A ways back - '89 I think - I had passed an emissions test with the guts knocked out of my cat. It collapsed and got plugged, so I knocked out the internals with a tire iron.

Now that I've got another 2M4 years later, I'm wondering if I can do the same...

RI now uses a treadmill type test rather than a wand up the pipe. Has anyone ever passed a test this way recently?

I've heard of people passing without an operating cat. A properly tuned engine that is running good doesn't need a cat to pass emissions....it won't be putting out high amounts of the bad pollutants...this is what I've heard at least.

Personally, I don't worry about that. We don't have emission testing here. My cat was removed when I replaced the exhaust.

It's tough. Yes, some people have done it but it's not easy at all. You could be tweaking for weeks to pass.

For the price of a new cat and tremendous improvement you get in the emissions, put one on. Take it off later is you must.

I had a Flow Master CAT installed in my car
for $200 about 5 years ago. If you live in
CA watch out for SMOG II requirements. Not
sure if they look underneath the car, but
now they do drive it and if the tech
thinks it's too load, he may take a look.

Depends on where you live. A cat is not a requirement unless they require a visual inspection. A clean running engine can run cleaner without a cat... but people in the gov't and people in the cat business don't want you to know that... Some states do not require a visual test, just the sniffer.

I've passed an emissions test with no cat. Easily.

When I first built my race car it had a bone stock, perfectly running 2.8, with a pretty open exhaust and no cat.

Our emissions test here are on a treadmill with tailpipe sniffers only, no visual test. The limits were 220ppm HC and 1.2% CO, no NOx test. This car passed at about half the legal limit for both catefories.

For comparison, my other V6 Fieros with cats have readings around 5ppm HC and 0.01% CO.

I can't tell a performance difference on a stock Fiero without a cat. I'd recommend that you eventually spend the $50 and replace your dead one. If you have to do an emissions test without it, though, you'll be fine if your car is running properly.

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Doug Chase
Chase Race
Custom roll cage and exhaust fabrication

I guess it all depends on equipment and inspector. Here in FL back in 99 my Formula passed emissions with no cat, disabled EGR and off-road Hypertech chip (low temp stat & disables EGR). The guy even put the mirror under and all. So I guess now I know why the eliminated this silly test here in FL

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Palm Beach Fieros
http://pbfieros.tripod.com

It is very possible to pass an emissions test without a CAT. A while back I installed a rebuilt engine in my 87 Jeep. (BTW, that engine looks amazingly similar to the Iron Duke.) To make a long story short the Jeep easily passed NJ state emissions testing. A sort while after I was replacing the head pipe and noticed that the CAT was completely hollow. The truck passed the tailpipe emissions standards by a wide margin.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://www.turbochargerpower.com/turbo.htm

quote Originally posted by Dennis LaGrua: It is very possible to pass an emissions test without a CAT. A while back I installed a rebuilt engine in my 87 Jeep. (BTW, that engine looks amazingly similar to the Iron Duke.) To make a long story short the Jeep easily passed NJ state emissions testing. A sort while after I was replacing the head pipe and noticed that the CAT was completely hollow. The truck passed the tailpipe emissions standards by a wide margin.

Proving what I have said before that a car with no cat can be made to run cleaner than a car with a cat... Nowadays I think it is more of a cash cow than a true environmental issue.

Thanks guys - We run a treadmill with a visual, but if you get the *ahem* right shop that knows you're a shadetree wrench spinner they'll ease up a bit as it saves them work for the same money so to speak. Unfortunately they test NOx here and NOBODY passes that. To run my '86 Volvo 740 Turbo took three of us - one to "drive", one to move the distributor (evey 10 seconds or so as it self compensates) and myself to remove a vacuum line every 30 seconds or so just to keep it guessing. Pretty sad as making it run like sh!t was the only way to pass the NOx test. Everything else was fine in the first pass.
Now that I think of it, is there a non ECM distributor available for the Duke? I can keep an old school carburated engine running nice and clean!
BTW - that Jeep was probably a Duke. They ran them for a two year period, as well as an AMC version that was almost a dead knockoff. Hmmm.. that was a pretty torquey little motor. Wonder if it's stronger than the Duke in the bottom end?

My Dad passed back in the day by shoving a bunch if steel wool in the exhaust right before driving up to the shop. (he had glas packs on the car and needed to quiet them.) I don't think it helped anyhting but the sound. He said that he could not give the car much gas or it would blow the Steel wool out.

Don't know if it will help now, but it worked back then.

I lived in the crappy LA smog for most of my life, so anything to reduce air pollution overrides a little increase in convenience or horsepower, in my opinion. Now that I live at the beach, I'm even more determined to "to my job."
Off the soap box,
b

You oughta come up here and live in the Central Valley where all the LA smog gets blown to and trapped... I still don't blame it on cars though...

quote Originally posted by Songman: Proving what I have said before that a car with no cat can be made to run cleaner than a car with a cat...

No way. The emissions numbers in my post say the exact opposite.

WA does two tests, one at idle and one at 2500rpm cruise on a dyno. The limits for both tests are 220ppm HC and 1.2% CO.

I looked up the two emissions sheets from my above example and here are the exact numbers:

No cat:

idle HC 60 ppm
idle CO 0.80%

cruise HC 78 ppm
cruise CO 0.75%

With cat:

idle HC 6 ppm
idle CO 0.00%

cruise HC 3 ppm
cruise CO 0.01%

Tell me how this "proves" that a car with no cat can be made to run cleaner than one with a cat. How, exactly, does the cat make the air exiting it dirtier than the air entering it?

No, catalytic converters do work. Modern fuel injected engines in proper tune run pretty clean without catalytic converters. Catalytic converters make them even cleaner.

Doug

A properly combusting engine will produce Nox above legal limits in NJ.

You can pass hydrocarbons and CO though without a cat.

For the purpose of this discussion I wouldn't take any of the "it's possible", "I know of someone that", "One time I passed" as the answer.

If you want to try, feel free, I can't recommend that *anyone* that must pass go down that path.

If you can handle failing several times, sure, give it a shot. If you're curious, give it a shot. If you need to get this thing smogged and back on the road, put the cat on it and make sure the EGR is working. Your odds of passing are low.

I have to admit, I've never heard of a cat increasing the emissions on a car. I think the possibility is about the same as passing without one.

[This message has been edited by TK (edited 11-20-2003).]

I used to work for a guy who repeatedly told me, " you show me a system and I'll show you a way to beat it"
The question: Is it possible to pass state emissions testing without a CAT? I'd say that it is possible by tuning properly as I've done it several times.
Sometimes a properly tuned engine will go right through. Otherwise adding an MSD ignition retarding the timing and adding alcohol to the gasoline can get you there. Will it run cleaner with a CAT? I'd say yes.

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87GT 3.4 Turbo Best 0-60 5.2 seconds
http://www.turbochargerpower.com/turbo.htm

My car used to pass without the cat. Then they started using the dyno style testers where there is actually a load on the engine. I didn't even know the cat. had been hollowed until I replaced it. Then I passed inspection.

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'87 2.8v6 5spd

No. You will still have Nox PPM levels over 2k PPM if you run an alchohol/gasoline mix.

I believe your experiences, but times have changed as far as testing goes.

I have lab data along with real life NJ emissions data.

Alchohol will bring down HC, but if you run off stock ECM settings, the additional heat from running lean on alchohol will actually bring Nox UP. Nox are created as a natural by-product of combustion when cylinder head temps get up over 2500 and nitrogen bond to Ox molecules.

You can pass with a "smog pump", but I don't think that's what he's asking. You can also get down to legal levels in most states for Nox, by unplugging one of the spark plugs in a 4cyl. If you have throttle body injection, you're going to fail HC and CO though.

quote Originally posted by Dennis LaGrua: I used to work for a guy who repeatedly told me, " you show me a system and I'll show you a way to beat it" The question: Is it possible to pass state emissions testing without a CAT? I'd say that it is possible by tuning properly as I've done it several times. Sometimes a properly tuned engine will go right through. Otherwise adding an MSD ignition retarding the timing and adding alcohol to the gasoline can get you there.

Does the turbo help with emissions? The added air make for a cleaner exhaust emission?

I can't imagine. I didn't run my turbo through inspections though.

The "extra air" requires extra fuel so you have the same combustion. Emissions are measured in PPM and percentage. So you should get similar results. Also, in NJ tests, you wouldn't be on the turbo since it's just 30mph in second gear.

The additional heat created from the turbo would up your Nox readings though.

quote Originally posted by RotrexFiero: Does the turbo help with emissions? The added air make for a cleaner exhaust emission?

Passed the pipe sniffer without EGR or CAT on the rollers. Had a brand new O2 sensor literally an hour before I drove in.

Failed spectacularly on visual.

I believe that it would have only taken a couple of miles of driving before the O2 sensor would stop working its full magic powers....

I passed. But the guy could tell that the cat wasn´t functioning properly. No wonder, I had pipe running strait through it.

quote Originally posted by Songman: Depends on where you live. A cat is not a requirement unless they require a visual inspection. A clean running engine can run cleaner without a cat... but people in the gov't and people in the cat business don't want you to know that... Some states do not require a visual test, just the sniffer.

Songman,
Could you explain why a car can run cleaner if the cat is taken off? That would mean the cat was causing higher emissions. This just doesn't make sense.
Only difference I can see would be less back pressure, not emissions.

Songman:

I'd like clarification on that statement also. Being an automotive engineer for the last 20 years, maybe I've overlooked something. I sure could make a handful of money through our suggestion program if I could convince my employer to eliminate $500 cat off each of our vehicles as a cost savings approach.

Please include all your engineering theories supplemented with corresponding chemical equations (please include ppm values) for cat vs. non-cat. I'll split the money with you.

While you're at it, please include your theory on who killed JFK, since we're approaching the 40th anniversary, and it's still an intersting topic.

Let's not go hog wild here. I don't think Songman's comment requires this.

The conversation is about if a cat is needed to pass and we all have stories about passing without a cat, but I don't think even Songman is suggesting we all remove our cats and blissfully assume they will pass the test.

Thanks TK.. What I said is that a well-tuned engine can pass current smog tests without a cat. It's been proven over and over in the hot rod world. Newer cats have been redesigned and are not as restrictive and they also run cleaner than old cats did. Old cats put out fumes that were just as harmful for the ozone as the exhaust fumes they were trying to defeat.

My point is that some states don't care how clean your car actually runs. If the cat is not there it is an automatic fail. To me, that is crazy... If you want a car to run clea, fine... Fail it if it is not clean enough... Not because someone didn't go shell out a money for a mandated product when they could have passed anyway.

quote Originally posted by TK: Let's not go hog wild here. I don't think Songman's comment requires this. .

Require what? He made a comment that made no sense and was asked to explain it. He answered back and clarified his statement.

Songman,
I can see where you're coming from now. Maybe the older cat's did put out some pollutants themselves (as they aged) versus new ones...I wouldn't doubt that for a minute.
And I agree, who cares if you have a cat or not. If you can pass emissions they should let you go...but as always it's a money thing.

To the post above my comment.

I thought it was just enflaming the conversation and I still do. Heading in that direction is of no use.

As far as asking for clarification, I do it all of the time and get asked myself.

I know Turbo Regal folks that pass without a cat. It's not easy, but it can be done.

At the same time, my tuned up 2.8L V6 Fiero blew 200+ without the cat and failed (ok, empty cat. I didn't know it was empty until I replaced it). With the cat: 4/10 HC and very low CO. NOX was not measured.

I am all for a new thread on how to pass without a cat. If someone had access to the analyzer, it would be interesting to see how far we could tweak the code to get the HC and CO in line. I would expect the NOX to be fine if the EGR was working.

[This message has been edited by TK (edited 11-21-2003).]

There are fifty states in the union and they can all establish their own standards for emission testing on autos. There is no requirement that they be the same as the standards the feds establish for new cars. Some states test NOX and some don't. It depends on which pollutant is giving them trouble with the ambient air quality.

I work in an oil refinery and have been involved with reducing NOX on boilers and process heaters. It's well accepted that NOX and CO move in opposite directions. Conditions that favor CO destruction will increase NOX. I'd be very surprised if an automobile without a cat could simultaneously pass CO and NOX. So when claims are made about passing emission testing without a cat, it would be helpful to no what was measured and what the standard is.

P.S. Passing a state test that may only measure CO and hydrocarbon doesn't mean you're legal. If the cat is removed you've violated federal law by virtue of having tampered with the emission system.

Also realize that all emissions are not measured. An emission test is designed to verify whether the system is working properly, not whether every emission output is within spec. I used to be a test engineer, and I designed test systems for electronic assemblies. These assemblies went through an exhaustive battery of test during the design phase, but afterwards, only a small subset of these tests are performed to verify operation. It's the same with emission tests. A subset of the emissions levels are tested, assuming that if they pass, all the others will, too. This does not take into account someone trying to defeat the test. Just because you pass an emission test, it doesn't mean all the emission levels are within spec. Last time I replaced a cat, I was a bit low on funds, so I hollowed it out until I could get it replaced. When I did replace it, I couldn't tell any difference in power or drivability.