all the threads i read on the subject (straightpipes, to be exact) discussed performance value, sound issues, etc........... the question i have is: what effect does unplugging the o2 sensor (the one in the cat) have on the car and motor? i've seen that the ecu will toss a code, but is the a/f ratio affected in any way? will removing that o2 sensor cause any problems with overall performance? thanks in advance.

 

The ECU has no idea if the car is running rich or lean and will go into limp mode.

 

really? so what's with people running straightpipes on their factory ecu's?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Team 4R &raquo;</TD></TR><TR><TD CLASS="quote">really? so what's with people running straightpipes on their factory ecu's?</TD></TR></TABLE>

weld a bung on the strait pipe so you can run your o2 sensor.
I know when my o2 went bad, my car would run like crap, and had no power.....once i replaced it, i was back in business.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Team 4R &raquo;</TD></TR><TR><TD CLASS="quote">really? so what's with people running straightpipes on their factory ecu's?</TD></TR></TABLE>

depends on OBD 1 or OBD 2, OBD 1 deosn't looking for the second O2 sensor, and people have test pipe on OBD 1 motor is fine, since there is one O2 sensor on header
OBD 2 have no second O2 sensor on the cat is OKAY too, but it will have CEL

but if there is no O2 sensor, then it is no good at all

 

im only running one o2 sensor on my 99 ek , as long as you run the primary o2 youll be ok , youll just throw a cel. the secondary o2 doesnt make a/f changes

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Spade &raquo;</TD></TR><TR><TD CLASS="quote">The ECU has no idea if the car is running rich or lean and will go into limp mode.</TD></TR></TABLE>Not quite. The primary O2 sensor (on the header) reads the lean/rich mixture. The secondary O2 (on the cat) determines if the cat is working or not. It should be reading a fairly steady misture, otherwise it'll trigger the CEL teling the ECU that the cat is not working properly/clogged, etc.

OBD1 ECUs don't have a scondary and can run wihout a cat with no performance problems. Also with OBD2, but the CEL will be on unless you convert to OBD1 or get an O2 simulator.

 

ah, dammit....... conflicting thoughts. i guess i'll just have to unplug it and see what happens...............

 

Since you are in Cali, you will not pass emissions because of the thrown code.

 

i've ran my car with the secondary o2 sensor disconnected for quite a while, runs exactly the same expect i get a red light indictaing its not plugged in, car is jdm vti