5th gen dd

2001 GLE A/T

I just got done gutting my front precat and when I went to move onto the rear I realized that I do not have a precat on the rear bank. There is just a hollow downpipe that continues into the Y section. I know that I need to install spark plug anti-foulers in the sensors directly after the precats and not before, but with the car only having a front precat do I need to install an anti-fouler on the secondary O2 for the rear bank since it's still considered downstream and post precat?

Here is a diagram of my setup:

I underlined the pre and main cats and circled the area in question.

Here is the setup that I assumes uses a precat at each exhaust manifold:



And here's a few pics:

Shot of the Y pip section.


This is the sensor coming off the back bank that's right before the Y that I am unsure if I need to add the anti-foulers to. If I'm not doing anything upstream of it, I'm guessing I should leave it alone.

For those of you that are unfamiliar, the anti-fouler tricks the ECU by falsifying it's reading and killing the SEL light you get from gutting cats or aftermarket headers and serves the same purpose as an O2 sim. I was changing out my motors mounts and had been toying with the idea of doing this for a while and figured I might as well while I was there and had the engine cradle out.

I spent some time searching but could only find vague mention of using the anti-foulers and nobody specified where to install them in this situation to prevent an SEL light, as well as, confirmation that some vehicles were produced without a precat on the rear bank.

tcaughey

iTrader: (6)

I've looked into it and found this a while back:

http://forums.evolutionm.net/evo-how...ouler-how.html

It's more of a anti-fouler how-to rather than an answer to your question. I'm sure someone else will chime in and give you your answer.

Grand_hustle17

iTrader: (22)

I'm assuming this is to avoid codes.... There are more n more maximas showing up with no cats and have no CEL nowadays and they aren't using any o2 Sim nor foulers...

TunerMaxima3000

iTrader: (4)

-All 5th gen Maxima's come with 2 precats from the factory.
-The 2000/2001 Has the rear (right bank) Precat built into the y-pipe
-You should only need O2 sims/anti foulers if you delete both cats. If you only delete one, you just move the one O2 sensor next to the other post-cat O2, this causes both sensors to read 'treated' exhaust gas based on the one working Cat, thus no code.

Again, you have 2 precats. The front one is a separate unit, and the rear one is built into your y-pipe. Replacing it with a better aftermarket Ypipe is one of the best bang/buck mods you can do on your 2000/2001

Grand_hustle17

iTrader: (22)

Fact: you dont need o2 sims nor foulers to prevent CEL...

TunerMaxima3000

iTrader: (4)

I read constantly of people with secondary O2 codes because of precat guts, deletes, headers, etc.

Constantly.

VQMagic

iTrader: (1)

All ears here. My car has the code since I've had headers almost 4 years ago. The non-fouler trick didn't work for me either

nelledge

iTrader: (6)

Incorrect. I'm ok with you saying some don't need it, but the large majority that delete their precats do.

TunerMaxima3000

iTrader: (4)

The normal procedure is silly, and is hit/miss.

If you want it to work do it like this:



This will be harder to find but will work.

If you cant find one like this you can always make one out of steel pipe. One 1" nipple, a 90* elbow, and then the normal non-fouler extention.

And point the 90 back toward the origin of the exhaust so even less exhasut goes in

TallTom

Or just buy this and call it a day.

http://www.summitracing.com/parts/vpe-11621

TunerMaxima3000

iTrader: (4)

Yes that would be your average run of hte mill cheapo non-fouler. That is exactly what I said doesn't always work, or works intermittent. Because a whack of gases still get in at the O2 sensor, especially on some engines/chassis.

The 90* is pretty much a bulletproof solution to combat it.

TallTom

The one I posted also has the caps to limit the amount of exhaust, unlike a normal non-fouler.

Galactica

iTrader: (5)

I'm trying to picture how this works but I just can't see it in my mind's eye...

5th gen dd

Is there anything that can be done with this version of precat to gut it? I didn't see any way to access it other than through the O2 bung maybe. With that in mind, IF I can't gut the rear at all, will it affect the cars performance having the front done and the rear as is? It seems like there would be a difference in flow that would upset the balance of the motor. On the good side, the front seemed to be in mint condition and the car only has 78k miles on it so I doubt the rear is clogged.

Looking at the Cattman site I see they offer 3 different versions of Y pipe. Which one is the correct model for my application?

CA/NLEV spec or Federal?
http://www.cattman.com/prod_exhaust.html

As long as it's under $500 I prefer to go that route anyways. I was suprised at how easily everything came apart. I'll only need to drill out a few studs on the y pipe heat shield and cut the studs for the flange going to the resonator since they were too rusty and a 6 point 14mm would just spin. I may try torching them some more and hammering 13 mm impact socket on and see if that does the trick.

For now I think i will just break the O2 sensors loose so that they are easier to mess with when everything is reassembled and deal with any codes as they arise. Any recommendations on a Y pipe other than Cattman's? I always like an excuse to do an upgrade.

TunerMaxima3000

iTrader: (4)

Normally the O2 goes right into the exhaust stream.
Most O2 de-foulers put a 'spacer' in so that the O2 mounts out of the exhaust stream.
This 90* moves the O2 out of the exhaust stream, an around the corner, back the other way. This means that the only way signifigant exhaust is going to get at it is if there's crazy backpressure in the exhaust and it surges back into the O2 sensor. Not likely to happen unless you have an engine that's cammed to heck and pushing some serious air. Or have a crimped exhaust pipe or plugged Cat.

TunerMaxima3000

iTrader: (4)

I don't knwo if anyone has tried, but if $500 is a resonable budget just buy the Cattman ypipe.

You want the Cali spec 2001 version. If you can't get one (likely), then I think Warpspeed is your next best bet. Do your research.

As for having 1 cat eliminated and not the other, I agree with your theorum, however, it's common practise to do this. Guys have been doing this to these engines for a LONG time by just replacing the Ypipe and not touching the front PreCat.

If you're serious about all that jazz and want to even things out, gain some ponies, etc, buy headers.

Mr. Blue Sky

iTrader: (1)

This is true for the non-fed spec maximas(very few are fed-spec it seems). My 2000 fed spec came with no precats(stock y-pipe went directly to each header. only has the main cat). The weird j-bend anti-fouler pictured below will probably give you the best results if you are going for getting rid of codes. The warpspeed would be a cheaper y-pipe to get. they don't seem to have the flex pipe issue that used to occur in the past.

5th gen dd

Thanks for the responses so far. After closer inspection, the outer weave of my flex pipe is already deteriorating, I think I am going to go for the Warpspeed unit and order it today. The rain hasn't been bad so the MR2 can spend another week parked out of the garage while I'm waiting for the y pipe to show up. My only concern now is if I am going to be happy with the sound of the exhaust after this is done. I have a feeling I'm going to have a full exhaust system before this is over with. I've seen some complaints about raspiness on here after adding the Y pipe to a stock system. So much for keeping this car stock like I said I would when I got it. Just can't leave things alone.

Tuner, any idea where to find that elbow setup or what it's called? A google search for oxygen sensor relocation comes up with either something similar to the anti-foulers or parts for specific exhaust systems. Worst comes to worst, it doesn't look too hard to make.

TunerMaxima3000

iTrader: (4)

Fed spec has them both built into the Ypipe. So replacing the Y pipe replaced both Precats.

They still have precats.

5th gen dd

I went ahead and ordered the warpspeed y pipe. I called them before placing the order and they said all materials are in stock and they should have it assembled by the end of next week and arrival should be by the end of the following week. So looks like I'll be driving the MR2 for a bit longer than expected. I'm glad I fixed the A/C last month.

After doing some research and checking prices and availability on headers I decided to hold off on on this for now. Once I finish school at the end of the year I'll have more financial freedom and probably do a full length Cattman system at that time.

Mr. Blue Sky

iTrader: (1)

when I replaced my stock y-pipe I saw no such precats(unless they were really tiny ones, or maybe different style). just straight through pipes. I guess I was expecting the large style of pre-cat.

well, the point is, I replaced it with a warpspeed y-pipe and absolutely no codes sprang up. ever.

MaxFiyah

omg this thread just got me all excited cause i was sad that i was going to have to put a cat on my car since i have a precat delete and i didnt want to lose power just to pass inspection

5th gen dd

Just so you know the route I went. I picked up a dual sim chip from 3sx performance and haven't had a problem since. Never once saw code. I depinned the plugs going to the o2 sensors and spliced the wires in there because I didn't want to cut into the factory wiring. After running the wires into the dash to protect the chip from engine heat and relooming the harness at the plugs, you would never know anything was modified.

Oh... and Warpspeed took 3 weeks longer than they said they would to get the pipe to me.