02 Sentra DC Sports Header help

[PacoBJuarez]

I was told by a shop that they could not install the DC Sports header because it removes the cat. I thought it only removed the pre-cat. What's the deal?
Modified by PacoBJuarez at 12:41 PM 1/29/2008

[D3stro]

It's because the DC header is a 4-2-1 piping style. Yes it remove the precat that is on the exhaust mani, and the DC header got the mid-pipe section on it too. The mid-pipe section got the main cat on it.

It's the red part that is remove with that header too.

On that header, you got one bung for the first O2 sensor. For the second o2 sensor, you must have an o2 sim or you'll get an SES light. For o2 sim, you can got for an electronic type like a Casper, or a mechanical one that act like a spacer for the o2 sensor to help it to be out of the exhaust flow so it should get reading that everything is just fine.An mechanical o2 sim look like that, you can get those for cheap on Ebay or make one.

[PacoBJuarez]

That's what I thought, that shop was stupid. Ok, thanks. Hopefully I'll find someone to do it that knows what they're doing. I still don't really understand the stuff about the o2 sensor, but maybe they will.

[nametakennow]

Most aftermarket midpipes do NOT replace the cat, they replace the stock midpipe, which ends at the cat.

I think your shop is retarded.

[PacoBJuarez]

They are retarded. I'll find someone else to do it. Just not easy to find good people to deal with aftermarket parts in my neck of the woods.

[D3stro]

That's what I thought, that shop was stupid. Ok, thanks. Hopefully I'll find someone to do it that knows what they're doing. I still don't really understand the stuff about the o2 sensor, but maybe they will.

The goal of the o2 sensor is to be sure that combustion of the mix of gaz and air get correctly done and the emssion of theses gases. The catalytic converter is there to reduce some toxics gases such as hydrocarbon, carbon monoxide and nitrogen oxydes. For the first 2 gases, the cat does a oxidation, separates them in nitrate or oxygen for example. So the second o2 sensor is after the cat. If you remove the cat, the o2 sensor gonna send a signal to the ecm sayin': ''there's somethings wrong in emissions of gases''. So appears the SES light in you cluster. It can results in bad MPG, maybe affect performance of the car. So with an o2 sim this gonna make believe to the o2 sensor that everything is all right. The way the mechanical o2 sim works is that it move the tip of the o2 sensor away from the exhaust flow, so it will get a good reading all the time.

That's pretty much about the o2 sims, hope it enlight you about their useful way.

[PacoBJuarez]

The goal of the o2 sensor is to be sure that combustion of the mix of gaz and air get correctly done and the emssion of theses gases. The catalytic converter is there to reduce some toxics gases such as hydrocarbon, carbon monoxide and nitrogen oxydes. For the first 2 gases, the cat does a oxidation, separates them in nitrate or oxygen for example. So the second o2 sensor is after the cat. If you remove the cat, the o2 sensor gonna send a signal to the ecm sayin': ''there's somethings wrong in emissions of gases''. So appears the SES light in you cluster. It can results in bad MPG, maybe affect performance of the car. So with an o2 sim this gonna make believe to the o2 sensor that everything is all right. The way the mechanical o2 sim works is that it move the tip of the o2 sensor away from the exhaust flow, so it will get a good reading all the time.

That's pretty much about the o2 sims, hope it enlight you about their useful way.

Thanks for the info man! I understand a little better now.

But, since the header only removes the pre-cat and keeps the cat, I don't need one of those sims, right?

[VMPhil]

yes you will need it because the sensors are placed before and after the Stock precat and since you are removing it you are throwing off the sensors reading.

[PacoBJuarez]

Ok, so a shop wants to charge me around $320 (estimate) in labor to put in the header. That's total crap. I'm thinking about having a couple of friends do it. Is it really difficult?

[nametakennow]

A torque wrench, the right size socket(s) and a little time. 8 nuts on the mani studs, few bolts at each end of the midpipe. You may need some brake cleaner or some other solvent to get the nuts/bolts loose.

[PacoBJuarez]

I thought it was simple but just really time consuming. Thanks!

Any specific things I should know to look for or check for while we're doing it or afterwards to make sure they didn't screw anything up?

[nametakennow]

Not much you can screw up unless you break/strip a stud (which would take some effort), damage the O2 sensors, or shove something into the exhaust ports on the block.

Make sure you get a solution to that 2nd O2 sensor and you're clear.

Oh, and it's not all that time consuming. Should take ~30min for a couple of average car guys.

[PacoBJuarez]

What's your recommended solution for the second o2 sensor if it's a couple of average car guys doing the install?

[nametakennow]

If you've got some wiring stuff, move it back, but otherwise just do the defouler trick.

If I recall, the wires on the sensors are hard to solder, so the defouler trick is probably easier.

[PacoBJuarez]

It comes with an o2 cable extender. I think I'm going to go that route since (after reading through them) the instructions are pretty detailed and mention repeatedly exactly what to do with the o2 sensor.

[desole1019]

alrigth so i have the same problem with my DC header......one thing that im worried about is if i will pass emissions on it?...and about the sim thing if i have the O2 sensor extension then i shouldnt need that right? and i dont have gaskets the the header should come with since i bought it used...can i use my stock ones or do i need to buy perfromance ones?

[nametakennow]

If you move the 2nd O2 sensor behind the cat, you will not get any ECU codes and you will pass emissions.

If your state does a thorough visual check, they may take issue with this method. If this occurs, try the de-fouler trick.

[desole1019]

ok i still dont think im completely understanding.....the header has a secong bung were the o2 sensor would go approximatly were the precat would be right?

i have an O2 sensor extension.....so as long as that O2 sensor goes in the second bung on the header then i should be ok?

and one more thing, kinda stupid ? but i dont know much yet ...im new to this.....how many O2 sensors does the 02 SER have and were are the stock ones placed?

[nametakennow]

The header has a bung near where it meets the block. Put the first O2 sensor in it.

If there are any other bungs on the header or midpipe, plug them.

Use the wire extension to put the second O2 sensor behind the cat. Stock, it is in the stock midpipe underneath the engine, but before the cat.

There are 2 sensors. Stock, the first one is in the exhaust mani just after it mates with the block, right above the precat, which is integrated into the stock exhaust manifold/header. The second, as stated above, is in the midpipe, long after the precat, but before the cat.

The idea is that the first sensor takes a reading for engine management, the second takes a second reading after the precat to ensure that the precat is functioning and the air moving down the exhaust stream is cleaner. When you put in a header, you have to trick the second sensor into reading cleaner than the first sensor so that the ECU thinks there is a precat and it is doing its job. Thus, you move it behind the cat to accomplish this trickery.

[desole1019]

ok thanks alot makes sense now......now going out of the subject....wana ask you something else ....you seem really knowledgeble .....im looking around for an exhaust....i want something not too "ricee" or loud....i want something more mellow and deep...but not raspy....i was looking at a couple options a WS2 apexi, evo 2, or Borla.....wat do you recomend....and by adding the header, AEM CAI, and the exhaust how much WHP would i gain?

[desole1019]

so tehn just to be clear as long as i pu the two O2 sensors in the two bungs on the header then i should be ok...i dont have to drill no holes or change anyhting else besides just adding the O2 extension lead for the second O2 sensor right?

[nametakennow]

No, re-read my post. ONE sensor in the header, ONE after the cat, all other bungs plugged.

In order to put the second sensor after the cat, you'll need to have a bung put in. ~$50 at an exhaust shop.

As for exhaust, check the Table of Contents and find the exhaust thread, we have a few clips in there. I'm a fan of the BRM, but the WS2 and Greddy exhausts also get good reviews. The NISMO is good as well, but generally very expensive. If Borla makes one, it probably sounds pretty decent.

[SPECV2002moded]

hi guys testing new account

[SPECV2002moded]

Hi i don t know for other years spec-v but for a 2002 ... the answer is YES INSTALLING A DC RACE HEADER 4--2--1 WILL REMOVE ALL THE CAT INSTALLED ON THE CAR BY NISSAN.....If u want know what to do ... post and i will telll u alll u need to know cause i have DC race header on my 2002 spec-v.