CEL Code 420 and Replacement Catalytic Converter / Exhaust System help

[Erich_870]

I have a 1999 3.4L 4unner with a reoccurring CEL, code 420. It's been on for 2 years now and I've replaced both O2 sensors and the CEL comes back every time I clear it. The rig is Cali emissions too, with dual catalytic converters.

Thanks to Bruce sharing a new source for reasonably priced replacement cats ( http://stores.ebay.com/Muffler-Express-Distribution ), I’m planning to fix this problem once and for all this spring.

What I’m needing help with is verifying which cat needs to be replaced.

I’ll also be looking at whether the rest of my exhaust system needs replacement too. I’ll post some pics of the current system in the day light tomorrow.

My gas mileage has gone down from 18-19 avg to 14-15 over the same time period so I'm hoping to fix that by replacing the faulty cat and whatever else could be to blame.

Thanks,

Erich

[corax]

it will be one of the cats between the oxygen sensor, NOT the one after the last O2 sensor (no way to monitor that one = can't set a code).

[Erich_870]

it will be one of the cats between the oxygen sensor, NOT the one after the last O2 sensor (no way to monitor that one = can't set a code).


Right, the second cat has no O2 sensor monitoring it... :hillbill:

How can I check if the second cat needs to be replaced too? I'm worried my bad gas mileage is from a clogged cat or something wrong with he muffler.

Erich

[Seanz0rz]

i dont have a twin cat vehicle (thank god)

can you switch the "bad" one to the rear, and the rear to the front?

[corax]

How can I check if the second cat needs to be replaced too? I'm worried my bad gas mileage is from a clogged cat or something wrong with he muffler.

Erich


Take it off and shine a flashlight through it onto a piece of paper - don't bother trying to look through the sub-strait as you'd have to get the angle just right to see through it

[Erich_870]

i dont have a twin cat vehicle (thank god)

can you switch the "bad" one to the rear, and the rear to the front?


They are two different and dissimilar pieces.

Here's the front one (the one that's throwing the code) http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?VISuperSize&item=200340513174

And here's the back one http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?VISuperSize&item=200379790154

Erich

[BruceTS]

I just went ahead and got both cats, since I didn't want to have any issues....since the price was right.

[Erich_870]

I just went ahead and got both cats, since I didn't want to have any issues....since the price was right.


That's kind of what I was thinking. My luck the hardware on the back cat would be to far gone and I'd need a new one any way and then be stuck until it arrived, lol. :confused:

I need to get a pic of the cat back exhaust tomorrow to see if you guys think I need to do the whole thing at once.

Erich

[Crinale]

since your truck is 11 years old now... it probably wouldnt hurt...

i will probably redo my whole exhaust at some point, but i have more pressing issues right now, so ill just wait til i break it off :-P

[YotaFun]

Well
Erich,
looks like I will be joining you in the venture, just not for my 4Runner.
My GTI just threw a P0422 and upon research tells me that it too is time for me to get a new cat (granted the car does have 222k+ so I am sure it is due.)

I will be getting the cat for my aunts mini van soon and installing that in a few weeks, if all goes well and her code goes away I will be ordering one for the GTI

[fenrisx]

I've got a 2000 4Runner with a 3.4L, also with dual cats. It threw the 420 on me earlier this year. I assumed it was the cats, but I'm not sure. Now randomly, two days ago, it went off and hasn't been back on. What's up with that? lol..

I was going to get it fixed in January when I got student money, but now I don't know what to do.

[Erich_870]

Yotafun,

Sounds like you'll be an expert by the time I get to replacing mine, lol. I think it's going to be an extremely common problem in the next couple years with all the Cali emission rigs out there.

Erich

[YotaFun]

Erich,
can you ge a pick of your exhaust system?
I have a non-Cali runner and I want to see how the did the second cat on those things.
If (I mean when) I move to Cali I have to see what I have to do to put it into Cali spec...

Avy

[Erich_870]

Avy,

I'll try to today. It doesn't get light here till pretty late so I have to do it at work and we just got some more snow, lol. I'll have to find some cardboard or something to lay on.

Erich

[Erich_870]

Avy,

Here's the pics.

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040242.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040246.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040232.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040233.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040239.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/PC040234.jpg

Erich

[Erich_870]

So now I need some recommendations on economical replacement cat back exhaust systems! :hillbill:

Something with performance improvements would be cool, but I don't want something too loud, so a plain-Jane system is fine with me.

Erich

[YotaFun]

Oh wow, that's a lot different then the non-Cali spec trucks!
Have to do a little more digging into that.

[Erich_870]

I'm going to order these two Cats with my tax return in the next couple weeks. Any suggestions on a cat back exhaust system? :)

Erich

[Seanz0rz]

my roommate just grabbed one off of ebay for his N/A Z32 300zx. it required some slight modifications to fit (advertised for a twin turbo, not the N/A) the problem was how it bolted up to the stock twin pipes, so you shouldnt worry too much about that problem.

i wouldnt spend very much on one, looks like you have alot of rust, so i imagine the elements attack heavily up in AK. this one was stainless and pretty good quality for 130 bucks, i would certainly buy one if i needed one. stock junk is holding out pretty good for me.

[Erich_870]

Just ordered the two cats from Muffler Express. So far I'm impressed with them. I made a note on the order saying that I wanted them to ship them together to save money and they did, refunding me $18! :thumbup: The purchase was delayed a 3 weeks by the hijacking of my paypal account, but that's all taken care of now :roll:

I'll post some pics when they get here :clap:

Erich

[Okie81]

I've seen a lot of people dump their 2 cat setups for a single cat with an O2 simulator

[slosurfer]

just wanted to say "f u" to all you non cali people who have to deal with our even crappier cat laws. My buddy had to spend almost $500 to get his cat replaced on his 89 toy truck because of our stupid laws. :flipoff:

[Erich_870]

just wanted to say "f u" to all you non cali people who have to deal with our even crappier cat laws. My buddy had to spend almost $500 to get his cat replaced on his 89 toy truck because of our stupid laws. :flipoff:


Right back at ya buddy! :thumbup:

I was about to purchase the lower dummy O2 sensor, but after Bruce shared muffler express, I figured I'd just replace the stock system.

Erich

[corax]

My buddy had to spend almost $500 to get his cat replaced on his 89 toy truck because of our stupid laws. :flipoff:


Wow, I think your buddy got ripped. Smog ref never gave my $50 JCWhitney cat a second glance when he was doing the inspection for my engine swap.

[Erich_870]

So it's time for me to bring this thread back from the dead. I've been procrastinating on having my cat's replaced but my MIL's timing belt failure has motivated me to get my long list of work done.

I've had the new cats sitting in my garage for almost a year now partly because I was using my rig for work and couldn't spare the down time, but also because the cats came with a notice that said in large letters "STOP, FAILED CATS COME FROM FAILED EMISSION COMPONENTS UP STREAM! DO NOT REPLACE CATS UNTIL YOU'VE REPAIRED THE PROBLEM THAT MADE THE CATS FAIL!!"

What problems should I look for to follow their imperative message?

Erich

[MTL_4runner]

So it's time for me to bring this thread back from the dead. I've been procrastinating on having my cat's replaced but my MIL's timing belt failure has motivated me to get my long list of work done.

I've had the new cats sitting in my garage for almost a year now partly because I was using my rig for work and couldn't spare the down time, but also because the cats came with a notice that said in large letters "STOP, FAILED CATS COME FROM FAILED EMISSION COMPONENTS UP STREAM! DO NOT REPLACE CATS UNTIL YOU'VE REPAIRED THE PROBLEM THAT MADE THE CATS FAIL!!"

What problems should I look for to follow their imperative message?

Erich



I wouldn't worry too much about the warning, the cats typically fail for 2 reasons:
1) Air getting in upstream of the cats (ie damaged gaskets, hole in exhaust)
2) Excess fuel being dumped into the cats (bad O2 sensor, injectors, MAF, etc)

Do your best to look over everything and then go ahead and install them.

[Erich_870]

I wouldn't worry too much about the warning, the cats typically fail for 2 reasons:
1) Air getting in upstream of the cats (ie damaged gaskets, hole in exhaust)
2) Excess fuel being dumped into the cats (bad O2 sensor, injectors, MAF, etc)

Do your best to look over everything and then go ahead and install them.


That's good to hear. I've had both a bad MAF and O2 sensor prior to this so that is my hope.

Erich

[Erich_870]

I had the cats replaced yesterday along with other tune up items (new T-belt, plugs/wires, oil change, and block heater) and the rig drives great now!

I did have a small issue where there was a loud resonance sound that happened at 10 and 20 mph, so I swung back by the shop. One of the O2 sensors was just barely touching a heat shield on the cat so they tweaked it a little and now it’s fine.

Here are some pics:

I couldn’t see down the inlet side, but here’s what the catalytic core looks like stock. My replacement cats have a square pattern with slightly larger holes. I can hear a difference in the engine sound now, it sounds more “throaty” :clap:

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/CatyliticConverter.jpg

http://i7.photobucket.com/albums/y261/Erich_870/Toyota%204Runner/2011-03-31115330.jpg

Erich

[20005spd]

the front cat is steel and looks like its wound in a circle. the rear cat is the one doing most of the work, with the expensive metals, and honeycomb shape. i replaced both of mine recently with a single universal cat and yes the sound is fun and no check engine light since :thumbup:

[Erich_870]

the front cat is steel and looks like its wound in a circle. the rear cat is the one doing most of the work, with the expensive metals, and honeycomb shape. i replaced both of mine recently with a single universal cat and yes the sound is fun and no check engine light since :thumbup:


Interesting. I assumed both cats had precious metal in them. What does the front cat do then, just get hot and help burn off remaining fuel/C0?

I'll have to snap a pic of the second cat to look for differences in the core shape.

Erich

[YotaFun]

I don't know about the rear cat doing most of the work.
Usually when we get a 4Runner in with the P0420 code, we replace the front cat.

Brian, you did the universal on the 2000?

[MTL_4runner]

the front cat is steel and looks like its wound in a circle. the rear cat is the one doing most of the work, with the expensive metals, and honeycomb shape. i replaced both of mine recently with a single universal cat and yes the sound is fun and no check engine light since :thumbup:


I'd be very surprised if this was the case since the second O2 sensor should be there to verify the front converter is working properly. The second cat is really there to clean up anything the first converter missed....thus it results in lower emissions (which is why California vehicles had this setup first).

[20005spd]

my truck had factory. an air/fuel sensor, then 2 cats in a row, then an 02 sensor. at least around NE you can put whatever cat makes that rear 02 sensor happy and all is good. we dont do tailpipe tests on anything 96+. OBD2 will find an emissions problem and cause the readiness monitors to read incomplete which is sent to the inspection machine via OBD2 connector dictating whether or not you get a sticker.

[YotaFun]

Jamie's right on this one Brian, at least out of all the Runners that have been coming in oo+ i have seen that way, can you get a pic if you still have it?

[MTL_4runner]

Brian, you are right on the configuration, but not on the operation. The converter closest to the engine gets the hottest and by default does the most work to "clean" the tailpipe emissions. The second O2 sensor is at the end of both converters but again it really is checking the front converter since that one is far more likely to wear out than the one further downstream.