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Topic: Removed catalytic converter, o2 sensors (Read 1281 times) |
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Martinss
Newbie
Ford Sierra 2.9i BOB
Posts: 27
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Removed catalytic converter, o2 sensors
« on: Oct 5th, 2012, 4:14pm » |
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Hello!
Have somebody removed catalytic converters from their 24v BOB? Mine were already gone, so I wonder, what does ECU thinks about this, as first lambda sensors and second lambda sensors read the same data, does ECU go in emergency mode, does it give check engine light? And if so, what is solution to give different data to second sensors? Or I can easily remove them?
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Mike H
Senior Member
Renault Clio
 
Posts: 2594
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Re: Removed catalytic converter, o2 sensors
« Reply #1 on: Oct 5th, 2012, 4:51pm » |
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When my lambdas went down it wouldn't pass MOT on emissions, cat most likely shot as well (read as, non-op)
Excellent page here all about lambdas,
http://www.picoauto.com/applications/lambda-sensor.html
Note in first graph the sensor presents a Voltage signal of around slightly under half a Volt. (Averaged)
Lower Voltage makes it richer, higher Voltage makes it leaner.
I would imagine post cat sensors would read leaner as cat is supposed to take out any remaining hydrocarbons. (?)
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Mike H
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Matt
Senior Member
Manual'd and a 4.0 in the making
Posts: 2816
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Re: Removed catalytic converter, o2 sensors
« Reply #2 on: Oct 5th, 2012, 6:00pm » |
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my first cossie had the cats removed (can as there but internals knockef out)o
passed mot like it and had no lights on dash, the ecu only really uses the first pre cat o2 sensors for fuel trimming etc. you can unplug the second set and after 10mins or so the ecu will omit them, may run a bit rough at first.
if you look at the v6 mondeos they only have pre cat o2. ive had my manual'd cossie running on mondeo st ecu as its better then fooling tge car to think its in neutral.
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FDS2000 Scans - Birmingham
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Tenfut
Full Member
White Cosworth Saloon
Posts: 621
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Re: Removed catalytic converter, o2 sensors
« Reply #3 on: Oct 5th, 2012, 7:19pm » |
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Whats the best route to take to swap the pre-cat sensors, from underneath or top? Also what is the spanner size, is it 22m?
TIA
Tony
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amigafan2003
Full Member
I'm a YaBB newbie!
Posts: 972
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Re: Removed catalytic converter, o2 sensors
« Reply #4 on: Oct 8th, 2012, 7:25pm » |
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they don't measure the same thing technically.
The pre cat sensors are used by the ecu to trim the fuel when in closed loop mode. If these sensors go you get a rough running engine at cruising speed (engine ignores lambda feedback at wot - i.e. it goes open loop).
Post cat sensors do not affect fuel trims at all - they are simply there to monitor the state of the catalytic converters - i.e. ensure they are doing their job properly.
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Martinss
Newbie
Ford Sierra 2.9i BOB
Posts: 27
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Re: Removed catalytic converter, o2 sensors
« Reply #5 on: Oct 8th, 2012, 7:54pm » |
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So if post cat sensors sees that cat isn't working, it just gives check engine and thats all, no effects on performance/mpg?
edit: Also, are all 4 o2 sensors on 24v the same? Or they are different? And does all 4 sensors have 4 wires?
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amigafan2003
Full Member
I'm a YaBB newbie!
Posts: 972
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Re: Removed catalytic converter, o2 sensors
« Reply #6 on: Oct 13th, 2012, 10:58pm » |
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on Oct 8th, 2012, 7:54pm, Martinss wrote:| So if post cat sensors sees that cat isn't working, it just gives check engine and thats all, no effects on performance/mpg? |
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No check engine lights as Scorps don't have them  It will just store an engine code. But no, shouldn't affect the running at all.
Quote:| edit: Also, are all 4 o2 sensors on 24v the same? Or they are different? And does all 4 sensors have 4 wires? |
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Yes, all the same but the fronts have longer wiring - if in doubt order a front one and you can loop the wiring up.
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Martinss
Newbie
Ford Sierra 2.9i BOB
Posts: 27
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Re: Removed catalytic converter, o2 sensors
« Reply #7 on: Oct 14th, 2012, 9:31pm » |
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Ok, thanks for the info. 
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