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My girlfriend was considering getting some test pipes for her 04 after installing the borla true dual, to make it just a bit louder. My concern was regarding the OBDII computer, and emissions compliance. NOTE: I KNOW TEST PIPES ARE NOT EMISSIONS LEGAL. However, OBDII vehicles are not required to have dyno testing or an actual sniffer test to pass emissions - all they do is hook up a scan tool to your ECU and pull any codes, sensors reading out of normal parameters, etc. Will the computer throw any codes from having the cats removed?

Before I bought my trucks, I had a 94 firebird formula (LT1), and after replacing the muffler with a straight pipe, I got bored with the sound and gutted the cat. I did a little homework beforehand to see if it would affect the way the car runs, and my research (and all my friends) told me that, since it was an OBDI vehicle, there was no O2 sensor after the cat, and the computer would not know the difference if I removed the cat. This was true. However, on OBDII LT1s and LS1s, O2 simulators (just a resistor in the post-cat O2 sensor) must be installed in the second O2 sensor circuit, sending the computer the voltage that an O2 sensor with a proper reading would send. They are required to "trick" the PCM into thinking that the cats are present and functioning as they should.

I haven't done any research on the 350z's fuel system and computer to see if such a modification is required, so I thought it would be worth asking. I was told that there is a sensor in or on the cat, but wasn't sure if it reads the o2 after the cat or before, and that would make the difference in whether the car runs like crap, overfuels, smokes, etc., or not. OBDII fbodies that didn't have O2 simulators ran poorly, if at all, so it is definitely worth looking into. Thanks in advance for your help!

- Bryan
 

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thats a pretty good ? you got there, it makes sense that it wouldnt matter if you had test pipes cause i always read that they dont throw check engin lights, and if it doesnt throw the ligght then it shouldnt matter, either way i have a hookup and i will be ordering my pipes in about a week so i will let ya know what happened, also i have a true dual borla catback and its just to quiet thats why i am doing test pipes.
 

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Originally posted by badass1g@Jun 29 2005, 12:36 AM
thats a pretty good ? you got there, it makes sense that it wouldnt matter if you had test pipes cause i always read that they dont throw check engin lights, and if it doesnt throw the ligght then it shouldnt matter, either way i have a hookup and i will be ordering my pipes in about a week so i will let ya know what happened, also i have a true dual borla catback and its just to quiet thats why i am doing test pipes.
[snapback]123685[/snapback]​

O2 sims take care of all
 

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some 04+ models throw codes. Mine does. I have reset the ECU many times and it always comes back. I am going to do the cheap mans method of installing spark plug foulers to fool the ECU.

Results to follow soon..
 

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Originally posted by ******* truck@Jun 28 2005, 11:10 AM
My girlfriend was considering getting some test pipes for her 04 after installing the borla true dual, to make it just a bit louder.  My concern was regarding the OBDII computer, and emissions compliance. NOTE: I KNOW TEST PIPES ARE NOT EMISSIONS LEGAL.  However, OBDII vehicles are not required to have dyno testing or an actual sniffer test to pass emissions - all they do is hook up a scan tool to your ECU and pull any codes, sensors reading out of normal parameters, etc.  Will the computer throw any codes from having the cats removed?

Before I bought my trucks, I had a 94 firebird formula (LT1), and after replacing the muffler with a straight pipe, I got bored with the sound and gutted the cat.  I did a little homework beforehand to see if it would affect the way the car runs, and my research (and all my friends) told me that, since it was an OBDI vehicle, there was no O2 sensor after the cat, and the computer would not know the difference if I removed the cat.  This was true.  However, on OBDII LT1s and LS1s, O2 simulators (just a resistor in the post-cat O2 sensor) must be installed in the second O2 sensor circuit, sending the computer the voltage that an O2 sensor with a proper reading would send.  They are required to "trick" the PCM into thinking that the cats are present and functioning as they should.

I haven't done any research on the 350z's fuel system and computer to see if such a modification is required, so I thought it would be worth asking.  I was told that there is a sensor in or on the cat, but wasn't sure if it reads the o2 after the cat or before, and that would make the difference in whether the car runs like crap, overfuels, smokes, etc., or not.  OBDII fbodies that didn't have O2 simulators ran poorly, if at all, so it is definitely worth looking into.  Thanks in advance for your help!

- Bryan
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The CEL that you get by removing the cats does NOT affect performance at all. It is merely a code to show that the cats aren't working.

That said, no o2 sim is needed. they are more $ and more work than is needed. The HELP! method is tried and proven to get rid the test pipe related CEL.

Get two packs of HELP! Nonfoulers - part number 42002 or 42009 (either will work) - these are readily available at autozone, checker, etc.
Drill ONLY 2 of the nonfoulers out with a 1/2" drill bit. Fit 1 NONdrilled fouler into each test pipe. Fit 1 drilled nonfouler into the previously installed undrilled fouler on each bank. Finally insert your o2 sensor into the drilled nonfouler and reconnect the wires. THAT IS IT.
 

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One of the questions he had that I would like to know is with test pipes, will the ECU run rich and start pouring black smoke out the exhaust? I know I've seen friends that have N/A imports that put in test pipes and they have black smoke. I don't want to have that **** coming out of my Z. Anyone got some answers?
 

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Originally posted by CodeRed30@Jul 2 2005, 02:20 AM
One of the questions he had that I would like to know is with test pipes, will the ECU run rich and start pouring black smoke out the exhaust? I know I've seen friends that have N/A imports that put in test pipes and they have black smoke. I don't want to have that **** coming out of my Z. Anyone got some answers?
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The ECU will not adversly affect fuel due to test pipes. The Z actually has a tendancy to run lean.
 

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Originally posted by CodeRed30@Jul 5 2005, 03:19 AM
OK then, no black smoke and no CEL with test pipes?
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No black smoke on all models:

03s and early 04s usually don't throw codes
04.5s and 05s usually throw codes, but the HELP! method (nonfoulers) is an easy fix - do a search on it.
 

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i will be putting on my test pipes on my 03 track edition, with a borla catback this thurs and i will post how it sounds and if any sel, i cant wait :)
 

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k guys, no cel light, install wasnt too bad, i have an exhaust leak from the rear section now so i will post later today after i fix that how it sounds, also i could actually tell a little bit of power gain, it revs faster :)
 

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Originally posted by TOYKILLA@Jun 30 2005, 01:54 PM
some 04+ models throw codes. Mine does. I have reset the ECU many times and it always comes back. I am going to do the cheap mans method of installing spark plug foulers to fool the ECU.

Results to follow soon..
[snapback]124673[/snapback]​


I did this fix, and it seemed to work for a day, the the CEL came back..
 

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Originally posted by TOYKILLA+Jul 8 2005, 10:43 AM-->
<!--QuoteBegin-TOYKILLA
@Jun 30 2005, 01:54 PM
some 04+ models throw codes. Mine does. I have reset the ECU many times and it always comes back. I am going to do the cheap mans method of installing spark plug foulers to fool the ECU.

Results to follow soon..
[snapback]124673[/snapback]​


I did this fix, and it seemed to work for a day, the the CEL came back..
[snapback]128641[/snapback]​



did you install them correctly? Most only put one nonfouler on each bank or drill all 4. Check to make sure you installed them correctly and that the CEL is actually a downstream o2 sensor related code:

o2sensor ->drilled nonfouler -> UNdrilled nonfouler -> test pipe
 

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yes they are installed correctly.. i reset the ecu by disconnected the battery because i could not get the other method to work. you think this has something to do with it?
 

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Originally posted by TOYKILLA@Jul 8 2005, 06:37 PM
yes they are installed correctly.. i reset the ecu by disconnected the battery because i could not get the other method to work. you think this has something to do with it?
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Maybe,

What yr car do you have? I have an 04.5 with no issues running the nonfoulers. I know of a few 05s that have done the HELP! method with success as well.

Didn't you just install a turbo kit? could it be something to do with that? get the specific code you are throwing and we can work from there.
 

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i have a 03 and i installed test pipes and three days later im noticing smoke out of exuast will this top or will i have to put my stock cats back on. the help method works no CEL??
 

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i have a 03 and i installed test pipes and three days later im noticing smoke out of exuast will this top or will i have to put my stock cats back on. the help method works no CEL??
That is normal. It needs to burn the oil layer from the pipes.
 

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at 1st it will throws out TONS of white smoke,then its just when you give it WOT. you should check out the wiki section of test pipes or type in test pipes in the search and look at a "pinned"
 

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NOTE: I KNOW TEST PIPES ARE NOT EMISSIONS LEGAL. However, OBDII vehicles are not required to have dyno testing or an actual sniffer test to pass emissions - all they do is hook up a scan tool to your ECU and pull any codes, sensors reading out of normal parameters, etc. Will the computer throw any codes from having the cats removed?


No one fully answered this one yet :p

Test pipes will or won't pass inspection with these cars? If they won't, how are test pipe users getting around this? Swapping cats in on inspection day?
Just curious.
 
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