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2004 4.7 Cat Questions (CA Emmissions)

974 views 25 replies 8 participants last post by  timatoe 
#1 ·
The other day I got a CEL with a P0420. I am looking at replacing the Y pipe with both cats. Did the Y pipe change from 2003 to 2004?

I found a couple OEM replacements on one of our favorite online retailers and they say *to 05/02/03.* Did they really change the design in May of 2003?

Also, many of the options state not legal for sale or use in CA... Does this just mean they arent CARB approved? Or does this mean they wont work on a vehicle with CA emissions? They still have two cats with 4 O2 bungs so I dont see why they wouldnt work.

I appreciate any help!
 
#3 ·
Thanks, I don?t live in CA. I live in MD. We have bi-annual emissions testing but no visual inspection of the cat. They just plug into the OBD port and take a reading. Usually in and out in 2 minutes. I?m less concerned about not having a CARB approval than I am about fit and getting rid of the code.

I have the later style with two cats on the Y pipe and no main cat after the Y pipe. I?ve just seen conflicting info saying the design changed after build date 05/02/03 but I also read the change happened in late model year 2004. So I just want to make sure I order the correct one.

Thanks again!
 
#7 ·
Thanks, appreciate it.

SLOW down are you sure the cats bad -?
We have some work before condemning them...

And the cats do not need to be CARB approved in MD.
Thanks. I didn?t think I would need 50 state cats. See description below as to why I think it?s the cat. But I will not order a new Y pipe until we are sure. Appreciate the caution!

The Y pipe design did change around 2003. Since you have a bank 1 and 2 is the 420 for bank 1?

You could start by replacing the after cat O2 sensor on bank 1 or both banks if your sensors are old. Also look for exhaust leaks.

I punted on my 97 4Runner and put a bottle of Cataclean in and the code cleared in 120 miles and had stayed away for 4000 miles. But the 4Runner had sat for over a year with a bad engine before I bought it and swapped engines.
I replaced the drivers side upstream in May as it went bad and the code on the scanner pointed to the 1/1 sensor. It started running terrible and smelled awful! A new mopar sensor did the trick then.

I know the manifolds aren?t leaking and I would be shocked if I had a leak from the manifolds to the y pipe. The motor was rebuilt in March so the manifolds were decked and new gaskets were installed along with new bolts at the Y pipe.

I took the jeep wheeling last month and unfortunately got into a lot of mud (not by choice). Afterwards I did have some gurgling sound from the exhaust. My guess is water got in the tail pipe maybe towards the muffler. I?d be surprised it water got all the way up to the cats.

Right now the jeep smells like it?s running rich. From what I read, I sort of ruled out O2 sensors because I thought that unless there was a leak, the P0420 code will be present when both sensors are getting similar readings, indicating the cat isn?t working any longer. The cats have about 130k on them. I?m all about not spending the money on a new Y pipe but what I don?t want to do is replace the remaining 3 O2 sensors to find out it?s the drivers cat anyways.
 
#6 ·
The Y pipe design did change around 2003. Since you have a bank 1 and 2 is the 420 for bank 1?

You could start by replacing the after cat O2 sensor on bank 1 or both banks if your sensors are old. Also look for exhaust leaks.

I punted on my 97 4Runner and put a bottle of Cataclean in and the code cleared in 120 miles and had stayed away for 4000 miles. But the 4Runner had sat for over a year with a bad engine before I bought it and swapped engines.
 
#8 ·
I agree with idea replace post cat sensor* -

The fact you changed o2 sensor would have me look at the readings - as there is no code that says change them.

As I have the luxury of shop equipment - Ideally I would use the scanner and graph the pre and post cat sensors for review. That and I hate to spend,

*http://www.bigdaddiesgarage.com/str...MIxpLw94_G1wIVm4qzCh1LPQHvEAQYBCABEgKJhPD_BwE

Thats not an endorsement - call it a diagnostic aid
 
#10 ·
I mentioned the comparison being needed pre and post cat sensor readings.
You have had an issue with S1 already I would like to see what that was.

example if your running rich now it will affect new cat eventually.

Does your scanner show live data?
 
#11 ·
I mentioned the comparison being needed pre and post cat sensor readings.
You have had an issue with S1 already I would like to see what that was.

example if your running rich now it will affect new cat eventually.

Does your scanner show live data?
Understood. It?s not my scanner. It?s a friend of mine. I asked him if it will data log the o2?s. I will see what he says.

My assumption was it was a bad cat was causing it to run rich.
 
#12 ·
lets just look at sensor voltages -

To expensive to not do checking first.. . UNLESS you want to gamble on a post cat o2 sensor, less than a 50 50 chance.
 
#14 ·
judunty84 said:
Ok thanks, I am going to try and get over there tomorrow to scan it. Thanks again!
if you have a android anything get Torque Pro and a dongle. It will do the graphing.

But if you have anywhere near 200k miles on the factory O2 sensors it's time to get new mopar or NTK sensors and start over

Also, no exhaust leaks within 4ft of a O2 sensor. (Or no exhaust leaks.) The reversion will draw fresh air in and totally screw up the O2 sensor reading.

With live data what are your LTFTs for bank 1 and 2?
 
#15 ·
Save a lot of money

Do the spark plug anti fouler trick.

The po of mine obv had a bad cat and instead of replacing the whole y he had an aftermarket welded in.

It would still throw a 0420 code.

Spaced out the rear o2 with the antifouler and boom she passed pa emissions for 3 years until I found the y pipe locally from a member of this board and swapped it out.
 
#16 ·
Does you Grand have and exhaust leak at the left manifold? It it does it will cause the o2 sensors not to read write and cause a p0420. Seen a few of these especially on the WK's . Being you not in California then CARB excempt doesn't apply to you. And the o2 sensor exstensions/ coolers do work if you have a weak cat.
 
#19 ·
JMZ101586 said:
Save a lot of money Do the spark plug anti fouler trick. The po of mine obv had a bad cat and instead of replacing the whole y he had an aftermarket welded in. It would still throw a 0420 code. Spaced out the rear o2 with the antifouler and boom she passed pa emissions for 3 years until I found the y pipe locally from a member of this board and swapped it out.
was that me?
 
#20 ·
I forgot to mention the sensor voltages I posted earlier were at idle.

I figured out how to log LTFT?s and sensor voltages and drove around to make two logs. There are nearly 400 frames of data. I?m trying to figure out how to get it out of the scanner to a computer.

Here?s the weird thing. While I was logging, the motor hesitated twice and then the CEL turned off. No codes are stored on the PCM anymore. WTF!
 
#26 ·
I just replaced a cat. They seem to either be CARB compliant and typically 50 state compliant or 49 state compliant minus CA or 48 compliant minus CA and NY.

CARB is 100% a CA thing, it actually means California Air Resources Board, which is short for we found another way to take your money. I wouldn't worry at all about it if you don't live in CA.
 
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