What should you do before emissions testing?

I just got a notice in the mail to take my car in for emissions testing. I have no reason to believe my car would fail this test but I was wondering if there was anything relatively simple I can/should do to stack the deck in my favor? Oil change, higher octane gas, engine cleaner, etc…

Dang…I meant this for GQ. I suppose it can live here so I won’t bother a Mod about it but if they feel it needs moving have at it!

Year, make and model of your car please. Mileage too.
General things would be. Change the oil, get rid of any fuel contamanation. New air filter element.

If you have not abused the car it should pass if none of its systems are misfunctioning.
Good luck.

Here’s my anechdotal reply.

I drive beaters. 15 year old cars. They have 100,000+ miles.

I failed a test a few years ago. The guy who tested my car said, "hey, don’t go for repairs. Get your oil changed and bring the car in “hot.”

That’s the best I can tell you. And it has worked for me. Change your oil and filter(cheep) and drive it for 20 min or more on expressway at 55 mph or more. Go immediately to test. It will pass unless you have major problem. Get it as hot as you can.

1999 Chrysler Cirrus, 6-cylinder, 75,000 miles (give or take a few hundred).

I really don’t think the car will fail. It runs just fine, oil changes have been regular throughout its life and so on. I just want to maximize my chances in an easy fashion if I can.

If the sensors are all working correctly, and the catalytic converter is in good shape, then you should pass smog even without changing your oil.

My '79 El Camino passed smog even though I had a bad carbeurator, a bad catalytic converter, misfires, and exhaust leaks. I don’t think you’ll have a problem.

I thought that catalytic converters were a California-only phenomenon.

Am I wrong?

Quite. Catalytic converters have been installed on all US cars since the 1970s. I had a 1971 Chrysler Newport which came with one from the factory, they weren’t mandatory until a few years after that, when leaded gas started to be phased out.

For years people removed them (illegally), however, with the advent of computer controls on cars, that’s become increasingly difficult to and still have the cars run properly. It’s also impossible to get your car through emissions anywhere they do a visual inspection to check for a convertor.

First off look under the hood and see if there is an air pre-heat tube connecting the air cleaner to somewhere near the exhaust manifold. These tubes are often a shinny silver corrugated hose, and sometimes a dark fabric like tube. If your car has one make damn sure that it is not broken, torn, or disconnected. These tubes were the single largest reason for failures on the underhood inspection when I was doing smogs.

Other than that, an oil change can’t hurt. New plugs also can’t hurt. For sure do take the car for a good run on the hiway just before you go to the test station, and leave the car running this will keep the converter up to temp and may help pass a marginal car.

Oh and Tuckerfan, and Mikie converters were installed for the first time in the US for the 1975 model year. Gas stations had to start pumping unleaded fuel during the summer of 1974 so that the '75 cars would have unleaded to run on. Leaded fuel (all that was available in the US in 1971) will kill a converter by coating the substrate with lead in a very short order (like one or two tankfuls) rendering the converter inop. This site gives the first intro date for converters in the US as 1974 which would be a 1975 MY car. Also a check of this site shows no replacement converters listed for any car before 1975 MY.

Rick, you’re right about leaded gas killing a cat. Still, my Chrysler had one on it. Which is odd, now that I think about it, because it was designed to run on leaded gas, but it also had the underhood sticker stating it was catalytic equipped. Perhaps my grandfather got suckered sometime in the 1970s (when he owned the car) into installing one. I know that when I owned the car and had to have the exhaust system replaced, the mechanic mentioned not putting on a replacement cat since it wasn’t legally required for the car. Which I instantly regretted not doing since the engine was significantly louder without the cat. (Before, with the cat installed, you could turn the car on, and not hear the engine. Coolest thing in the world was driving that beast late at night with the windows rolled down, and the only sounds you’d hear were the tires on the road and some wind noise.)

Since this is IMHO, I’ll ditto the remark about the engine and all components being ‘hot’.

And I’ll ditto it again. I drive a 23-year old car, and I just warmed it up by spending about 15 minutes on I-25 and I-40, then just drove it where I was going to test it. It passed really, really well.

I’ve heard that drinking a ton of water and vitamin B will often fool the emissions test.

Glad I wasn’t the only one thinking that.

And stay away from Mexican food.

I am having to do the same next week. The first thing to do is nothing. Do not spend a dime on the car. Most states require vehicles that fail an emission test to have a certain monetary amount of repairs done to either pass the test or receive an exemption. Any money spent prior to the initial test does not count towards this amount. If your vehicle fails the test, then spend the money on filters and an oil change. The only money you should consider prior to the test would be for any exhaust system repairs. An exhaust leak may disqualify a vehicle before the test is even given.

Make sure that your vehicle is at full operation temperature prior to the test. A 15 minute drive on a freeway is recommended to ensure the engine is at full operating temperature and to burn off some of the gunk that can build up in cars that are used for around town driving. Use the same fuel that you always use. Some folks believe that a tank of higher grade gas will help, it usually makes the test come out worst.

Check out your state’s website. There will be more info there.

ah… i’d suggest beano.