Fed 4runner in California

[ASilhouetteLie]

Hey everyone,
So got a 96 federal emissions 4runner that just barely failed California smog. Been searching and searching for a few days now and didn't find complete information for my case. Not really sure what I should/could do.

Here's the results before tuneup (seafoam through intake, plugs, wires, front o2 sensor, cleaned MAF and throttle body)

Now after...

Hope you can read it. My phone camera sucks...

So I'm not too far off. Any other tips, suggestions? New cat? If so 49 state or 50? I definitely don't want a P0420 or anything so OEM at $1500? Aftermarket? Magnaflow or Eastern?

Could really use some insight.

Thanks!

1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

 

[truedef]

Hmm, I wont be of any help I just wanted to say thanks for sharing.

Its interesting to obtain such data where someone has a before and after Emission reading with a tune up in between. Gives some real proof that you cleaned something up.

Have you pulled out the o2 sensors and gave them a look?

 

[StreetCreeper]

Hey everyone,
So got a 96 federal emissions 4runner that just barely failed California smog. Been searching and searching for a few days now and didn't find complete information for my case. Not really sure what I should/could do.

Here's the results before tuneup (seafoam through intake, plugs, wires, front o2 sensor, cleaned MAF and throttle body)


Now after...


Hope you can read it. My phone camera sucks...

So I'm not too far off. Any other tips, suggestions? New cat? If so 49 state or 50? I definitely don't want a P0420 or anything so OEM at $1500? Aftermarket? Magnaflow or Eastern?

Could really use some insight.

Thanks!

1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

Read this http://www.toyota-4runner.org/3rd-g...-journey-into-smoggy-abyss-how-lower-nox.html

 

[ASilhouetteLie]

Hmm, I wont be of any help I just wanted to say thanks for sharing.

Its interesting to obtain such data where someone has a before and after Emission reading with a tune up in between. Gives some real proof that you cleaned something up.

Have you pulled out the o2 sensors and gave them a look?

Yea I've read through tons and tons of very helpful info so definitely happy to give back... I actually swapped out the front (before cat) O2 sensor with one from the dealership. Didn't do the rear one as I read it doesn't directly affect smog but rather meters your CC.

StreetCreeper,
Very good read. I'd really at all cost not wanna deal with buying a new cat but do you think since I failed the HC portion it would go higher and cause me to fail anyway?


1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

 

[StreetCreeper]

StreetCreeper,
Very good read. I'd really at all cost not wanna deal with buying a new cat but do you think since I failed the HC portion it would go higher and cause me to fail anyway?


1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

First, I'm no expert on this stuff so take everything I say with a grain of salt. But looking at your numbers and knowing what you've already done, I think your best bet is to get a new cat. Even if you pull out all the stops like I did, I don't think you will bring your NOx down by 112 ppm. I was only able to bring mine down by 87 ppm, but that lower NOx level increased my HC by 10ppm.

If you were to achieve a similar drop in NOx levels, one might assume your HC is going to increase by at least 10 ppm as mine did, which is problematic for you since as you know, you are already maxed out at 25 mph @ 34 ppm and even over on the 15mph test @ 57.

A new California legal Walker cat would be what I would be looking to buy. I think you can get those cats for under $200 and probably get it installed for another $100 or less.

 

[ASilhouetteLie]

First, I'm no expert on this stuff so take everything I say with a grain of salt. But looking at your numbers and knowing what you've already done, I think your best bet is to get a new cat. Even if you pull out all the stops like I did, I don't think you will bring your NOx down by 112 ppm. I was only able to bring mine down by 87 ppm, but that lower NOx level increased my HC by 10ppm.

If you were to achieve a similar drop in NOx levels, one might assume your HC is going to increase by at least 10 ppm as mine did, which is problematic for you since as you know, you are already maxed out at 25 mph @ 34 ppm and even over on the 15mph test @ 57.

A new California legal Walker cat would be what I would be looking to buy. I think you can get those cats for under $200 and probably get it installed for another $100 or less.

I really appreciate it! I'll look into the Walker cats. Are they one of the better ones out there? I read a few stories about ppl having horrible experiences with magnaflow so I was trying to steer away from them.

It's running so much better since the tune up that I thought it would pass for sure. Oregon is looking more and more appealing lol.

 

[yota_addict]

Taken from an article on the net - "High NOx is from combustion chamber temps in excess of 2500 degF. High HC indicates a rich running condition ( or a false lean) and high o2 indicates a lean ( or false rich) running condition. Some possible causes of high HC: engine not reaching operating temp, running rich, ignition misfire, mixture misfire, or compression fault misfire, leaky injector. Some possible causes of high NOx: inoperative EGR, engine running too hot, excessively lean mixture, excessive carbon build up in the combustion chamber, over advanced ignition timing, incorrect valve timing, ect."

Are you running rich? Is your timing proper? Definitely change your cat with oe cat. They passed mine but the guy said he shouldn't because cat was not oe or proper for visual inspection. Works fine and passed test.

 

[ASilhouetteLie]

Taken from an article on the net - "High NOx is from combustion chamber temps in excess of 2500 degF. High HC indicates a rich running condition ( or a false lean) and high o2 indicates a lean ( or false rich) running condition. Some possible causes of high HC: engine not reaching operating temp, running rich, ignition misfire, mixture misfire, or compression fault misfire, leaky injector. Some possible causes of high NOx: inoperative EGR, engine running too hot, excessively lean mixture, excessive carbon build up in the combustion chamber, over advanced ignition timing, incorrect valve timing, ect."

Are you running rich? Is your timing proper? Definitely change your cat with oe cat. They passed mine but the guy said he shouldn't because cat was not oe or proper for visual inspection. Works fine and passed test.

I'm pretty sure it was running lean and had a slight misfire before I changed out the plugs o2 sensor etc. I thought the timing was set on the truck already and couldn't be adjusted? I'm maybe even thinking the PO ran the truck for miles and miles with the misfire causing the cat to go bad.

Probably gonna go with the Walker direct fit cat as soon as they email me back about federal emissions and running a CARB certified cat together.

1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

 

[TheDurk]

The whole Cali. two-cat exhaust system started with MY 1999. You still need CARB approved parts (and not all of them are) but the FED/CALI spec thing does not exist for you. If you buy a cat, it should be the 49-state type, but CARB approved for use in California. They exist. Manufacturers/retailers will usually not ship non-CARB approved parts to Cali.

 

[ASilhouetteLie]

Hey everyone

So super late update:

Got the truck to pass finally! Here are the newest results...



So since my last post I bought and installed a walker cal-cat. Quality was sort of meh but it's definitely doing it's job. Shortly after installation I started getting a weird hesitation at 3K rpm. Turns out the coil pack boots were shot so replaced them and is running great now.

Still puzzled that I'm on the border for hydrocarbons but I'll take the pass for now and finish all maintenance I have left and see if in two years I get a pass again. That or its off to Oregon lol.

Anyway thanks to everyone who chimed in. I would've been lost without the hours of searching this forum and your help.

Thanks everyone!
Cheers [emoji482] [emoji482] [emoji482]

1986 Toyota Supra
1987 Toyota 4Runner
1996 Toyota 4Runner

 

[IBallEngineer]

Good for you that you passed.

Just a note, we tend to over complicate things as humans.

HC is Hydrocarbons, or basically fuel that did not burn in the combustion process. We can call it any number of things, and point to many things, but in the end it all boils down to incomplete combustion(burn). Slightly leaky valve, bad injector, low compression, intake leak, you name it. I'm sure someone will correct me saying there is some scientific reason it isn't unburnt fuel, but no matter, get the combustion right and the HC is good. CO is a better measurement of rich/lean conditions.

Glad you made it go!