Only one o2 Sensor??
- Thread starter Born to be Wild
- Start date
Ron Helmuth
Senior Member
revive a thread
Once again just stunned by all the helpful advice from The Durk.
The older our vehicles get the more likely issues such as the O2 sensors will crop up.
Really helpful all of you, but The Durk is just so knowledgeable on these things it is really a blessing to have this information available.
Just wanted to reiterate that the URD-Underdog Racing Development website has great information specific to the fitments of CA and FED 4Runners. Much fitment variations occur between 2wd and 4wd and automatic versus 5speed manuals-so check the charts carefully, peruse the forums to be sure you are getting the correct one.
I believe for my 99 Fed Emissions 5speed V6 4wd I need the 234-4161 Denso for Front/Upstream, and the 234-4154 for Rear/Downstream, but I will be double checking a few more times before I actually plunk down my cash.
Once again just stunned by all the helpful advice from The Durk.
The older our vehicles get the more likely issues such as the O2 sensors will crop up.
Really helpful all of you, but The Durk is just so knowledgeable on these things it is really a blessing to have this information available.
Just wanted to reiterate that the URD-Underdog Racing Development website has great information specific to the fitments of CA and FED 4Runners. Much fitment variations occur between 2wd and 4wd and automatic versus 5speed manuals-so check the charts carefully, peruse the forums to be sure you are getting the correct one.
I believe for my 99 Fed Emissions 5speed V6 4wd I need the 234-4161 Denso for Front/Upstream, and the 234-4154 for Rear/Downstream, but I will be double checking a few more times before I actually plunk down my cash.
TRDFerguson
New member
Need some clarification
Digging up and old thread because it already contains a lot of the info.
I recently bought a 99 3.4L 4runner with CA emissions tag under the hood with practically no exhaust. All thats really there is the flange that the crossover pipe connects to. My "Front Exhaust Pipe" looks like this diagram with two pipes merging together right at the flange:
So knowing (thinking) that I had a CA truck, I bought some CARB approved cats from RockAuto that are listed for a 1999 4Runner 3.4 w/CA emissions. I received a cat that had the single pipe flange and evenly spaced stud pattern like this diagram:
Whats the deal here? Do I have a real CA truck? It has 2 O2 sensors.
Digging up and old thread because it already contains a lot of the info.
I recently bought a 99 3.4L 4runner with CA emissions tag under the hood with practically no exhaust. All thats really there is the flange that the crossover pipe connects to. My "Front Exhaust Pipe" looks like this diagram with two pipes merging together right at the flange:
non CA vehicles have two regular o2's and one cat like this
So knowing (thinking) that I had a CA truck, I bought some CARB approved cats from RockAuto that are listed for a 1999 4Runner 3.4 w/CA emissions. I received a cat that had the single pipe flange and evenly spaced stud pattern like this diagram:
If so you have a cali car and need a wideband (a/f) infront of the cat and a regular o2 after the second cat.
Whats the deal here? Do I have a real CA truck? It has 2 O2 sensors.
phattyduck
Elite Member
If the outlet of your crossover pipe looks like this:
Then you have a CA truck. The next pipe is a normal round pipe, so it sounds like you got the right parts.
-Charlie
Then you have a CA truck. The next pipe is a normal round pipe, so it sounds like you got the right parts.
-Charlie
TRDFerguson
New member
It does not look like that. It has the asymmetrical stud pattern with two separate pipes. Does this suggest it is not CA emissions? The underhood sticker definitely says CA...
phattyduck
Elite Member
Sounds like a new motor (with fed pipes) was swapped in or something. That would explain why the pipes aren't connected.
I believe the only difference between the two engines is the exhaust and O2/AF sensors, so you have that going for you... You will need a CA crossover pipe to match with the CA cat pipe(s).
-Charlie
TheDurk
Elite Member
Those stickers can be confusing. Look in the top left corner under engine family.
If it says: ....HO2S(2), TWC or similar it's Federal.
If it says: ....A/FS, TWC(2), HO2S, it's a Cali.
Ignore everything else.
Otherwise, it may not be the original hood.
TRDFerguson
New member
Since I know Rock Auto will be absolutely no help with returning the cat, I guess you're right that a crossover pipe is probably the cheaper route. If only I hadn't just gone through all the agony of drilling out and replacing all the broken studs on the crossover pipe I have!!! :redbrick:
phattyduck
Elite Member
Ha. I know the feeling, though it was only 1 stud on mine. That's the only reason I have that picture! :biggrin1:
Though, replacing the crossover pipe is a HUGE pain. Read up on header installs to get an idea.
-Charlie
TRDFerguson
New member
I'm planning on calling a muffler shop to see if they could swap the flanges. And I wouldn't be replacing headers, just getting a CA crossover pipe and swapping it. Also a PITA. Its exhaust parts...its all a PITA.
TRDFerguson
New member
Soooo I think its a federal vehicle after all...
Under Engine Family it says SFI, HO2S(2), TWC
IMG_4227 by ANDREW JEFFERS, on Flickr
TheDurk
Elite Member
Yep. That's a FED.
TWC means a single cat (Three Way Converter) and HO2S(2) means two Heated Oxygen Sensors.
You are not the first to be confused by these labels.
Here is a 2000 Cali for comparison:
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TRDFerguson
New member
I suppose that not being the only one to confuse it somewhat softens the blow... but not so much when now both cats I bought AND the used muffler I picked up with the short inlet pipe are all incorrect.
Thanks for the info Durk. Are there any weird technicalities when replacing cats on a federal emissions truck that's registered in CA? Like having to update to CA hardware?
Thanks for the info Durk. Are there any weird technicalities when replacing cats on a federal emissions truck that's registered in CA? Like having to update to CA hardware?
phattyduck
Elite Member
No issue. Once a vehicle is 2 years old (something like that?) it will be tested to the federal standards at your bi-annual smog check.
-Charlie
TheDurk
Elite Member
This is correct.
TRDFerguson
New member
So since I can't buy a federal emission cat like my truck needs (except for mucho $$ from Toyota), can I cut the brand new CARB legal cat I have and weld it onto the pipe with the correct flange? Would that still be flagged for not matching the engine family? Is a universal cat good enough to smog in CA? I don't know what the hell to do anymore... so many rules.
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airmax233
New member
Reviving this thread! Lol
Can someone answer his question. Will buying any universal rear catalytic from a CA shop work?
TRDFerguson
New member
I can't answer your question directly, but I can say that I was able to smog the 99 I was working on without issue. It was a CARB cat that I had welded into the Fed emissions pipe. Without a way to buy a federal emissions cat in CA, this was the simplest way to get it done. Don't know if you'll have any issue getting a shop to do the swap due to liability... I had a millwright at work do it.
