dudeomega2000

I recently took the cat out in my civic and there are times where the exhaust will backfire. Is this normal???? How can i fix this?

Syndacate

Is the car a '92-'95 or a '96-'00?

dudeomega2000

96

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dudeomega2000 &raquo;</TD></TR><TR><TD CLASS="quote">96</TD></TR></TABLE>

Then the ECU will look for a secondary O2 sensor in the catalytic converter. If you removed the catalytic converter, what did you do with the secondary O2 sensor?

slowcivic2k

Removing the cat will cause the pulses to "pop" out the exhaust, but on complete decel, it should be quiet, if it pops, your throttle plate may be hanging open a bit. The ECU will cut all fuel to the injectors on decel, if it senses an open throttle, it will continue to feed fuel.

If it has a faint pop at idle you may want to check your timing.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">Removing the cat will cause the pulses to "pop" out the exhaust, but on complete decel, it should be quiet, if it pops, your throttle plate may be hanging open a bit. The ECU will cut all fuel to the injectors on decel, if it senses an open throttle, it will continue to feed fuel.

If it has a faint pop at idle you may want to check your timing.</TD></TR></TABLE>

True, but without the secondary O2 sensor, won't his fuel trim be off, as well?

In the name of safety wouldn't the ECU richen it up a bit causing more pulsing than normal?

97Ej6mike

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">

True, but without the secondary O2 sensor, won't his fuel trim be off, as well?
?</TD></TR></TABLE>

Correct me if i am mistaken, but i was under the influence that the secondary 02 sensor was mainly for emmisions reading reasons, not just for the ECU, but for state inspection as well. I have never had any difference in feel with or without it ( besides a CEL) in all my time of working on honda's. Just my $0.02

perseverance

i redid my entire exhaust and installed a skunk2 testpipe along with 2.5 mandrel bent exhaust all the way back on my 94 ex. still on stock motor.. getting ready to boost it. but mine makes a back fire sound when i shift. only when i'm revving higher than normal... like 6k,6.5k. i think this is normal tho

slowcivic2k

The secondary O2 is only present to monitor the efficiency of the Catalyst, if what you said was the case, all OBD1 cars would have this as well.


Most OBD2 sensors added to Honda's were emissions related, such as the Second O2, for catalyst monitoring, the CKF sensor, to precisely determine misfire and base corrections off of it, and the fuel tank pressure sensor and advanced purge system, to control evap emissions.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97Ej6mike &raquo;</TD></TR><TR><TD CLASS="quote">

Correct me if i am mistaken, but i was under the influence that the secondary 02 sensor was mainly for emmisions reading reasons, not just for the ECU, but for state inspection as well. I have never had any difference in feel with or without it ( besides a CEL) in all my time of working on honda's. Just my $0.02</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">The secondary O2 is only present to monitor the efficiency of the Catalyst, if what you said was the case, all OBD1 cars would have this as well.


Most OBD2 sensors added to Honda's were emissions related, such as the Second O2, for catalyst monitoring, the CKF sensor, to precisely determine misfire and base corrections off of it, and the fuel tank pressure sensor and advanced purge system, to control evap emissions.</TD></TR></TABLE>

Ahh, thanks for the correction.

I knew about the emissions checks - but I was under the impression that the secondary O2 made fuel trim adjustments much like the primary.

Thank you.

97Ej6mike

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">
but I was under the impression that the secondary O2 made fuel trim adjustments much like the primary.</TD></TR></TABLE>

I have heard of such a thing through my time of meeting other ppl with honda's and working on other cars with new people, and car meets. Some have claimed that there should be a certain fluctuation (frequency) between sensor 1 and sensor 2, that monitors whether or not the fuel input is correct ( too rich or too lean). I cant say anything for sure if that is true, but as i have stated before, i have had no differences in any way, either with or without the secondary sensor being present, for all i know, its just an OBD2 regulation for state emmisions reading.

slowcivic2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97Ej6mike &raquo;</TD></TR><TR><TD CLASS="quote">

I have heard of such a thing through my time of meeting other ppl with honda's and working on other cars with new people, and car meets. Some have claimed that there should be a certain fluctuation (frequency) between sensor 1 and sensor 2, that monitors whether or not the fuel input is correct ( too rich or too lean). I cant say anything for sure if that is true, but as i have stated before, i have had no differences in any way, either with or without the secondary sensor being present, for all i know, its just an OBD2 regulation for state emmisions reading.</TD></TR></TABLE>

It does make that correlation yes, but not for fuel trim control, but to compare the Primary (raw exhaust) to the catalyzed exhaust (Secondary) to determine catalyst efficiency.