Catalytic Converter Replacement
 

Well, I ordered a replacement catalytic converter the other day and it arrived today. It was my impression after looking under the truck (obviously not close enough) and after talking with the dealer that my truck had only one cat since I'm not in California. Well, the part arrives today. All looks ok until I notice the flange after the cat for the oxygen sensor. Well....my stock unit does not have that. It has a threaded plug that the sensor screws into. There's problem one.

The second problem is that after a closer inspection, it looks like I do indeed have dual cats. Guess that's why they prompted me about front or rear when I ordered, but I thought they were thinking I had a California emissions truck. Long and the short of the matter, I do not know which of the two cats is throwing out the "Catalyst Efficiency Below Threshold" code and causing the check engine light to come on. Add to that the fact that this so called "direct fit bolt on" Eastern catalytic converter doesn't look like it would work anyway because of the opening for the oxygen sensor. Here's a few pictures...

Pic #1 is what I think is the front cat
Pic #2 is what they are calling the rear cat
Pic #3 is the replacement Eastern rear unit, particularly the flange for the O2 sensor

http://pics.montypics.com/phi1514/20...ctures_002.jpg

http://pics.montypics.com/phi1514/20...ctures_005.jpg

http://pics.montypics.com/phi1514/20...ctures_006.jpg

What's your advice guys? The simplest thing to do would be to cut out the rear cat and have a new one welded in at the exhaust shop in the morning, assuming he has one but I don't know if it's the front or rear cat throwing the code to the computer. Plus, I doubt he has one in stock that's not high flow. I've got to have my muffler and exhaust tip replaced so that's why I'm going to be there tomorrow and I was hoping to get all of this done at one time.

Is there any way to isolate the problem to which cat is throwing the code? I'm already going to be out about $35 for the expedited shipping of this cat unit because I wanted it here by today so it could be put on tomorrow. Now, I've got to pay to mail it back to them. After looking at their website closer, they do offer a front and rear cat unit but again I assumed this was just for California emission standard trucks. I'm at a loss here guys...help!!!

Matt

BTW...the code that was thrown out was for Bank 1. How in the world would the ECU know to differentiate the front one from the rear one since there is no sensor between the two cats? I'm assuming Bank 1 would be the first cat and Bank 2 would be the second one.

Matt

I find it extremely strange that you have a bad cat. I mean, what caused the bad cat? What if it happens again?

A truly clogged cat can be caused by a number of things. Bank 1 is the front (closest to the engine).

What was the exact code? Have you posted it here on YT (or are you positive)?

Just trying to get to the root cause so it doesn't bite you again. :bigok:

I guy at work had a handheld OBD2 that he hooked up to my truck. It scans all of the vehicles systems for problems and as each one checks out, the light for that particular system goes out. All went out except for the one related to the cat system. Here's the info I got from it...

Catalyst Monitor check wouldn't clear (all others did)

P0420--Catalyst System Efficiency Below Threshold (Bank 1)

Matt

I find it hard to believe that my cat went out also, even though I've got 150k+ miles. The only thing that would lead me to believe that it could be bad (other than the codes) is that I've read and/or heard that idling the truck for long periods of time can damage one or both of the cats. I've done that on several occasions at football games while tailgating. If my inverter started alarming low voltage, I would usually crank the truck up and let it idle for at least an hour, if not longer. Could that have damaged it?

Matt

I doubt extended idling of that nature would cause a bad cat. I would PM Jamie (MTL_4Runner) and direct him to this thread. He is pretty good with net diagnosis, especially related to engine codes and where to go from there.

https://www.yotatech.com/forums/members/2548.html

The one thing that I don't understand is that it is so sporadic. The CEL may pop on and stay on (putting out the catalyst code) for a few days or a week and then just a quickly as it came on, it will go out by itself. Before this recent bout with it, it was months since it last came on. I don't get that at all. If the cat was bad, wouldn't it come back as soon as it was cleared?

Matt

Also, is there any way to tell if it is clogged, or just not operating as efficiently as it should? If it's not clogged, then I think I'll just clear the code when it pops up and see what happens. I just don't want to lose any performance or fuel mileage because of this thing.

Matt

I was going to suggest that you have it checked out by an exhaust dude, because when I did my muffler, my guy told me (@ 120k) that my cat is comin' a little loose inside.

After some research, I found out that cats don't just go "bad" that easy, it's more of a getting clogged thing which would kind of support your sporadic CEL behavior.

Matt -

See the article I quoted above. That is really the only way that I know of. As you can see, it's pretty involved and would probably be easier (and cheaper) just to get a new Carsound cat or similar and go from there if the new cat does not work.

FYI...

I threw a CEL for a bad cat on my '00 a ways back at about 70k miles. The dealer replaced the cat under the emissions warranty, no charge.

Well, I wish they would replace mine under warranty but I am way outside of that since I've got 155k+ miles.

I got my muffler and tip replaced this morning. The exhaust sound and flow is as good as the first day I bought it. It's great!

I talked to the mechanic at the plant I used to work at who is painting my roof rails for me. I mentioned to him about the exhaust leaks at the inlet pipe to the muffler and asked him if there was a possibility that there was enough air in leakage through these openings to trick the rear O2 sensor into thinking that the cats were bad. It was just recently that I noticed the change in my exhaust tone, but there could have been small leaks at the muffler inlet for some time and started causing the CEL light to come on. I guess just driving it with these leaks and not knowing, they eventually opened on up. He thought this could be possible since that O2 sensor is really not that far from the muffler inlet, even though the muffler is downstream.

I went to Walmart and got an OBDII code reader after I had the muffler and tip put on and cleared the codes out of the ECU. I'm just gonna see what happens from here on out. It will probably be something I just live with for a while if indeed the CEL does come back on and throw that same code. BTW...here's a pic of the cat system that I took while the truck was on the rack. It's dual cats alright and after talking with the exhaust shop owner and the service manager at Limbaugh Toyota this morning, there is no way to tell which of the two could be bad if indeed they are. Plus, there was a poster in the exhaust shop talking about cats and all of the other things that could cause them to fail or throw a code to the computer so I'm not doing anything with this for a while until I can gather a little more data, but thanks for ya'lls help.

http://pics.montypics.com/phi1514/20...ctures_008.jpg

Here's the poster I was referring to above...

http://pics.montypics.com/phi1514/20...ctures_009.jpg

http://pics.montypics.com/phi1514/20...ctures_016.jpg

http://pics.montypics.com/phi1514/20...ctures_014.jpg

We'll see what happens from here on out. Thanks again guys.

Matt

He is right. Cats do not just go bad. 99% of the cats that are bad, are caused because of some other aspect of the engine causing it. You can check to see if the cat is bad in a few different ways.. you can knock on it and listen for rattling, Pull it off lok through both ends and see if it shows signs of melting or the brick breaking up. But chances are if your cat is bed, there is a high possibility that something caused it to go bad... without fixing that problem it could cause premature life on the next cat you install.

I wish I could help out more with the problem but my Magnaflow catalog does not list a direct fit converter for the 01 model. My catco book does list a direct-fit converter to replace your front cat and it does look like the one you have is pic 1. with the 02 sensor flange and all.

I do not think that is possible. It would sound somewhat believeble if the air was entering beforecat(s) or 02 sensor(s) for that matter but even then... I am not too sure about it. People have exhaust leaks at their manifolds all the time and it does not throw a cel... much less a leak by the muffler.

Matt, You are having EXACTLY the same problem I and others are having with this P-0420 code. As most of us know there few people out there more knowledgeable about 4Runner's than Gadget. I was fortunate to have him respond to this issue at the end of this thread (read the last three posts) : https://www.yotatech.com/forums/show...882#post841882

Check out this info about our Cats, this code, and what we can do to address it (I havent taken these steps yet, but will be soon). It sounds like the approach to take is to get the oxygen capture test done, then either replace the cats (if they are bad) or get the URD sim installed (if they are good) to keep that light off.

4Runner4Christ,
Are you willing to bite the bullet and have your rear cat cut out and one of these MagnaFlow high flow cats welded in? I don't know if I am. Besides the fact that the chance is there that it will not fix the problem (if the problem was in the front cat all along) are you concerned about the added sound from your exhaust due to the installation of a high flow cat as opposed to a regular one?

As far as the entire cat assemblies go (Eastern, DEC, etc), if what Gadget says about aftermarket cats is true, then I don't want to touch them. That's the last thing I want to do is spend $500+ for a front and rear aftermarket cat and a few months later be right back where I started. I will say this. I'm sending back this Eastern unit that I ordered this week because the port for the rear O2 sensor isn't correct. Looking at it compared to the stock assembly under the truck....there's a world of difference. The stock assembly appears to be much better built than this Eastern unit which probably explains why it costs about 1/4 of what a stock unit would. What's the deal with this oxygen capture test?

Matt

Matt,

I really havent researched any cat replacement solutions such as the Magnaflow high flows, so I'm not sure about doing any cutting yet. My course of action will be:

1. Get an oxygen capture test done to determine if my cats are good or trashed.

2. If they are good, I will be getting one of Gadgets URD sims to fix this inaccurate CEL/P-0420 issue.

3. If they are bad I will research some cat replacement options (the last possible option will be to fork over $1400 to the dealer to swap everything out).

Brad

What is the oxygen capture test and how do you do it?

Matt

I bought one of these little jokers at Walmart today....

http://www.iequus.com/products.php?category_id=1_10_7

I got the 3030 model. Didn't really see the need for the other functions of the more expensive models. I cleared the code before I left Walmart and have driven quite a bit since this morning and so far, no re-occurence of the CEL, but I'm quite sure it will pop back up sooner or later. Until I can do some more research, I'm just going to clear the code everytime it pops up.

Matt