Catalyst low efficiency Cel, how is it fixed??

redwing24

My other ride is a Ruckus
my 99 had a gutted out cat when I bought it, and replaced it with a hi flow cat and still get it. Will a magnaflow cat fix this or can you tell me how it can be fixed???
 

red98teg

Keep on Truckin
could be other things further up the line, that are causing your cat to crap out...ever any other cels?
 

redwing24

My other ride is a Ruckus
It has an aftermarket header on it, not sure what brand or anything. could be a racing header, I don't know. How do you tell what kind it is??
 

DA_Integra

Not White, Pearl White
Check the O2 sensor in the header that usually sets the cel off.
 


redwing24

My other ride is a Ruckus
so looking at the diagrams, is there suppost to be 3 or 2 sensors?
 
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LSvtecboi

New Member
in most cases if it says low cat.. it is the second o2 sensor (after the cat) that has gone bad
 


redwing24

My other ride is a Ruckus
wont a test pipe set it off too, just like my hi flow cat. so will a hi flow cat set it off??? or was is my o2 sensor shit then. because my cel was on with my old gutted out cat, so I bought a Hi flow cat instead and it still is on. Is it the cats fault or the o2 sensors fault?
 

redwing24

My other ride is a Ruckus
where is the best place to buy them?? I see them on ebay pretty cheap but how do you know which O2sensor is it???
 

Spody02

Name: Cody
what code are you exactly getting?
do you have obd2 port reader thingy
if not
go get one and tell us what the code is
cause there is like 3 different ones with the exhaust and 02 senors
and if you can tell us the code your getting then we can tell you what you need to fix
 

silver_dc435

Chris
if the code is P0420 (the actual OBD 2 code), that indicates that the converter is below efficiency threshold. what it means is that the front and back O2 sensors are basically reporting the same information, thus inferring that the converter is not converting anything.

the front O2 sensor is constantly changing as it's the engine's only indication of lambda in the exhaust, so the computer constantly changes injector pulse width to keep an 'average' stoichiometric mixture. it cycles between rich (great for lowering NOx) and lean (great for not burning up the catalytic converter).

the back O2 sensor should modulate between a very small band, not near the frequency nor amplitude of the front. if this back sensor starts to act like the front sensor, the converter is not working. you can try a new sensor (i did, but it did not fix it), but the sensors generally have their own CEL codes. the only true test is a smog test to find out if the converter is working (with some sort of machinery to quantify the constituents of the exhaust).

generally, putting a high flow (or 'test pipe') doesn't work as well as the OBD 2 converters, thus the converter is below threshold. it poses no risk to the actual operation of the vehicle, but if there are smog inspections in your area then that's a problem. well, if they actually do more than just plug a computer into it. if that's the case, it's easy to purchase ready-built 'O2 sensor modulators' or 'emulators' that will modify the output of the O2 sensor and send a voltage to the ECM that fools it into thinking everything works. that's what i did. i passed the OBD 2 smog test. with a bad converter.

the only true fix is to by a converter that is certified smog legal for OBD 2 (test pipes or high flows are generally not, or are 'not for use in california' or 'not for highway use').
 
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