Maryland Cherokee Club
07-21-2012, 12:20 PM
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This made me laugh! Good for him! ... A Marine was deployed to Afghanistan. While he was there he received a letter from his girlfriend. In the letter she explained that she had slept with two guys while he had been gone and she wanted to break up with him. AND, she wanted pictures of herself back. So the Marine did what any squared-away Marine would do. He went around to his buddies and collected all the unwanted photos of women he could find. He then mailed about 25 pictures of women (with clothes and without) to his girlfriend with the following note: "I don't remember which one you are. Please remove your picture and send the rest back."
I like that story. Has come up in just about every war. At least since the Korean war anyway.
07-21-2012, 12:23 PM
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Year: 1999
Model: Cherokee
Engine: 4.0
Check engine light went on the other day so I went and got the code read. P0420. I did some reading and also talked to Justin (Dukie) and it looks like it's either going to be the catalytic converter or the downstream O2 sensor. How do I figure out which one it is?
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
07-21-2012, 12:25 PM
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Year: 1998
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Check engine light went on the other day so I went and got the code read. P0420. I did some reading and also talked to Justin (Dukie) and it looks like it's either going to be the catalytic converter or the downstream O2 sensor. How do I figure out which one it is?
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
The PCM compares switch rates between the front O2 sensors and the downstream catalyst monitors. The catalyst monitors are often mistaken as O2 sensors, and they are, but that is not their job, or what they are called. By comparing the switch rates between the front (before cat) and rear (downstream of cat) the PCM knows if the cat is affecting the exhaust, and how much it is affecting the exhaust. If it sees little or no effect on the exhaust gases that have passed through the cat, then it decides that the cat is not working anymore, and sets a P0420, or a P0430, depending on which bank it is. To check this yourself, you will need to bring up data stream on your scanner, watch the upstream and downstream O2 parameters and see if they are following each other closely. If the cat is working right, you should see a fairly rapid switch rate, probably 5 or 6 times a minute on the front O2, but almost a flat line just above .5 volts on the rear. If the rear is switching often you probably need a catalytic converter.
Last edited by jimmy21669; 07-21-2012 at 12:31 PM.
07-21-2012, 12:25 PM
CF Veteran
Check engine light went on the other day so I went and got the code read. P0420. I did some reading and also talked to Justin (Dukie) and it looks like it's either going to be the catalytic converter or the downstream O2 sensor. How do I figure out which one it is?
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
Jeep just turned 101,000 miles. Original exhaust and O2 sensors.
Upgrade exhaust, and change O2 sensors and be done.
07-21-2012, 12:28 PM
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07-21-2012, 12:43 PM
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07-21-2012, 12:50 PM
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07-21-2012, 12:56 PM
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Year: 2000
Model: Cherokee
Brian, lemme know if its the cats (its one piece) i gots a hook-up--
opps, mebbe its not,mine was though, regardless, i gots a hook-up
opps, mebbe its not,mine was though, regardless, i gots a hook-up
07-21-2012, 01:12 PM
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07-21-2012, 01:18 PM
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07-21-2012, 01:18 PM
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You could....you would see the front switching....the the rear staying mostly at -.05v. If you get nothing out of the rear, it is bad...if you get it switching, cat is bad....
Can you go to Advance and borrow one?
07-21-2012, 01:23 PM
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