Catalytic Converters Chapter 28
Cerium is an element in the catalytic converter that stores oxygen. Using an exhaust gas analyzer, at idle what should a good O2 reading be and what should the CO reading be?
0
List seven conditions when the catalytic converter is ready for testing.
1. Closed loop status achieved 2. IAT > 32°F 3. ECT sensor > 165°F 4. MAF sensor input between 15 and 22 g/sec 5. Engine load < 65% and steady 6. RPM <4000 RPM 7. All of above condition consistent for 4 mins
List three main causes of converter damage.
1. Contamination 2. Excessive temperature 3. Improper air-fuel mixture
What are the four good gasses that comes out of the catalytic converter?
1. H2O 2. Nitrogen 3. Oxygen 4. Carbon dioxide
What are the three bad gasses that go into the catalytic converter?
1. HC 2. NOx 3. CO
What three things that can cause a catalytic converter to fail?
1. Ignition problems 2. Fuel problems 3. Mechanical problems
If the catalytic converter is working properly, what would the temperature increase form the inlet to the outlet?
10% or more
What should be the engine vacuum be at idle?
17-21 in.Hg
How long should you wait to fully warm the CAT?
2 minutes
There are approximate ______ openings per square inch and wall thickness of ______".
400 0.006"
The light off temperature of the catalytic converter is ______ and allows it to work at ______ efficiency.
500°F and allows it to work at 50%
How long should you keep it at 2500 RPM?
60 seconds
How long is the catalytic converter warranty?
80,000 miles or 8 years
The CAT will reach between ______ and ______ when it is at maximum efficiency.
900°F and 1,600°F
What is the back pressure specifications at idle?
< 1.5 PSI
What is the back pressure specifications at 2500 RPM?
< 2.5 PSI
What is the purpose of the catalytic converter?
After treatment device to reduce exhaust emissions on the output side of the engine
What is Cerium?
An element that can store oxygen
______ are applied on the ______ of the washcoat.
Catalytic material Top
What material and shape is the catalytic converter made of?
Ceramic honeycomb shape
What does the chemical reaction do, and what is produced?
Changes harmful emissions to non harmful exhaust emissions
If the O2 levels are higher than specifications using an exhaust gas analyzer, at idle what should be done next?
Check CO level
What is a catalyst?
Chemical to start a chemical reaction
What can be done to further test the catalytic converter to see if it can convert to HC into harmless gasses?
Create ignition misfire and check temperature change
What can damage the ceramic substrate?
Expose to shock or severe jolts
When the 3-way catalytic converter is operating properly, the post converter HO2s is ______.
Far less active
Why are there two different types of catalyst materials in the catalytic converter?
First section is for NOx and back section is for HC and CO
What two gases in the catalytic converter are further oxidized to produce carbon dioxide and water?
HC and CO
Using an exhaust gas analyzer during a snap throttle, what should a good O2 reading be? And what does this indicate if it is above this?
Less than 1.2% Converter not working
What is a LOC and why is it used?
Light off converter
The CO molecule enters a ______, which has been created in the porous ______. Then the CO molecule enters a ______. CO molecule is ______ onto a ______ side. The CO molecule is converter to a ______.
Micropore Washcoat Smaller Micropore Asborbed Catalyst CO2 molecule
What is a poisoned CAT?
Micropores is all plugged
What should the vacuum reading be at 2500 RPM if the exhaust is restricted?
Much lower than at idle
Where is the best place for the location of the catalytic converter and why?
Near to engine to use heat from engine for effective cat operation
What two harmless gasses does oxides of nitrogen convert to?
Nitrogen and oxygen
Can these three elements wear off or run out?
No
Do catalytic converters wear out?
No
If the catalytic converter temperature difference is not within specification is the CAT defective?
No because very clean running engine will not have that much temperature change
What can cause the catalytic converter to not function properly?
Not having proper air fuel-mixture and ignition system defects
Where is the catalyst located?
On the surface material in the catalytic converter
On older vehicles, what part of the catalytic converter reduces NOx?
Oxidation beads
What are two fault codes related to a failed catalytic converter?
P0420 and P0422
The substrate or ceramic material is coated with a ______ called the ______.
Porous aluminum Washcoat
Why is it called a three way catalytic converter?
Reduces NOx, HC, and CO
If the O2 levels are higher than specifications using an exhaust gas analyzer, at idle what should be done next?
Replace CAT
What should be done if the ceramic substrate is damaged?
Replace unit
The catalytic converter substrate contains small amounts of ______, ______, and ______.
Rhodium, palladium, and platinum
Where is the O2 sensors located to test the catalytic converter?
Right before and right after catalytic converter
What should the vacuum reading be at 2500 RPM if the exhaust is not restricted?
Slightly less than idle
Explain the CAT tap test.
Tapping CAT with rubber mallet to listen for rattle. Rattle means replace
