Jump to content

Pre-Cat On Your Wd21


Precise1
 Share

  

33 members have voted

  1. 1. Do/did you have a stock pre-cat?



Recommended Posts

Ok, I have 2 95XE pathfinders, both have a pre-cat. This is specifically for warming up, it gets to temp faster than the 'normal' cat so it helps cut emissions from a cold start. Not a bad idea, too bad it is a small diameter (1.75")rusted piece of crap.

 

I'm installing headers this weekend and would like not to have it re-installed, but still need to be smog compliant.

The Thorleys end in a 2.25" flanged tube, I'm going into a 2" high flow cat and then 2.25" the rest of the way.

 

My questions are does your pathfinder have a pre-cat stock? What year is it and where do you live.

Is this something specific to snow country? (one pathy was from Rodchester, NY and the other from Pensylvania)

Do you have aftermarket headers and are smog compliant? What is your set up?

 

Thanks for the input...:shrug:

 

B

Link to comment
Share on other sites

  • Replies 61
  • Created
  • Last Reply

Top Posters In This Topic

I'm in mn and I have a pre cat(I also have pet cats if that counts?),but we dont have any smog rules so I can hack them off if I really wanted to.If your new cat is good then I dont see how it will be any less efincesent then the ones on it already.

Link to comment
Share on other sites

I DID have a pre cat on my current 95. I was told it was for California emissions (yes, even some Canadian models conform to those standards) and was not necessary to pass emissions testing here in Ontario. It was removed, and I never had an issue with Emissions tests.

 

That said, I'm not sure how much more stringent the smog tests are in Cali, so I don't know what to advise you in that regard.

 

My old truck (also a 95) did not have the pre-cat. :shrug:

Link to comment
Share on other sites

All 3 of mine had pre-cats when I got them. I got a whole new exhaust on the gray 95 which included a new cat and there was only one this time. Haven't had it through emissions since I got it (the truck, near the end of the year) but we will see next year.

 

Though I noticed on the emissions test report for my dads r50 that here they tightened up the emissions requirements. :ar15:

Edited by adamzan
Link to comment
Share on other sites

Thanks for the input so far, but I'd love to hear more. It doesn't make sense that the pre-cat is a California spec yet all 3 of Adam's have it (not to mention my 2 east coast vehicles). That's more coincidence than I am willing to accept. I'm almost wondering if it isn't a cold weather option as it is directly related to start up and catalytic operating temperature.

 

I just talked to the local Stealership parts department and asked him if the pre-cat was required, was it available and how much does it cost. He said that the 95 only shows 1 cat according to their parts list.

 

I've decided that I am going to leave that piece out of the system and only run the new cat. I'll find out next year (smog year) if there is an issue. If there is, I'll just have a new section made with the pre-cat and install that (flange connections). :shrug:

 

B

Link to comment
Share on other sites

Looking at the Nissan4u website, it looks like all Pathfinders over there came in 2 different emissions specs, Federal or California. Perhaps people could order either from the dealership anywhere in the country.

Link to comment
Share on other sites

Hmm, useful site!! What you say makes sense Dave, but from their diagrams, neither Federal or Carfornia shows the precat, unless I am misreading. :shrug:

 

If it was easy, that is only until I get a hold of it...

 

B

Link to comment
Share on other sites

When I was looking and could only find 4 doors, I don't ever remember seeing any pre-cats on them. Think it would have stuck out when I was frame inspecting (since I went from bumper to bumper on both rails when I looked). Neither of my 88s have one either, nor any of my old HBs(though they were all some form of 4 cylinder z or ka) As far as I know only the one I drive now is from somewhere other than PA.

Link to comment
Share on other sites

I am in the same boat as Simon, although i have headers on mine. I passed our emissions test by a hair. We'll see how it goes next year :ill:

Edited by nige
Link to comment
Share on other sites

I guess this is where I should chime in. My 95 came with the pre-cat. I bought it here in Florida, but don't know if it originated in some other state (I don't think so.)

 

It doesn't show on the exhaust diagrams directly, but it is definitely orderable. (Your stealership people are morons) If you use courtesy's website and follow the link on the part where the pre-cat should be, you will find the different parts that can go there by year, trim, & drive style. The expensive ones are the pre-cat ones.

 

I can tell you my cat story:

 

Step1: gut & sleeved main cat...Result = Kick Ass. Felt like I gain 20hp at least.

Step2: gut pre-cut...Result = loss of low end torque. Not terrible, but noticeable.

 

I have never been sure if the reduction in torque was due to the loss of back pressure or the bad flow characteristic of the open area of the pre-cat. BTW, adding the Borla CatBack without Steps 1 & 2 did nothing to improve performance. If I had done Step 1 & 2 at the same time it still would have been a major improvement over stock set-up.

 

Personally, based upon my experience I would do what you plan to do to the exhaust and leave the pre-cat in place. If you don't think you are getting the power improvement that you should, you can always pull it out later and have an exhaust shop fab up a piece to go in its place.

Edited by andreus009
Link to comment
Share on other sites

Good input, thanks!! Is that why you needed that section of pipe?? :D

 

Well, I'm going to leave it out (for now) and count on the high flow cat for the back pressure (not gutted, like yours). Hoping for the happy medium?? :shrug:

But yeah, if I have any issues, I will simply have another pipe section fabbed that has it included. Pretty cheap, really, and may make for an interesting comparison. :shrug:

 

B

 

:shrug:

Link to comment
Share on other sites

Good input, thanks!! Is that why you needed that section of pipe?? :D

 

Yep, that is the reason. Easier than having a custom pipe fabbed that may or may not work. I should have scavenged one from J/Y but been too busy and/or lazy.

 

Adding a high flow cat back into the system was my other thought, but hadn't pursued it. I imagine whatever you do will be better than stock, so you going to get an improvement. Good luck and let us know how it turns out.

Link to comment
Share on other sites

  • 3 weeks later...

89 cali model. no pre-cat ever. Thorleys and magnaflow cat (installed in the last 3 years) are 50state carb but I have not had to test since I am military outside of Cali. If I had to guess I think it would pass. Its last test was pretty ok, Little close on the HC content but I'm guessing the new cat prolly reduced that...

Link to comment
Share on other sites

  • 4 weeks later...
  • 6 months later...

thanks Precise for finding this thread and now to revive it:

 

94 SE from Florida as far as I know, no pre-cat,also my 87 Hardbody with the VG30i bought new in NY no pre-cat

Link to comment
Share on other sites

Pre-cat on my 1995 here in Washington. Car originated here, so not sure if they just put one on cuz I was close to cali or what?

 

Apparently it's clogged, because the stealership says I am getting a ton of back pressure on my engine which is "supposedly" the cause of my bad gas millage. I passed emissions last month, now I am going to take the pre cat and cat out and slap in a Magnaflow high flow cat. Currently taking estimates on a custom exhaust system.

 

Let me know if it affects your emissions testing, I know cali emissions is tougher than we have in WA... So if you pass then I will :)

 

-Mike

Link to comment
Share on other sites

Yep, mine had a pre cat despite nobody believing me...its gone now though...pile of junk if you ask me...truck actually runs BETTER without it.

 

Here is a pic....

factoryexhaust.jpg

Edited by tmoore4512
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share


×
×
  • Create New...