Fink

OK guys, CEL came on about a month ago...pulled the code, bad cat., ordered a Magnaflow off EBay, had it put on. Light goes off for about a half tank, light comes back on, pull the code, bad cat., jack it up...the 4runner I bought that originally came from West Virginia was a Calif. emissions model. So it's got dual cats. I order another Car Sound cat, it comes, take it to Seeburg, they jack it up get ready to install it and tell me its not going to work. I guess the stock one has a prebent pipe or the actual cat is bent with like a 30-40* offset and they said the would have to move the stock location of the cat back about 4 inches to allow for the Car sound muffler and that its not a complete bolt-on. I couldn't really follow him, he had a thick Arkansan accent.

What do I do??? Do I see if I can find a cat that is made for the front position of the exhaust or what?

Fink

masterwacker

if you don't live in CA anymore forget one of the cats.

MTL_4runner

It is legal to remove the second cat as long as the vehicle no longer needs to pass CA inspection.
I would just run the new high-flow cat only.

Fink

The guy at Seeburg said that if the location of the converter moved that it might throw the 02 sensor off...is this true? Should I just have them cut the pipe off behind the front sensor and then weld on a new piece of pipe between the 02 sensor and the high-flow cat.?

Fink

Silver_Truck

I'd just run one like the others said...get a picture of a "regular" 3rd gen exhaust take it in and say thats what i want.

nrgetic99

I had a 99 with twin cats.

Just make sure you don't have an o2 sensor downstream of the cat then do away with it.

Seems like a really good time to get them headers you are dreaming of


David

mt_goat

nm....

MTL_4runner

The O2 sensors should be within 12" of the converter front and back.
If you take out one of the converters (I suggest the second one down), make sure to move the O2 sensor bung.

Fink

Ok so let me get this straight.

Right now I've got a pipe coming from the headers with a 30* bend downward towards the ground, the angled section is about a foot long and and then it's got another bend that is 30* to flatten it out and go straight back to the back of the rig. About 3-4 inches up from the final bend point there is the O2 sensor and then about 2 inches back from the final bend there is the cat. converter. So I should have them cut the section of piping that the O2 sensor mounts to, cut off the old cat, put new piping in from the old O2 sensor location to about 12 inches away from the cat. where the new O2 sensor location will be. Is that right?

So basically cut off all the old piping up until the highflow cat, move the 02 sensor closer to the rear end cat. converter and then I should be good to go.

Let me know if I have this all straigthened out, if so I will be going to Seeburg on Monday and getting it all done.

With only one cat. versus two will there be any noticeable difference in power or mileage? I'm not expecting any, I'm just wondering how it will affect it, other than that annoying orange light that is still on.

As for how new the 02 sensors are...I honestly don't have a clue. i got the rig at 88k and to my knowledge, they have never been replaced. So...possibly as old as the rig.

I really appreciate the help guys!

Hey Geoff,

How's my 2nd gen treatin Sarah??

Fink

Silver_Truck

If you've got a few extra bucks what about having em redo the exhaust system from the cross over back? When they do that have em put the first O2 sensor someplace where it will work and also be easy to get to, then the cat then the second the however you want the rest of your catback...4runner is workin good we're heading out with a group of people october 8 to go hit some pretty good trails so that will be its first real test...I'll get some pics your way i keep forgettin...still trying to get the amp situation figured out though

Fink

Yeah I could do that I guess. Does anybody know the magic size for piping on 3rd gens...I think I remember hearing somebody say to leave it stock or I will lose power or something. Is that right?

So I may just have them bend up some new piping and redo it...I'm not real sure, I'll just go there on Monday after class and have them raise it up and look at it and stuff.

Any other suggestions?

Fink

P.S.: Definitely let me know how it does Geoff!!

4-RUNNIN' FREAK

There is always the 8 year emissions warranty on cats from the factory.

Silver_Truck

I think its 2.25"...hopefully midiwall will chime in as he knows his stuff about 3rd gen motors exhausts etc.

masterwacker

the 2nd gen runner and 3rd gen p/u is definitly 2.25". There are some guys on here who have the 2.5 with and w/o the SC and a couple who have 2.25. I know if you have the SC you want the 2.5. Midiwall is definitly the guy you want to answer this question though.

Fink

OK, I just sent Midiwall a PM asking him about the size of the pipe and the placement of the cat. (closer to the muffler or closer to the cross-over)

I think that about covers it.

So once I find out what size pipe to use, I will have them cut everything off at the cross-over, cut off the 02 sensor bungs and cut off the new high flow cat I had put on a week or two ago. And then bend a weld new pipe on, weld on the front 02 sensor (I heards this is not an actual O2 sensor but like an air/fuel ratio or something...I dunno, my service guy said something about it, just wanna make sure it acts the same as an O2 sensor) and then after the front O2 10-12 inches after that weld on the cat., then 10-12 inches after that weld on the rear O2 sensor and then run pipe to the vortex.

That sound good?

Fink

midiwall

Hey man!

Ummm, the stock pipe size on a 3.4L is 2.25". I would stick with that unless you think you're gonna go S/C some point soon.

My cat is a bit "weird" because of the headers and some custom exhaust work, but... The front O2 sensor is 6" down from the Y pipe (where the output of the headers meet), then a Magnaflow HighFlow cat is 12" down from there, and finally the rear O2 sensor is about 8" down from the output of the cat.

Hope that helps!

Fink

Ok cool. I'll go ahead and get 2.25" piping and just have them move everything down a little bit.

I'll get under there and see what I think is best, Basically I'll just position it to where both O2 sensors are within 12" of the cat., maybe put the rear a little bit closer.

I'll let you know how it turns out tomorrow after I get it done.

Fink

Silver_Truck

Make sure they tuck it up nice and tight

Fink

Alright guys here what I had done. He said that he didn't feel comfortable moving the front sensor because it had some special kind of plug or some crap. He said that he had heard that the sensors on the 4runners were better off further up front because it burns hotter and if its get too far down the line it could throw off my O2 sensors. Is this accurate? All I've had done so far just to get rid of that old stock cat. is he cut it out and placed a new piece of pipe in there. The CEL is still on and I'm a little worried if I leave it the way it is something bad will happen.

Can somebody tell me whether this was a smart move?

Thanks!

Fink

midiwall

Hmmm... okay, lets backtrack.

You said in the first post that you had pulled the code and it was a "bad cat". What was the actual code, or maybe more importantly, what's the code now?

And, you said "the light went off of about 1/2 a tank..." did it go off by itself, or did you reset the ECU?

Past that... The stock location on a 3rd gen 3.4L non-CA for the front O2 sensor is about 10" down from the Y, 10" in front of the cat. The rear O2 is about 6-8" down from the cat.

The front O2 is the one that will make the AF/R change, the rear one is there to make sure that the cat is working. So, depending on the code you threw, what you might be looking at is actually a bad REAR O2 sensor. If the front one starts heading south, then the truck will usually run lean and you'll throw "bank too lean" codes (among others).