Car Automotive

Posts Tagged ‘emissions’

From time to time, reports circulate about vehicles that have failed an exhaust emissions test. Often, it seems that an assumption has been made that the exhaust catalyst is defective, a new catalyst has been fitted and when retested the vehicle still fails the exhaust emissions test. From this point things can often get worse. It is, therefore, useful to make an examination of the techniques that should prevent such misdiagnosis from happening.

The pre-catalyst oxygen sensor is an important element in the control system that regulates the mixture strength (air–fuel ratio) in spark ignition engines. the oxygen sensor samples the exhaust gas before it enters the catalytic converter and produces a signal that tells the ECM the air–fuel ratio of the mixture that is entering the combustion chambers. It is a feedback system.

The oxygen sensor signal is used by the ECM to change the amount of fuel injected so that lambda is kept in the range of approximately should remind you of the principle.Should the oxygen sensor be disconnected, there will be no feedback to the ECM, which will probably have been programmed to use a substitute value to cause the ‘limp home’ mode to operate and to minimize the possibility of damage to the catalyst. Add to this the fact that, like the catalyst, the oxygen sensor needs to be at an operating temperature of over 300?C for it to operate efficiently, and it becomes evident that electrical testing of the oxygen sensor is work that requires care and attention to detail.

The European Union wants to establish a position as a forerunner of climate protection and to reduce total CO2 output by 30 percent on 1990 values by 2020. The officials in Brussels have even set their sights on a 60 to 80 percent reduction in carbon dioxide emissions by the middle of the century.

This is a highly ambitious target that could only be achieved through a massive collective effort on the part of all CO2 emitters – households, industry and transport.The public debate, however, often gives the impression that the automobile is primarily responsible for potential climate change. Despite the fact that passenger cars only account for twelve percent of total CO2 emissions in Germany, many environmental activists in particular consider personal transport to be the root of all evil, reason enough for politicians to pay particular attention to reducing passenger car emissions.

In December 2007, the European Commission published a proposal to limit
the CO2 emissions of all passenger cars registered from 2012 onwards.