N1 Downpipe Question

[xrobbx03]

I have a N1 downpipe and exhaust on my 97 gst. It throws a cel because of the rear o2 sensor. I need to pass emissions this month so i need to get a o2 down there somehow. My emissions is done by obdII. Is there a way to get an o2 sensor installed on my down pipe so i dont throw a cell or do i need to add a cat too.

Actually on dsms is the o2 in the cat itself or on the exhaust piping somewhere.

 

[iceman21221]

The second o2 sensor should be right after the cat. if there is no cat then it should be about in the middle of the car in the exhaust. The first 02 sensor is of course right after the turbo. Some people have used a few electronic parts and created an 02 sensor delete. Mabey someone installed the 02 sensor delete on your car before you bought the vehicle.

 

[xrobbx03]

yeah i bought the car with the downpipe on there and theres been a cel on every since. I was to fix it lagit without any fake o2 simulators. How can i do this.

 

[sheldon]

weld a bung on the d/p and install the o2

 

[TrystanGST]

yeah i bought the car with the downpipe on there and theres been a cel on every since. I was to fix it lagit without any fake o2 simulators. How can i do this.

I run 3" N1 turbo back without a cat as well. If you put an O2 sensor in the exhaust without a cat, you will still be throwing a CEL because the O2 sensor will get fouled. There are really 3 options to pass emissions:
1.) get the O2 and a high flow cat.
2.) wire up a simulator (easy and like 10 dollars in parts)
3.) get DSMLink and laugh all the way to the emissions facility.

I have the parts for 2, but I just got Link so I will probably just do 3.

 

[xrobbx03]

Is it ok to have them cut out a section of the downpipe to put a cat there and just have them weld it up?

 

[DGajre777]

Is it ok to have them cut out a section of the downpipe to put a cat there and just have them weld it up?

Yes, dammit, yes.

http://www.dsmtuners.com/forums/showthread.php?t=242529

 

[kawboy]

I run 3" N1 turbo back without a cat as well. If you put an O2 sensor in the exhaust without a cat, you will still be throwing a CEL because the O2 sensor will get fouled. There are really 3 options to pass emissions:
1.) get the O2 and a high flow cat.
2.) wire up a simulator (easy and like 10 dollars in parts)
3.) get DSMLink and laugh all the way to the emissions facility.

I have the parts for 2, but I just got Link so I will probably just do 3.

What do you do with DSMlink? BTW, you can pass emissions with no cat?

Thanks

 

[TrystanGST]

DSMLink has the option to "ignore" certain types of CELs. From the DSMLink page:

"DSMLink also provides a way for you to not only view the current set of diagnostic trouble codes (DTCs) being reported by the ECU, but also to disable certain ones as well. This is a handy feature when you know full well that certain codes are being thrown for bogus reasons or that you just don't care about them. The dialog shown below is used for this purpose."

So if you check the oxygen sensor it will no longer throw O2 error codes.

And without Link, 96 and up cars (OBDII) can still pass with the simulator because they are tested for codes only. 95 or older cars (OBDI) will not pass, nor will the 96 and newer if a sniff test is involved.

 

[Travi2506]

If you know anybody with a logger you can just clear the codes on your way to the emissions place... I don't have a cat on my car and it throws a code for "catalyst system efficiency for bank 1 is below threshold for the current engine operation conditions." (P0420)... So I don't see how moving the rear o2 sensor would change the conditions?

 

[TrystanGST]

I'm not sure what you mean by moving it. As long as the rear O2 sensor is not sitting behind a cat you will see that error code. You can clear the code with a scanner, but it comes back fairly quickly. I gave up on that because it would be back within ten minutes of clearing. I suppose you could have him clear it right before you got there and cross your fingers, but I would just wire in the "simulator" and not have to worry about it. This only applies to 96 and newer cars of course.

 

[iceman21221]

i dont know why so many people have trouble with the exhaust. i have a 98 with 3 inch turbo back with no cats. i have both the front and rear 02 sensors still in the car and i dont get a CEL. as a matter of fact its been done like that for over 2 years and i never fail at emissions. i might just be getting lucky. i even run leaded race gas 110, and still no problems.

 

[TrystanGST]

Well I know my rear O2 is not happy mainly because it's not there. Well it's filling the hole, but we cut the wires to get the stock exhaust off, and never re-wired the O2 when we put the N1 on. I'm not sure how you are not getting a CEL. Maybe your car just runs really clean? My understanding is that the car looks at the value of the 2nd O2 compared to the 1st O2 to determine when your catalytic converter is failing. So obviously if you had NO cat, it would throw a CEL stating that your cat was dead.

 

[DGajre777]

I run 3" N1 turbo back without a cat as well.

I don't mean to burst your bubble, but the N1 downpipe is not 3".

 

[blackbyrd]

I don't mean to burst your bubble, but the N1 downpipe is not 3".

Yeah. I guess what he meant was a 3" flex-back. haha. It's 60-80mm

 

[TrystanGST]

I don't mean to burst your bubble, but the N1 downpipe is not 3".

Yeah, you're right. It was just easier to say 3 in turbo back than not-3-inches-to-the-flex-than-3-inches-the-rest-of-the-way-back

*edit* besides I don't think my 130k mile T25 cares about those 20mm....

 

[xrobbx03]

I know that my N1 is 2.5'' at the inlet and 3in at the outlet on a 2g FWD am i right.

 

[blackbyrd]

Yes, that was already stated.