Failed smog test

[mkzg]

Hey so I have a 1998 3.4l 4runner I just tried to smog and it failed for HC and NOx being high.

The tech said I have a weak cat, I’ve read I could do seafoam and it probably would fix the issue, but not sure. What does anyone here think? Injector cleaner and seafoam? For sure a cat? O2 sensor?

No engine codes at all



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[ElectroBoy]

Hey so I have a 1998 3.4l 4runner I just tried to smog and it failed for HC and NOx being high.

The tech said I have a weak cat, I’ve read I could do seafoam and it probably would fix the issue, but not sure. What does anyone here think? Injector cleaner and seafoam? For sure a cat? O2 sensor?

No engine codes at all
View attachment 348252


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I used to get cat problems right around smog time with my 2000. I used a bottle of Cataclean and that seemed to do the trick. YMMV.

https://www.amazon.com/Cataclean-12..._1_3?keywords=cataclean&qid=1573618468&sr=8-3

 

[4Reak Show]

Cats are expensive. And almost every smog tech will tell you to replace it if you fail. It COULD be bad. But unlikely. I would spend money on some easy stuff like front 02 sensor and cleaning MAF sensor. If those sensors skew, you're gonna have falsified rich/lean conditions which affects all that. I don't have much experience in smog diag, but I do know 4Runner (or really Toyota) cars failing are rare. Normally something takes them out vs just dying. But 21 years is a long time.

 

[MarkBlack]

I know a place in garden grove that will pass you for $175. May be a cheaper solution until you can get the problem fixed.
My 97 was 1 level away from failing. (I failed because of tape on a vacuum hose) I took it back the second time and I ran some of the lucus oil cleaner thats suppose to lower emissions and it didnt do a damn thing.

 

[mkzg]

I’ve cleaned the MAF before smogging. I haven’t changed any o2 sensors...I looked at real-time on them in my scanner, and both function.

History of the vehicle:
Got it from Houston with a supercharger on it, took that off for my other 97 that is my keeper, swaped Intake and supercharger, Once I smog this and register in California, I’ll be selling it.

It was grossly neglected as well, which I’ve brought the maintenance current. The cat looks to be replaced already at one point in its history. Could major carbon buildup in the cylinders cause these problems? Maybe there was additional buildup from the blower before?



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[T.Tech]

Carbon build up will contribute to higher nox. How are your fuel trims? A lean mixture will also have higher nox. I’ve heard of people mixing in a bottle of rubbing alcohol in their fuel tank to pass smog. The only way the vehicle has to reduce nox is the cat converter. Your vehicle doesn’t have egr does it.

 

[gamefreakgc]

I used to get cat problems right around smog time with my 2000. I used a bottle of Cataclean and that seemed to do the trick. YMMV.

https://www.amazon.com/Cataclean-12..._1_3?keywords=cataclean&qid=1573618468&sr=8-3

Second vote for cataclean. Worked great for me.

 

[mkzg]

Carbon build up will contribute to higher nox. How are your fuel trims? A lean mixture will also have higher nox. I’ve heard of people mixing in a bottle of rubbing alcohol in their fuel tank to pass smog. The only way the vehicle has to reduce nox is the cat converter. Your vehicle doesn’t have egr does it.

Ill pull the fuel trims, not sure what they are right now. No, 3.4l 4runners do not have EGR.

Adding rubbing alcohol to the fuel will reduce Nox?

 

[mkzg]

Second vote for cataclean. Worked great for me.

are these votes for vehicles that initially failed a smog, then passed after using it?

 

[mkzg]

Live data

Fuel system - CL
Calc load - 14.5-14.9% fluctuating
Ect - 185 f
STFT b1- -3.1-1.6% fluctuating
LTFT B1 - 1.6%
Rpm - 690-709
Speed - 0
Spark advance - 8.5-19 fluctuating
Iat - 91f
MAF - .46-.47 lb/min
TPS - 9.8%
02 b1s1 - .155- .790 v
STFT b1s1 - -0.8 - 3.1% fluctuating
02 b1s2 - .060 - .845 v
STFT B1s2 - 99.2% fixed





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[The Cold War Kid]

Replace the PCV valve. Check the air cleaner.

Pour 3 fluid ounces of pure acetone (available at walmart as nail polish remover) per 10 gallons of gas into your tank. Drive around a while to mix in the acetone. Get it smogged again - you'll pass with flying colors

 

[mkzg]

Replace the PCV valve. Check the air cleaner.

Pour 3 fluid ounces of pure acetone (available at walmart as nail polish remover) per 10 gallons of gas into your tank. Drive around a while to mix in the acetone. Get it smogged again - you'll pass with flying colors

PCV and air cleaner is new already before smog was done. Ill get the acetone and test that out!

 

[19963.4lsr5]

PCV and air cleaner is new already before smog was done. Ill get the acetone and test that out!

I put 4oz in my Saturn SL (40-45mpg beater car) and 4Runner every fill up. Which reminded my I need to get more.


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[gamefreakgc]

Live data

Fuel system - CL
Calc load - 14.5-14.9% fluctuating
Ect - 185 f
STFT b1- -3.1-1.6% fluctuating
LTFT B1 - 1.6%
Rpm - 690-709
Speed - 0
Spark advance - 8.5-19 fluctuating
Iat - 91f
MAF - .46-.47 lb/min
TPS - 9.8%
02 b1s1 - .155- .790 v
STFT b1s1 - -0.8 - 3.1% fluctuating
02 b1s2 - .060 - .845 v
STFT B1s2 - 99.2% fixed

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Your fuel trims are good. Also interesting to see your spark advance flip flop around like that, my old tired engine did that too. Replacement JDM doesn't do it at all.

The cataclean product also contains acetone. And yes, I used it from the perspective that I was going to fail smog and the product allowed me to pass. My cat smelled like rotten eggs (sulfur) and then I used the product and it cleaned it right up. At this point you really can't go wrong trying since you failed the first go around anyway.

 

[trackntrail]

Your fuel trims are good. Also interesting to see your spark advance flip flop around like that, my old tired engine did that too. Replacement JDM doesn't do it at all.

The cataclean product also contains acetone. And yes, I used it from the perspective that I was going to fail smog and the product allowed me to pass. My cat smelled like rotten eggs (sulfur) and then I used the product and it cleaned it right up. At this point you really can't go wrong trying since you failed the first go around anyway.

Did you smog your truck with cataclean in the tank? Or run the tank of cataclean through and then smog it on fresh gas?

 

[19963.4lsr5]

Here is what I use for acetone. I have a qt can I suck it out of. .

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[gamefreakgc]

Did you smog your truck with cataclean in the tank? Or run the tank of cataclean through and then smog it on fresh gas?

Run it through the tank completely then refill with gas & smog.

 

[T.Tech]

I thought there was a year that it had egr but I might be thinking of another vehicle with a 5vz. I owned a vehicle that threw the mil for the catalytic converter below threshold when I used anything but shell 91 octane fuel, I believe the additives in helped clean the converter and keep it above its limit.

 

[4Reak Show]

I thought there was a year that it had egr but I might be thinking of another vehicle with a 5vz. I owned a vehicle that threw the mil for the catalytic converter below threshold when I used anything but shell 91 octane fuel, I believe the additives in helped clean the converter and keep it above its limit.

I'm fairly certain no 4Runner 3.4's have EGR. Some year CA Tacoma 3.4's do I believe. Something about an SUV being a passenger car vs a truck and having different standards. I read it somewhere.

Here's where I saw it
https://people.well.com/user/mosk/images/Early_Tacoma_ECUs_v2.pdf

Someone compiled a list and it says 2wd Tacomas have EGR. 4wd don't apparently. At any rate, if OP doesn't have it, it makes no difference.

 

[TheDurk]

I'm fairly certain no 4Runner 3.4's have EGR. Some year CA Tacoma 3.4's do I believe. Something about an SUV being a passenger car vs a truck and having different standards. I read it somewhere.

Here's where I saw it
https://people.well.com/user/mosk/images/Early_Tacoma_ECUs_v2.pdf

Someone compiled a list and it says 2wd Tacomas have EGR. 4wd don't apparently. At any rate, if OP doesn't have it, it makes no difference.

No OBDII 5VZ-FEs have the EGR. Since no 4Runners before 1996 had the 5VZ-FE, no 4Runners with that engine had the EGR as all are OBDII. Pre-1996 T-100s with the 5VZ-FEs have it, for example. Those little elbows with the caps on the top of the throttle body connect to the EGR when they are present.