what can cause my car to fail an Emissions Test?

Question

i drive a not so great car. and i dont want it to fail the emissions test. what do they look for? and what i do i have to check on before the test?

Answer 1

An old gas cap can cause an older car to fail emissions test, but they are simple to replace if need be, and like someone else wrote, if you fail (like due to old gas cap) then you would be able to go get new one and go back to the same check place and no cost to retest in 24 hrs.

Answer 2

Failing an emissions test means your engine isn't burning the fuel efficiently. If you perform normal maintenance on your car, changing the oil, spark plugs, air cleaner, etc, you shouldn't have to do anything special to pass the test. An older car has a better chance of failing, since some of the parts like sensors and so on may need replacing. Your car also has a better chance of passing when it's at its normal operating temperature - hence the occasional advice to drive around until the engine warms up and come back for a retest (with newer cars, this shouldn't be as big a player as a lot of old school mechanics believe, but it surely still has at least some effect).

Just take the test. If it fails, the test results will give a mechanic some idea of what to check and repair. I've never had a car fail. (I've known a few people that have failed, including those that bought a car and only had it tested after the buy).

Answer 3

In the emission test they check athe amount of carbon dioxide and other gases that your cars exhaust system emits when it is running,you are driving it. Unfortunately you can't check this unless it is hooked up to a emission testing machine. It does help if before you go to the emission test station that you drive your car on a open highway approx 50 miles per hour for approx 20 minuites. Was told to do this by a emission test administrator and it does work. I would also add a additive that cleans your engine as you drive-can buy at a Auto Supply store-the clerks will help you or if you have a Kroger in your area that also sells gas they now also have system where you can do a engine tuneup and add a engine cleaner -its added as you pump gas when you follow the instructions and the cost is very reasonable-below $10, for the initial tuneup then 2wks another process approx $4.+ and then whenever you pump gas $1.98 ?approx. It cleans the gung from your engine which also gives you better gas mileage for without the gunk the engine runs more efficiently. If you do not have time to do the entire procedure just go to a auto supply and ask for the best product. Be sure to also drive your car for by driving it you are releasing a lot of the excess carbons. If your car's exhaust system is not working very well and therefore you would more than likely not pass the Emission people will tell you what you should do next. GOOD LUCK!

Answer 4

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Answer 5

there are a few common things that cause a car to fail the smog check.
if it is fuel injected you are better off because it will automatically adjust for best running conditions, and it may be smoking like crazy and still pass as long as the gas cap it tight and not leaking and the ignition timing is set correctly, and the EGR is working.

if you look at the exhaust and notice it looks moist and sometimes lets out steam or water drops this is good it means its running clean.
the most important factor involved if you are trying to force a car to pass that has all the equipment installed is the ignition timing, an experienced mechanic can adjust that by ear and know when it is far enough back to make it pass. often when an old car is tuned to pass smog its drivability performance and gas millage is at its worst, so if you have someone crank the timing back to pass smog you will want them to put it back to a nice performance setting after it passes the check.

i know this from experience i drive a 1976 Datsun with over 400,000 miles on the motor, its a chore to make pass every other year, but i never have to replace a thing to make it pass, just adjust the timing and make sure the EGR is working.

one last note, the last thing you want to do before an emissions test is change the spark plugs, heres why, spark plugs burn in after awhile and thats when they work there best igniting the fuel, often new plugs will spark unevenly causing the engine to run rough and fail smog, never replace the plugs unless they really need it, and definitely not before an emissions test.

good luck
TV

Answer 6

There are many reasons why cars fail emission test. The garage that you go to can easily do something to your carburetor, like make the fuel mixture to rich or to lean. Your gas cap could be worn out and leak fumes, this would cause your car to fail. You did not list the type of car, the year it was built. Your car can also have an oxygen sensor and should be replaced if you have not ever replaced it. that just takes removing a wire and unscrew with a wrench. Make sure that your spark plugs are in good condition. Remove them recap and clean them or buy a new set of spark plugs set the gap to your cars needs. As far as the carburetor goes you need a tool called a RPM meter. Adjust the air fuel mixture screws until the meter starts to drop turn the one screw out 1/4 to 1/2 of a turn. Do the same if you have a second fuel/air adjustment. Do you have points in your distributor can be worn out if you do not have electronic ignition. Your timing on when the spark plug is suppose fire could be off a few degrees and your car will fail the test. As I said you did not give enough information about your car.

Answer 7

The hydrocarbons produced by a badly misfiring engine will fail a car quickly. No engine has perfect combustion so some hydrocarbons are normal but if the car has been stalling or having problems with RPM fluctuations on idle alot, then it may not pass. If your car doesn't have any of those problems and has been well maintained, then you shouldn't have a problem. An older car does not mean an automatic fail either.

I just took my 1992 Pontiac Bonneville in for its Delaware emissions inspection and it actually tested BETTER than most new cars. The car has about 93,000 miles and is relatively reliable. The inspector actually ran it on another machine to make sure he had the correct reading! The funny thing is it was due for a spark plug change and I had forgotten to put the fuel additive in. This is no joke, I have the test results to prove it!

Answer 8

Any number of things can cause it to fail the emissions test. Mine failed 2 years in a row - I had to get something different repaired each time before it would pass. The first time, it was a bad O2 sensor. The second time, my catalytic converter had gone out. Is your 'check engine' light on? That is a good indicator that something is amis and you will want to take it in to get it looked at. I suggest getting a tune up before taking it in for inspection - sometimes they can detect problems then. Try getting your car inspected early in the month that it is due as opposed to the end. If it fails the test, they will give you a list of reasons as to why. I think you have either 10 or 15 days after that to get the problems fixed and take it back at which point they will re-inspect it for free ( check your area for their guidelines as it may differ from ours) Good luck. I know it can be a pain and can get expensive to fix problems with the emissions system, but in the end its better than having to constantly wonder if your are get stopped and ticketed for and expired inspection sticker.

Answer 9

So far all the answers make sense. But the most important thing is to use premium gas a tank or two before the inspection. That will burn off some of the crud that will make an engine perform at less than optimum.

Change the spark plugs and the spark plug wires. That usually takes care of a few other glitches.

On the day of the test, make sure the car is thoroughly warm before you take it to the test center. That means run it like 20 miles or so on the highway.

If your gas tank lid looks like it needs to be replaced, replace it.

Make sure your tires aren't bald, and that all your lights work. (low and high beams, tail lights, back up lights, third brake light, turn signals)

The O2 sensor and the cat converter will cause the check engine light to come on, so if your light is not on, you should be fine for those.

That's about all I can think of.

Answer 10

There are many things that can cause your emissions to fail. Some of them cannot be anticipated. I own a 93 Ford Taurus and I had to replace both O2 sensors, my mass-airflow sensor, and my exhaust from the engine all the way back to the tail pipe. The catalytic converter is a huge one when it comes to emissions as I have found out first hand. My best advice is to not do anything until you have it inspected because if it passes then you need nothing. If it doesn't pass, then you spend the money to fix it. It doesn't cost anything to have it reinspected once the repairs are made. At least it doesn't in Rhode Island. I don't know about your state though.

I ONLY WISH IT WAS AS SIMPLE AS CHANGING THE OIL!!!!!!

Answer 11

They make sure your not leaking fluids, they also make sure your tires are not bald. They check your gas cap, and they have a limit on how many fumes it leaks, so if your in doubt, buy a new one. They are really cheap. They also check your exaust. They stick a tube on your tail pipe and "drive" it on these giant rollers. It will then test the exaust emitting from the tail pipe. If there is too much toxins, then they will fail you. Generally though, they will tell you why it failed if it does. They also check to see if your catalytic converter is present and working properly. One more thing, if your car has passed within the last two years, then you might not have to even get it e-checked at all. Also, I would find out from the previous owner if it did or didn't because if you car fails, they will make you pay a fee if it has failed too many times before. Even if YOU just bought it. You may have bought someone else's problem. Typically, if it didn't fail last time and it DID fail this time, you shouldn't have to pay for it. You typically pay if it fails more than 3 times, or if the car PASSES e-check. I would call your local e-check station for the details about payment and how many times it can fail. Good luck!