What Happens Actually in an OBDII Release Test

I've seen many people talk about OBD-II emission tests in various Internet forums. Often one is confused: "We did not succeed!" or "Do I have my OBD II test on my 1994 vehicle?" As OBD-II has triggered or exchanged 96 or more vehicles in most countries or will replace or replace synchronous tests, I thought I would give some introductory information on OBD-II emission tests for people. I'm not talking about OBD-II details, different protocols, or about how to set up an OBD II vehicle. Only expectations in the emission process.

First of all, it's a very quick background: in California, the 1966 model year, California exhaust gas control systems (catalytic converters) are required. This was adopted in the United States in 1968 and finally became the 1970 Clean Air Act, which required difficult emission standards for manufacturers. Finally, automakers have found that switching to electronic control of engine control has allowed them to meet these needs. Electronics have become more and more sophisticated and standardized over time, and now we have a standard protocol (OBD-II) that these computers are connecting to.

Today: Many states, California, Massachusetts, New York, Illinois, Washington, New Hampshire and also some or all counties require mandatory emissions monitoring. Typically, this is part of the vehicle registration and renewal process. Until 2000, this meant that the car was hanging on a dynamo, sniffing in the exhaust pipe, and measuring how many percent of the air leaving the vehicle would be clean. However, in 2000, the EPA started implementing an "OBD II emission test" and many states have accepted or are being adopted.

The OBD-II test is the OBD port in the car (usually under the dash or behind the cigarette lighter) and asks the car's computer whether the emission devices in the vehicle operate within the required efficiency limits. This is advantageous over the sniffer because it is much quicker, more consistent (theoretically) and even harder for those than fast cars than the jury to have a large catalytic converter in the morning before the test to spy on the vicious mobiles

OBD-II tests are very easy to operate. The car ECU expects conditions that represent normal driving and then check the values ​​of some sensors to make sure the equipment is working properly. It typically examines systems such as catalyst, exhaust gas recirculation (EGR) and evaporative emissions. These results are stored internally and the computer only queries these results during the audit time. The control machine also checks the computer to determine if there is an error code and if the control engine light (also known as MIL) is also set. If the tester establishes that the emission equipment is OK, there are no internal defects that the car was unable to tell you and the control engine light does not illuminate, the car is discharged without further emissions being required

In order for the wagon permanently to say that the vehicle is operational, it must examine its systems for a specified number of "driving cycles". Driving cycles are defined differently by different car companies. Some driving cycles are the time that the key is first turned on until it is switched off. For others this is any 10-minute period for non-driving driving, etc. This is where the concept of standby is introduced. If the vehicle ECU returns for any reason (replacement, weak battery, defective sensor, etc.), it will reset the "standby monitors" inside the ECU. These are a number of flags that determine whether the car is ready to enforce the status of emission systems. The vehicle must therefore be driven to a predetermined number of drive cycles so that the ECU receives all the necessary information from the state not yet known and actually tests the emission systems.

If a car is examined while it is not ready, the car will remain "on standby" on the control computer. For cars sold between 1996 and 2000, the emission test is considered to be a mistake if two of the emission systems are not ready. In the later vehicles only one is not ready. Improving the inadequate readiness is to drive the car up to 500 miles and try again. After that, if you still fail, a trader or someone with a factory diagnostic equipment will have to force the vehicle to be ready for the emission measurement.

Modified Cars: OBD-II is a problem with modified emission systems. In the past, you could just keep the factory exhaust in a corner of your garage and see it, but now the electric tattle tail will still catch you. You can use a data recorder such as your autodealer: http://www.obd-2.com/ to check if your car is ready and you think the release is in a happy state. This, of course, can only be used for off-road vehicles.

The common problem of modified cars is secondary o2 sensors. Part of the OBD-II tests involves determining the efficiency of catalyst (or catalyst pre-catalysts) by checking the value of oxygen sensors after the cat. If your off-road vehicle does not have this equipment, the vehicle will probably be unsuccessful. A common solution to this problem is installing an oxygen sensor simulator that gives a false signal to the ECU of the car, which mimics what you expect and feels that everything is fine. Finding "o2 simulator" fast internet searches for more information on this topic. Finally, do not forget that you have to drive many miles to get ready for transmission. In some extreme cases, more than 1,000 miles are required. So, if you plan a car for a few months to run a long project and have a check time, it will be better to examine the vehicle before taking it off the road and restoring the ECU.

Source by Henry Cipolla

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