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        General >> Give/Need advice to/from others >> Removed catalytic converter, o2 sensors
        
(Message started by: Martinss on Oct 5^th, 2012, 4:14pm)

Title: Removed catalytic converter, o2 sensors
Post by Martinss on Oct 5^th, 2012, 4:14pm

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?

Title: Re: Removed catalytic converter, o2 sensors
Post by Mike H on Oct 5^th, 2012, 4:51pm

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. (?)

Title: Re: Removed catalytic converter, o2 sensors
Post by Matt on Oct 5^th, 2012, 6:00pm

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.

Title: Re: Removed catalytic converter, o2 sensors
Post by Tenfut on Oct 5^th, 2012, 7:19pm

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

Title: Re: Removed catalytic converter, o2 sensors
Post by amigafan2003 on Oct 8^th, 2012, 7:25pm

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.

Title: Re: Removed catalytic converter, o2 sensors
Post by Martinss on Oct 8^th, 2012, 7:54pm

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?

Title: Re: Removed catalytic converter, o2 sensors
Post by amigafan2003 on Oct 13^th, 2012, 10:58pm

on 10/08/12 at 19:54:39, 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?

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?

Yes, all the same but the fronts have longer wiring - if in doubt order a front one and you can loop the wiring up.

Title: Re: Removed catalytic converter, o2 sensors
Post by Martinss on Oct 14^th, 2012, 9:31pm

Ok, thanks for the info. :)