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Altering all O2 sensors
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HALS-GUNSMITHING Offline
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Post: #1
Altering all O2 sensors
If the post cat sensor is suppose to messure the difference from before to after the cat I would think that you would have to make the same modifications to the post cat sensor or the difference between the 2 will vary. Does this make sence to anyone?
11-06-2008 09:57 PM
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JonnyBravo Offline
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RE: Altering all O2 sensors
I believe the ECU doesn't really care about what exact voltage the second (post) O2 sensor is, but just that it doesn't fluctuate as much as the pre-cat sensor. If the cat is working good, then the post sensor should be much more flat-lined than the pre-cat sensor, due to the modified exhaust gasses done by the cat. This is how it can tell if the cat is still good or not.

'94 Ford Explorer 4.0L - Fargo, ND
(This post was last modified: 11-07-2008 11:10 AM by JonnyBravo.)
11-07-2008 11:09 AM
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colchiro Offline
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Post: #3
RE: Altering all O2 sensors
I'm convinced the post cat o2's aren't too fussy. The only people I know of who have trouble with the post cat o2's are high perf types with headers and low restriction intakes.

It's rare to need to do anything with the post-cat sensors.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
11-07-2008 03:32 PM
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thomasbala Offline
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RE: Altering all O2 sensors
JonnyBravo Wrote:I believe the ECU doesn't really care about what exact voltage the second (post) O2 sensor is, but just that it doesn't fluctuate as much as the pre-cat sensor. If the cat is working good, then the post sensor should be much more flat-lined than the pre-cat sensor, due to the modified exhaust gasses done by the cat. This is how it can tell if the cat is still good or not.
Best explanation of post O2 sensors I've seen yet. If you look hard enough on the net you can find post O2 simulators. Why would anyone need a post O2 simulator? Had me stumped for [I won't tell you how long] until I figured out it's used for polluters running w/o cats and don't like to see the CEL reminding them of their defiling mother earth. The low gas prices won't last; spread the HHO word; get prepared for the next onslaught of big oil and fuel price increases.
11-07-2008 07:59 PM
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colchiro Offline
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Post: #5
RE: Altering all O2 sensors
thomasbala Wrote:The low gas prices won't last; spread the HHO word; get prepared for the next onslaught of big oil and fuel price increases.

I agree with you on that one.Hmm

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
11-07-2008 08:35 PM
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Gary Offline
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Post: #6
RE: Altering all O2 sensors
They make post-cat o2 simulators for guys who remove the cat for off-roading. About $100. - all it does is put out a .47 volt or something like that signal. I read that it won't work for the pre-cat sensors.
11-08-2008 06:27 AM
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