remove CAT n airfuel readin bcum weird?

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3,000 RPM
Senior Member
Feb 14, 2004
ok here i go.. as u guys noe dat the CAt is located at the extractor in de after i removed the CAT.. my airfuel reading bcum crazy... so wut is in my mind is.. whether de air flows freely now den last time being block by dat CAT n de O2 sensor get to read those block air n now de air flows freely n de O2 sensor is not dat sensetive.. slow respond..?
by right the o2 sensor should be placed before the cat, or else it might get erroneous readings
yeah.. de loc of de sensor is still at the same place.. just dat i've poke our those CAT internals.. n kelisa extractor is together wif de CAT.. i just poke n clear our all those stuffs..
maybe some of that stuff you failed to clean properly, so it lodged itself onto the o2 sensor?

bevery careful with the o2 sensor, very fragile
when im driving .. de airfuel reading is ok.. means when im accelerating.. but when i slowdown.. wana make turning.. it suddenly go to very rich.....
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did u put anything to replace your CAT? and by the way, restrictions and non restrictions can even affect ur o2 sensor and ur air fuel, due to the rate of air flow...

hope i'm right

this is how de stock extractor look like... de 3 arrows is de lubang la.. n dat is my CAT n o2... n i didnt replace anything after i tookout de CAT..

thteh.. yeah.. i tot of dat also.. but duno whether correct anot la..
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how lean are you talking about?

seriously, the narrowband o2 are only good to display 14.7, richer or leaner than that its pretty inaccurate. if your car's fuel consumption didn't go up, idles properly, no knocking noises, then its okay. But if you are really paranoid, go hook up a wideband o2.

Sorry for the late reply.

It's due to a different flow pattern and rate that has affected the reading. I think resetting the ECu and let it adapt to the new flow rate will solve the problem. Resetting? You know how lar.. haha!!
thanks man.. yeah did resetting ...but still same la.. will giv it a few days more...if still de same.. nuthin i can do kekee..
your exhaust has better flow now. So you are leaning out, you can bring it back to normal by adding more fuel with piggyback modules, then you will get slight increase in hp. Turst me, that is what we called, less-backpressure, a step to increasing horsepower of your engine
sorry guys.. i got miss concept bout airfuel.. damn.. all along i was reading it wrongly hehe.. now my airfuel is not lean.. its rich.. suddenly running rich.. yeah.. im retuning it..

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