Failed CA smog twice

[5VZ-FE]

I've failed CA smog twice in the last two weeks. First one was high HC and NO, both at 15 mph, while 25 mph was fine. I replaced spark plugs because they were old, threw on a new air filter and ran it at freeway speeds for 45 min right before the test. Failed again, slightly better numbers.

The smog tech this time said to seafoam it, then put new o2 sensors in, then retest and if it still doesn't pass replace the cat(s). I'm going ahead with the o2 sensors but the cat replacement doesn't make sense to me. I've been reading thread after thread of people throwing a P0420 on trails, in traffic, etc. and I've never once seen that code thrown on mine. It seems like if I actually had a cat issue I would also be getting the code frequently. Is there something else that I should be considering? The price to replace just one of the cats is ridiculous and I'm going overseas for 4 months so I'm thinking if this doesn't work I might just PNO it and figure it out when I get back.

Worst part was the tech said I would've passed with these numbers 5 months ago...:smashputer:


Edit: I just found <a href="!251593!3rd-gen-t4rs/251593-o2-sensor.html">this thread</a> and now I'm not sure I am CA emissions. I have the same sticker and what looks like 1 catalytic converter and 1 muffler. 4Runner was originally sold in Arizona. Why would it say conforms to California regulations if it isn't?

 

[Pyral]

I've failed CA smog twice in the last two weeks. First one was high HC and NO, both at 15 mph, while 25 mph was fine. I replaced spark plugs because they were old, threw on a new air filter and ran it at freeway speeds for 45 min right before the test. Failed again, slightly better numbers.

The smog tech this time said to seafoam it, then put new o2 sensors in, then retest and if it still doesn't pass replace the cat(s). I'm going ahead with the o2 sensors but the cat replacement doesn't make sense to me. I've been reading thread after thread of people throwing a P0420 on trails, in traffic, etc. and I've never once seen that code thrown on mine. It seems like if I actually had a cat issue I would also be getting the code frequently. Is there something else that I should be considering? The price to replace just one of the cats is ridiculous and I'm going overseas for 4 months so I'm thinking if this doesn't work I might just PNO it and figure it out when I get back.

Worst part was the tech said I would've passed with these numbers 5 months ago...:smashputer:


Edit: I just found <a href="!251593!3rd-gen-t4rs/251593-o2-sensor.html">this thread</a> and now I'm not sure I am CA emissions. I have the same sticker and what looks like 1 catalytic converter and 1 muffler. 4Runner was originally sold in Arizona. Why would it say conforms to California regulations if it isn't?

It will say on the sticker under the hood if it's a CA smog vehicle or not. You can register non-CA smog vehicles in California after a certain age as long as they still have the original equipment. If the original smog equipment fails or was already replaced they'll force you to install CARB certified stuff before you can register it.

Mine is steadily approaching this same point reading my Smog results seeing the HC levels go up. I don't know if it's the cat wearing out before it clogs up which is usually when you see P0420.

One trick I've heard of is adding bottles of HEET (used to deice fuel) to the gas before taking the test, it is basically alcohol and I guess it burns cleaner and makes the car squeak by if it was barely failing before.

Clean the MAF too.

 

[Endlessblockades]

Sounds like your 99 is Federal, so you have only 1 cat, right? Unless the PO swapped a (scooped?) hood what does the emissions sticker say? Have you checked your emissions data readiness with a cheap scanner prior to test?

Edit - oops, our replies crossed.

 

[5VZ-FE]

What does the emissions sticker say?... Have you checked your emissions data readiness with a cheap scanner prior to test?

Emissions sticker says "...conforms to EPA NLEV regulations... and to California regulations applicable to 1999..."

Here is a folder with photo of the sticker and two of the cat.

I did use my scanner to check emissions readiness and it said all was good. It also said vehicle is certified to California ARB OBDII requirements and said O2 sensor voltage was in range.

Is it possible I have a CA emissions vehicle that someone removed 1 cat from? I suppose...

Based on this post,

That's a federal. No doubt. The verbiage is confusing--ignore it. The line that counts is: SFI, HO2S(2), TWC.

if it were a Cali, it would say: SFI, A/FS, TWC(2), HO2S or similar. Years vary slightly.

HO2S is heated oxyen sensor, TWC is three way converter, A/FS is air/fuel sensor.

So yours has two standard O2 sensors and a single cat, i.e Federal system.

I am going to order O2 sensors for a federal system. Those stickers are super confusing.

 

[Hungryhawk]

Do you have an OBD2 serial plug under dash?
The OBD2 records data from your sensors and various driving conditions. The distance driven and accumulated data is part of the smog test.
My understanding is miles driven with good passing data is recorded under city , highway & idle conditions.
Seems you are getting helpful feedback from your test shop. Sorry it is going so slow for you.
I usually pay my renewal fees timely then complete the smog portion many weeks later as needed. I once had a fuel tank evap control system vacuum leak test fail. I wound up taking apart the metal to rubber fuel fill line below the gas door and greasing an O-ring. It worked.

 

[phattyduck]

California only got 2 cats and the AFR sensor for '99+ model years. '96-'98 all had 'Federal' emissions and all '01/'02 had the AFR+dual cats.

So, your 4Runner already meets "CA emissions" for the year of the vehicle (assuming you have a 1998, like listed in your signature).

-Charlie

 

[5VZ-FE]

So, your 4Runner already meets "CA emissions" for the year of the vehicle (assuming you have a 1998, like listed in your signature).

No, it's a '99. The '98 was a T100. Based on TheDurk's post above I am confident that I have a Federal Emissions 4Runner and the issue is simply convoluted wording on the sticker.

Now I'm just wondering if there are any steps I can take other than 02 sensors before replacing the cat. I think I'll try the seafoam and heet/acetone suggestions before the next test too.

 

[phattyduck]

Whoops, I saw the '98 on the T100 and skimmed over the '99 for the 4Runner.

New O2 sensors is definitely something you will want to do before the cat. You'l want new sensors in there for the health of the (possible) new cat anyway.

A few applications of a LOT of acetone does seem to have helped my CA emissions '99. Like 5% of the tank a few times. I also have new Denso front and rear sensors. In the end, I put in a short spacer for my rear O2 to make the ECU happy and it blows well enough for the tailpipe portion of the test (not great, but easily passing).

Some also say that having a bit of acetone in the tank for the test itself helps - not sure if that is true.

-Charlie

 

[5VZ-FE]

In the end, I put in a short spacer for my rear O2 to make the ECU happy and it blows well enough for the tailpipe portion of the test (not great, but easily passing).

Huh that's interesting. What does the spacer do to make the ecu happier?

 

[Twisted Sid]

The spacer pulls the o2 sensor out of the direct path of the exhaust gasses so it tricks the computer into thinking its running a bit cleaner and doesnt throw a code. I have had one in my 99 for about 6 years to help with a p0420

 

[5VZ-FE]

Ah ok. I don't think that'll be much help for me because I've never had the P0420 code, my issue is just with the tailpipe sniffer. Cool workaround though.

 

[Pyral]

The spacer pulls the o2 sensor out of the direct path of the exhaust gasses so it tricks the computer into thinking its running a bit cleaner and doesnt throw a code. I have had one in my 99 for about 6 years to help with a p0420

That's an insta-fail in a CA smog test, spacers are illegal and are considered a cheat device. I wouldn't recommend using it if you need to pass CA smog.

If you're getting by in CA with one, your smog shop is being very nice because they shouldn't pass you. Outside of a smog state, the spacer is an option (on cars older than ~15 years)

Also they only work because 3rd gens are sort of dumb, new cars will test against these by intentionally running rich briefly and looking for a rise from the O2 sensor, if they see none because a spacer was used, you'll get a CEL.

 

[phattyduck]

That's an insta-fail in a CA smog test, spacers are illegal and are considered a cheat device. I wouldn't recommend using it if you need to pass CA smog.

I probably should have made that more clear. The CA rear O2 sensor sits right above the trans crossmember and is a bit hard to see, but it is always a risk. Also, easy to remove for inspection...

I do it because the CEL in day-to-day driving - the tailpipe emissions are still in spec.

-Charlie

 

[Twisted Sid]

That's an insta-fail in a CA smog test, spacers are illegal and are considered a cheat device. I wouldn't recommend using it if you need to pass CA smog.

If you're getting by in CA with one, your smog shop is being very nice because they shouldn't pass you. Outside of a smog state, the spacer is an option (on cars older than ~15 years)

Also they only work because 3rd gens are sort of dumb, new cars will test against these by intentionally running rich briefly and looking for a rise from the O2 sensor, if they see none because a spacer was used, you'll get a CEL.

And that's why it pays to have a good working relationship with people. Been going to the same shop for many years.
Had one in a 2014 nissan too and it passed what ever test you're talking about

 

[5VZ-FE]

It ended up being a really dirty MAF.