By Erik Hensley
Hensley's Auto does exhaust repair in Santa Rosa. The exhaust system consists of everything from the exhaust manifold to the muffler.
Exhaust leaks result in exhaust fumes entering the vehicle so it's important to fix them. Over time your exhaust pipes, muffler ,exhaust manifold, and catalytic converter can develop leaks and cracks that need to be repaired.
How different exhaust components work
Catalytic converter - The catalytic converter is a big part of the emission control system on your vehicle.
Converters started being used on vehicles in 1975 in order to reduce exhaust emissions. A common nickname for the catalytic converter is a CAT.
The catalytic converter increases the surface area that the exhaust emissions pass over in order to continue the burning process. Through a chemical reaction with precious metals the emissions that were once harmful are converted to less harmful CO2, which is a byproduct of complete combustion.
Vehicle emissions are reduced by 50% to 70% by the catalytic converter. A defective converter is a very common smog failure. There a a few ways that a catalytic converter can be test.
Heat - When a catalytic converter is working it will be hotter in the back because the burning process is continuing. The temperature measured with an inferred heat gun should be 50 degrees hotter.
Cranking CO2 -
Step 1: Warm up the converter by holding the vehicle at 2500rpm for three minutes.
Step 2: Disable the ignition system on the vehicle. - make sure the fuel system is not disabled.
Step 3: Crank the engine and see if the CO2 is above 7.5%. Since the converter continues the burning process when it is working you will see a rise in CO2 when the converter is working.
Intrusive Test - This test is the industry standard. You measure the emission before and after the CAT. You should so a reduction in the emission after the converter of at least 50%.
Vehicle model year 1996 and up computer systems will check the catalytic converter and set the check engine light if the converter is bad. Since a Catalytic converter uses oxygen when it is working the computer will monitor the front O2 (before cat) sensor and compare it to the rear(after cat). If the converter is working there will be a decrease in oxygen sensor activity on the rear sensor.
If your looking at an emissions report there will usually be about a 13% CO2 reading and an oxygen reading above 2%. If you have high emissions and no oxygen left over the converter may be good. Since the converter needs oxygen to work replacing the cat probably wont help.
Before change a converter make sure the vehicle is in fuel control and the vehicle is running on all cylinders.
Catalytic converters can plug up resulting in loss of power. If your vehicle is low on power a simple back pressure test of the exhaust system will help verify if your problem is related to a restricted exhaust system or not.
When replace a catalytic converter in California there needs to be an executive order stamped on the converter, This number is cross referenced by the smog technician to make sure the correct converter is installed.
Exhaust Muffler - The muffler consists of sound cancelling baffles.
Exhaust Manifold - The exhaust manifold attaches to the cylinder head of the vehicle. Exhaust manifolds are prone to cracking. Also some exhaust manifolds have catalytic converts built into them.