The perfect internal combustion engine would put the exact amount of fuel and air into the combustion chamber.
The catalyst efficiency monitor verifies that the catalytic converter is operating at a high enough efficiency rating to keep exhaust emissions within predetermined values. The PCM compares the signals from the upstream and downstream oxygen sensors to determine the state of the converter. These “tests” are called the readiness monitors.
If you are replacing a catalytic converter for a customer, it is not the same as replacing a muffler or pipe. Since the catalytic converter is an emissions device that is federally and locally mandated, documentation is just as key as proper installation.
Nothing is worse that an EVAP code after a fuel pump has been replaced. Discovering that the tank needs to be dropped again to address a problem can kill shop productivity and profitability. Keep reading for tips that can help you avoid comebacks and dropping the tank for a second time.
As part of OBDII, Mode$02 for the logging or freeze frame data was created. This diagnostic protocol saves data PIDs and information when a code is set. In 1995, freeze frame gave technicians a powerful diagnostic tool that was previously only available on expensive factory tools.
On some Mazda vehicles, a sulfur smell or rotten egg odor may be noticed coming from the exhaust system. The odor is usually noticed after a cold start, fast idle, extended periods of idling and full-throttle acceleration. The sulfur smell is not an indication of an engine concern and will not cause reduced driveability or durability of the engine or any of its emission components.
The perfect internal combustion vehicle would be able to put the exact amount of fuel and air into the combustion chamber. If the perfect combustion event were to occur, you would get nothing more than water and carbon dioxide as byproduct. There would not be any unburned fuel or oxygen. Combustion would occur at the right temperature so oxides would not combine with nitrogen and carbon to form nitric oxides (NOx) and carbon monoxide (CO). This perfect car would not need a catalytic converter or any other emission-control device.
The Diesel Particulate Filter (DPF) is a ceramic filter that has thousands of tiny channels or honeycomb-shaped openings that trap the soot onto the channel walls and prevent the particulate matter (down to 1 micron) from exiting out the tailpipe. The honeycombed inner structure is covered with a layer of a chemical catalyst that contains small amounts of precious metals, usually platinum or palladium.
The catalyst efficiency monitor verifies the catalytic converter is operating at a high enough efficiency rating to keep exhaust emissions within the predetermined values. The PCM compares the signals from the upstream and downstream oxygen sensors to determine the state of the converter. These “tests” are called the readiness monitors.
Crankcase vapors are routed through the positive crankcase valve (PCV). The PCV valve is a simple spring-loaded valve with a sliding pintle inside. The system allows the vapors to be siphoned into the engine using engine vacuum.
Andrew Markel discusses the development of the EVAP system as emissions standards changed over time. Sponsored by Standard.
For over 30 years, vehicles have used at least one oxygen sensor for fuel control, but modern emissions sensors are quite different. The traditional switching oxygen sensor is still common; yet most late-model vehicles are moving toward wide range, air/fuel sensors for primary fuel control.