Emissions Testing tips

[n2o4ever]

What tips do you guys have in passing emissions testing, people have told me to run the car on the highway and get it nice and hot then take it to get it tested right away.

[UncleBob]

depends on what type of test it is.

As a general rule, yes, get it on the highway, get everything good and hot. Wait for a day that there's little traffic at the testing station, so you don't spend much time idling, waiting for the test. And definitely never shut off the car while waiting

[maxwedge]

Not too critical on OBD11 cars with preheated o2 sensors although can't hurt. Of course as mentioned cats can't be cold.

[INF3RN0666]

To my knowledge, the test requires that the testing facility warms up your car to the appropriate state guidelines before beginning to take readings. So you should drive on the highway, but having your car HOT when you get there just avoids having the tester from idling your car before the test. So if the place is busy, then you just wasted gas getting the car "hot". They will do an idling test, and a 2000 RPM test. From my experience, if you get an early morning reading, the values seem to come out lower. I know it sounds stupid, but the machines are not as accurate as people think they are. My car has excessive bore clearance and you can tell that it has minor ignition problems. Yet, it registered 0's for almost everything when I took it in at 8:30AM.

My recommendation, not sure if all the hype is true, is to run at least a half tank of ethanol-10 mix in your car a week before the test. It helps to clean carbon deposits. And yes, highway driving does help because it's constant exhaust flow at a good RPM range. Other than that, make sure your plugs and wires are good, EGR is running, and catalyst doesn't have more than 300000 KM on it. If you have some ignition problems with your car, then running 89 octane fuel might help just enough to pass the test. The test is a pass or fail, no grey areas (more than XXX Carbon Monoxide reading = fail, etc).