I searched and it looked like everything about back pressure was for performance.

I have a '95 civic with B18B, intake, headers and 2 1/2" exhaust. I am trying to get it BARed and one of the things that i've heard is that the I/H/E can be causing no back pressure which is making that cat not work as effectively. Is this true? also would back pressure have anything to do with my cat not heating up as quickly? Thanks for any information

 

Well whoever gave you that info.....Is very correct.

You put it exactly the way I would of. Usually a little extra pre-conditioning would get you thru however the ref is not going to help you there.

You could have a smaller resonator put on for the test. Stock exhaust is 1.75 on my SI I went to 2.25 and almost over did it and I just barely pass.

I wonder if a restrictor plate after the cat would work? Just thinking out loud...

 

What were your last emissions results?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 &raquo;</TD></TR><TR><TD CLASS="quote">What were your last emissions results?</TD></TR></TABLE>

My results at 15mph have been NOX at about 1500 and HC at 125 and the max is 7XX and 89. The strange thing is when my car runs for a while the numbers drop a lot. And yes before the test i drive the car a lot.

 

Does anybody know if back pressure would cause the cat to get hotter faster?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike03,95civic &raquo;</TD></TR><TR><TD CLASS="quote">My results at 15mph have been NOX at about 1500 and HC at 125 and the max is 7XX and 89. The strange thing is when my car runs for a while the numbers drop a lot. And yes before the test i drive the car a lot.</TD></TR></TABLE>
Can you please post the entire emission results? All numbers are relevant.

Also, when you say the numbers drop a lot after driving, I assume you mean they were higher before?

 

I don't have the numbers in front of me but i can post them later. And what i ment from before is when i took it to a shop and had it running on the dyno while they were looking for a cause for the high numbers the numbers droped off a lot. Also it only fails the 15mph not the 25mph.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike03,95civic &raquo;</TD></TR><TR><TD CLASS="quote">I don't have the numbers in front of me but i can post them later. And what i ment from before is when i took it to a shop and had it running on the dyno while they were looking for a cause for the high numbers the numbers droped off a lot. Also it only fails the 15mph not the 25mph.</TD></TR></TABLE>
Ok thanks.

I guess I'm still a little confused. Were those numbers you posted the lower numbers after car had been running for a while or the high numbers?

 

They are numbers from when the BAR did the emissions test.
MAX Allowed for HC at 15mph is 89 but I measured 128
MAX Allowed for NOX is like 750 but I measured like 1500.

(drove the car hour and 1/2. then they did there inspection so car was off for 15-20min. then idled for like 5min.)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 &raquo;</TD></TR><TR><TD CLASS="quote">
Can you please post the entire emission results? All numbers are relevant.</TD></TR></TABLE>

Sorry this is not in picture form
(max) is max allowed to pass (meas) is the amount measured

15mph,25mph
%co2 = 14.37,14.83
%o2 = 0.44,0.04
HC
max=89 meas=105,max=54 meas=54
CO(%)
max=0.53 meas=.49,max=0.51 meas=0.13
NOX
max=708 meas=1411,max=746 meas=247
FAIL,PASS

hope this helps

 

How old are your plugs/cap/rotor/wires?

What emissions equipment do you have, and do you know if they are working properly? Have you tested your o2 sensor?

The 25mph run was really not that bad. I just looked at my last emissions results and realized that your standards are a lot more strict. My car would have failed in CA...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ddd4114 &raquo;</TD></TR><TR><TD CLASS="quote">How old are your plugs/cap/rotor/wires?

What emissions equipment do you have, and do you know if they are working properly? Have you tested your o2 sensor?

The 25mph run was really not that bad. I just looked at my last emissions results and realized that your standards are a lot more strict. My car would have failed in CA... </TD></TR></TABLE>

my plugs are new, cap and rotor i don't know, and which wires are you talking about? I took my car to a CAP station and they checked the O2 its working but supposedly my O2 readings are a little slugish but i think the guy is just looking for an excuse to why the car is not passing after there recommendations. oh yeah the O2 sensor is about 4 months old. Other than that all emissions equipment is hooked up correctly.

I know i don't get why the 25mph is good and not the 15mph. Yeah CA sucks

 

Well I was able to get a stock exaust pipe and cat off another civic and tomorrow its back to the BAR so will see how much the stock piping helps.

 

Good luck buddy and hope it passes. Let me know how it goes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97Integra &raquo;</TD></TR><TR><TD CLASS="quote">Good luck buddy and hope it passes. Let me know how it goes. </TD></TR></TABLE>

yeah i will

 

Well i failed but i think the cat i had on this time is dead. i don't think i would of passed any way. I asked the BAR tech about the back pressure thing and he said that it would make a difference.