ball on your bed then pisses on you when you sleep" Yes I HAD a cat that did this. She was quite pissed at me.....literally. Notice I say HAD.

Wish I had something useful to add to the thread....sorry.
 
Oh Mister Decker...

Now that is just mean, "Bad People" Come on.

I had my 87 just miss on the emissions test, I ran the gas down low in the tank, then put 2 gallons of Methonal in the tank. Had my wife drive it real easy to the E test, it passed, then had her fill it up on the way home with 87 octane gas. After 20 years or latter than 1987 cars are exempt. It was the last E test for the 87 and why put the aggravation into something that does not matter.

As for the other fellow in the this thread, sounds like the converter isn't up to what it once was. Either change it or mix your own fuel.

Your choice.

TonyK.

Grimsby Ontario Canada.
 
Mr. Decker?

Has my dad started posting here?

I see I forgot my smiley at the end of that sentence. At least I toned it down, I started out with "evil environment rapers". ;)
 
you can tell its bad cause it hasnt left the car yet... sorry no smog tests in minnesota...:woot:
 
What was your NOx?

The things that reduce HC and CO (higher compression, timing advance, fast efficient hot combustion) tend to increase NOx... so to some extent you can trade the one off against the other.

For example, non-cat US-spec 1300s controlled NOx by running lower compression ratios than European and retarding the timing under low-load conditions (the infamous vacuum retard). That reduces combustion chamber tempoeratures so less NOx was produced - but also slowed combustion so the fuel didn't burn as completely, pushing HC and CO up and reducing overall fuel efficiency. So they added the smog pum to pump air into the exhaust manifold to burn the excess CO and NOx.

So:
1) It is possible that advancing the timing to the edge of detonation with the highest octane pump gas you can find will get your HC and CO under control. NOx will go up. If the smog inspector won't accept this setting, it's not helpful.

2) Chances are still fairly good that your cat is dead.

3) I've never tried the alcohol trick, but it sure sounds like something that should work.

4) Defeating the smog controls on an older carbed car is not nearly as evil and anti-social and environmentally destructive as cheating with a newer car. Modern computer control seeks to burn the fuel as efficiently as possible, all the way to H2O and CO2, and messing with this is just going to make things worse. The Rube Goldberg stuff on older cars burns fuel less efficiently to control NOx, so ends up hurting fuel efficiency - and as far as global warming/carbon footprint is concerned, it's the total fuel consumption that matters.
 
EricH said:
4) Defeating the smog controls on an older carbed car is not nearly as evil and anti-social and environmentally destructive as cheating with a newer car. Modern computer control seeks to burn the fuel as efficiently as possible, all the way to H2O and CO2, and messing with this is just going to make things worse. The Rube Goldberg stuff on older cars burns fuel less efficiently to control NOx, so ends up hurting fuel efficiency - and as far as global warming/carbon footprint is concerned, it's the total fuel consumption that matters.
Click to expand...

Also how many older carbed cars are actually on the road? I don't think enough to make much of a difference even if they all had the emissions removed.
 
Mr. Patton...

Forgive me, 'cause its been soooo long... but I believe there is one componant that the CAT really impacts on the test, and I think its NOX.

Even running pure alcohol may not help... Sorry, I can't remember exactly which componanat it was. Why not ask the tester to PRETEST the car for ya or give ya a free RETEST. Then post the figures here and we can help ya better. It may take two trips, but I don't know of any other way to effectively test a CAT.

SECONDLY... Summit STILL sells a universal CAT for less than 60 bucks. There are a couple of ways to install it rather easily... with slip fittings and clamps, welding, or cutting off the flanges from the OLD CAT and welding them on the new ones.

Do make sure the engine is well warmed up, ya got a new air filter, plugs and all controls are OPERATING, which essectially takes them OUT of the circuit and except for the GULP valve and CAT, the engine is running LIKE one WITHOUT any smog controls.
 
When it catches on Fire....

:dance:

ygugyu.jpg
 
Ignition miss?...

If you lean the mixture and the HC does not change (as you stated) then I would suspect an ignition miss of some sort... bad plug maybe. 1500 is quite high... I've had carb'd cars with absolutely no emission controls and HC measured less than 1000...

Probably the most common failure mode for a cat. is a rich mixture (or spark miss) that causes a lot of poorly burned fuel to enter the cat. It then will run very hot as it attempts to complete combustion and eventually the internals melt.
 
mixture is

Not even 1/4 turn out HC is still at 1200 but CO is at .300. Going to try and put on the Orginal Carb 28/30 right now it has a 34 DAT
 
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This sounds right to me, one would assume your talking about idle since you included the idle mixture adjustment. If the engine is running well has a relatively smooth idle and seeing the Co numbers I would look for a vacuum leak as part of my course of action. Lean mixtures can spike the HC readings. Advanced timing is one to look at. If you have an smog pump I would wonder if the air is being delivered to the manifold. Its not an easy thing to diag over the net.

"High HC emissions are caused by only one thing, incomplete combustion, this could be due to an engine misfire, an intake air system leak, a burned valve or low cylinder compression on any of the cylinders.
What this means is that the engine is not burning all of the fuel in the combustion chamber and expels most of the fuel out of the tailpipe without converting it into CO, which means there is a problem with one or more of the cylinders.
It could be simply a bad spark plug or spark plug wire or a loss of engine compression in one or more of the cylinders, I recommend having the basic engine functions checked for a misfire condition"
 
Finaly pass Smog

:dance:I put on the 28/30 DAT carb still no smog equipment attached beside the carbon trap here are the results HC 86 (allowed 220) CO 0.1125 (allowed 2):eyepop:. So I think that I'll keep the smaller Carb on for now and sell the 34 DAT for now.
 
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