Failed Smog need help!!

[4wd_mofo]

Well the 99 4x4 V6 taco went in today to get smoged. CO2 is fine, HC and CO fine, it's the damn NO (PPM) whatever the frunk that means. I live in California and they are strict as a MOFO on in this bitch. Max value at 15mph is 512 and i ran a 685. Realized that i had the deck plate mod open, and closed it up to make it stock again. put some 91 octane in, ran it hard for about 60 miles then came back. Second go dropped from 685 down to 601.

The truck is stock, outside a K&N drop in and deck-plate mod, and 2.5" cat back piping with flow-master muffler. This bastard passed 2 years ago no problem. It's Got 197K miles on it, I've had it for 4 years, and put 54K miles on it. Only thing i can think of is to swap out the O2 sensors. IIRC there are only 2, one in front of the cat, one behind. Any help would be great, thanks!

[Wainiha]

NO is nitrous oxide.

Do you have a check engine light on?

Vacuum leak?

Clean MAF?

Do you cats rattle when hit(loose material inside)?

Bad O2 sensor?

Maybe Seafoam it.

[ShowStop]

High NOx readings are usually caused by high combustion temps and or a failing cat. One of the functions of the cat is to reduce the NOx levels. Assuming your cat is good due to the other readings and the comment about your deck plate, I'd look at a possible issue with the EGR not functioning correctly or the fuel mix is too lean.

Clean the MAF if you haven't already. You can buy specific MAF cleaner spray at the autoparts stores. NEVER touch the sensor element, just dowse it with cleaner and let it air dry. Next, check to be sure the EGR is opening and closing by drawing a vacuum on the top port. If you reach under the EGR (when cold), you should feel the diaphragm retract.

If you have never replaced the front O2 sensor, then it is due. They are only rated for about 100k miles of use anyways. www.sparkplugs.com has good prices on Denso OEM replacements or you can get factory OEM from www.toyotapartsales.com

Also, if you haven't done a tune-up recently, do that. Just changing the spark plugs and the oil has a noticeable effect on the smog performance. Make it a habit to do a tune-up and oil change before you get a smog check. You'll have far less issues. Don't forget to change the PCV valve also.

If none of that helps, then its probably time for a new cat. You can always inspect it with a flashlight to see if the honeycomb is largely intact with no deep holes.

[4wd_mofo]

Originally Posted by Wainiha

NO is nitrous oxide.

Do you have a check engine light on?

Vacuum leak?

Clean MAF?

Do you cats rattle when hit(loose material inside)?

Bad O2 sensor?

Maybe Seafoam it.

i changed the plugs and wires at 180k, should be fine. The cat hasn't even been on the truck for almost 2 years. i put it back on a month ago so the ECU would work with the O2 sensors to remember what a cat is like. No CEL, no codes, no leaks. Sense the other read outs on the smog are good the only thing i can see would be a problem with be a leak, or the sensors. it's $53 each on amazon.com right now, for replacement Denso o2's. gonna order them up and see how it turns out.

[4wd_mofo]

Originally Posted by ShowStop

High NOx readings are usually caused by high combustion temps and or a failing cat. One of the functions of the cat is to reduce the NOx levels. Assuming your cat is good due to the other readings and the comment about your deck plate, I'd look at a possible issue with the EGR not functioning correctly or the fuel mix is too lean.

Clean the MAF if you haven't already. You can buy specific MAF cleaner spray at the autoparts stores. NEVER touch the sensor element, just dowse it with cleaner and let it air dry. Next, check to be sure the EGR is opening and closing by drawing a vacuum on the top port. If you reach under the EGR (when cold), you should feel the diaphragm retract.

If you have never replaced the front O2 sensor, then it is due. They are only rated for about 100k miles of use anyways. www.sparkplugs.com has good prices on Denso OEM replacements or you can get factory OEM from www.toyotapartsales.com

Also, if you haven't done a tune-up recently, do that. Just changing the spark plugs and the oil has a noticeable effect on the smog performance. Make it a habit to do a tune-up and oil change before you get a smog check. You'll have far less issues. Don't forget to change the PCV valve also.

If none of that helps, then its probably time for a new cat. You can always inspect it with a flashlight to see if the honeycomb is largely intact with no deep holes.

yea, been running Royal purple since 155K miles, that was recently done. The cat is fine, when i pulled it 2 years ago it looked fine, and it just sat in the garage, doubt it went bad. I didn't even know we has PCV's on these. never even looked. I have cleaned the Throttle body 2 times, and never the MAF, and never the O2's. the stupid kid i bought the truck from with 144K miles took it to a shop that changed on only one side of the block (the easy side) spark plugs. So i change them every 30K. Should go get a PCV and check the EGR.O2's wouldn't hurt, been debating doing them cuz my MPG have been slowly getting worse.

thanks for the link but Amazon's got you beat :P

http://www.amazon.com/Denso-234-4162...1999&carId=001

[gotblika]

Not sure which one you need, but Amazon has the best price I think.

Denso 234-9001 Oxygen Sensor (Air and Fuel Ratio Sensor)

Denso 234-9003 Oxygen Sensor (Air and Fuel Ratio Sensor)

[4wd_mofo]

Originally Posted by gotblika

Not sure which one you need, but Amazon has the best price I think.

Denso 234-9001 Oxygen Sensor (Air and Fuel Ratio Sensor)

Denso 234-9003 Oxygen Sensor (Air and Fuel Ratio Sensor)

umm, those don't fit a 99 tacoma 3.4V6...

[gotblika]

Originally Posted by 4wd_mofo

umm, those don't fit a 99 tacoma 3.4V6...

oKKKKKKKKKKK

[4wd_mofo]

Originally Posted by gotblika

oKKKKKKKKKKK

dont get mad, get glad

Showstop, the PCV was covered in oil, looks old as hell and kinda makes a little noise when i shake it. Sounds like its nearing the end of it functionality. The hose that was attached to it as well is cracking at each end so im going to replace both, cheap fix but i think over all the O2's are going to get me to pass.

Also, how am i suppose to check the EGR? im a little confused by your instructions.

[Wainiha]

Blow through the PCV only one direction will allow airflow IIRC, if it's good.

[tacoma2k]

Originally Posted by 4wd_mofo

Also, how am i suppose to check the EGR? im a little confused by your instructions.

The 3.4l V6 dosen't have a EGR system on it.

[TacoDell]

^ that's a fact

[thehackman15]

Originally Posted by tacoma2k

The 3.4l V6 dosen't have a EGR system on it.

I wish.

[4wd_mofo]

Originally Posted by TacoDell

^ that's a fact

lol, you were suppose to say " is that a fact?"

[ShowStop]

you can verify if you have an EGR system by looking at the emissions sticker under the hood. All California emissions vehicles will have an EGR.

The EGR is a valve with a round metal cap on it near the back of the engine. On the top, there is a vacuum line that goes to the center of the cap. This opens and closes the EGR valve. Using either a vacuum gauge or just some kind of vacuum pump, draw a vacuum on that line to make sure the EGR opens and closes.

[4wd_mofo]

Originally Posted by ShowStop

you can verify if you have an EGR system by looking at the emissions sticker under the hood. All California emissions vehicles will have an EGR.

The EGR is a valve with a round metal cap on it near the back of the engine. On the top, there is a vacuum line that goes to the center of the cap. This opens and closes the EGR valve. Using either a vacuum gauge or just some kind of vacuum pump, draw a vacuum on that line to make sure the EGR opens and closes.

very true, I live in CA, and that is where the truck is from. It has an EGR, I can clearly see it. I just sold my MR2 spyder yesterday, so i got $$ now and will be buying 2 new O2 Sensors. I'll let you know the outcome of the newest smog when i take it next week. I believe the O2 sensors are the originals, due to the lack of maintenance before i bought the truck with 144K miles.

P.S. how was big bear? if my lift and tires where installed i would have gone but i needed to sell the car first for the new rear suspension...

[So.Cal Taco]

Run a tank full of Chevron Get it in the system you will see a big diff on your test my Brother owns a Test only Station.

[4wd_mofo]

Originally Posted by So.Cal Taco

Run a tank full of Chevron Get it in the system you will see a big diff on your test my Brother owns a Test only Station.

where you located? I might bring my taco by

[simigeology]

I would replace your front O2 sensor. I had the same issue with high Nox and 200K in mileage.

[4wd_mofo]

Originally Posted by simigeology

I would replace your front O2 sensor. I had the same issue with high Nox and 200K in mileage.

they are only $53 on amazon including shipping. Im going to do both, do you know if the front one is different from the rear one? gotta find some time to get under the taco when it's under 100 degrees outside...

[Wainiha]

Originally Posted by 4wd_mofo

they are only $53 on amazon including shipping. Im going to do both, do you know if the front one is different from the rear one? gotta find some time to get under the taco when it's under 100 degrees outside...

Don't know about your year but CA emissions vehicles are different and I believe at one point they all switched. Front O2 was replaced with A/F sensor.

I have a 2000 taco CA emission spec. The front sensor is an Air/Fuel and the rear is an O2. 250$ for the front and 100$ for the rear.

[4wd_mofo]

Originally Posted by Wainiha

Don't know about your year but CA emissions vehicles are different and I believe at one point they all switched. Front O2 was replaced with A/F sensor.

I have a 2000 taco CA emission spec. The front sensor is an Air/Fuel and the rear is an O2. 250$ for the front and 100$ for the rear.

how can i tell if it's a Air/Fuel vs. O2. And my understanding is that any O2 is an Air/Fuel...

[simigeology]

I went through www.sparkplugs.com that Showstop mentioned above. I called them for my truck since Denso had several different part numbers. Based on their website and your truck their are 3 different part numbers for the front and 4 for the back. They all say 02 sensor. When I bought mine the different part numbers were related to the length of the electrical wire. I measured the electrical wire and called in the measurement. www.sparkplugs.com matched it up and It was delivered in two days. I believe they came out of Corona so you being in Diamond Bar might be one day delivery.

[4wd_mofo]

Originally Posted by simigeology

I went through www.sparkplugs.com that Showstop mentioned above. I called them for my truck since Denso had several different part numbers. Based on their website and your truck their are 3 different part numbers for the front and 4 for the back. They all say 02 sensor. When I bought mine the different part numbers were related to the length of the electrical wire. I measured the electrical wire and called in the measurement. www.sparkplugs.com matched it up and It was delivered in two days. I believe they came out of Corona so you being in Diamond Bar might be one day delivery.

oh thank god. I just looked at the o2's on my taco, the part numbers do not match the ones on Amazon.com. However, the ones on sparkplugs.com do match up with the ones on Amazon. i see there are 4 wires coming out of each O2. I guess i'll measure then order both.

[4wd_mofo]

Now here's the kicker, a month ago my numbers for the NO(PPM)
15mph test=685 Max allowed is 512
25mph test=479 Max allowed is 765

So i plugged up the Deck plate mod, put the truck back to stock minus the K&N drop in filter, and the flowblaster exhaust. Ran $15 worth of 91 octane and drove the truck hard for a day. Returned the next day and got these numbers
15mph test=601 Max allowed is 512
25mph test=505 Max allowed is 765

So again i failed the second test. got the new O2's in, a new vac line and PCV valve, runs great, no CEL and my MPG seems to be a little better. Drove for about 4 days after i replaced them and reset the ECU (unplugged the neg on the bat). I got to another Smog only station (just incase the one i was at wasn't working correctly) and i get these numbers

15mph test=676 Max allowed is 512
25mph test=540 Max allowed is 765

WTF?!?! it got worse after i replaced the O2's! So now, i'm going to change out the spark plugs (even tho there is only 14-16K on the ones in there now) And run a can of sea foam thru the Brake vac line into the intake manifold and some in the tank. Maybe run some 91 octane again, seemed to help. I'm out of ideas, need to get this smogged asap. The worst thing is, i found my smog report from 09, about 19K miles ago, I got these numbers...

15mph test=142 Max allowed is 512
25mph test=8 Max allowed is 765

[thehackman15]

Just dealt with the same exact deal. Check your egr valve and the modulater. Replace if needed or try and clean them out.

[4wd_mofo]

Originally Posted by thehackman15

Just dealt with the same exact deal. Check your egr valve and the modulater. Replace if needed or try and clean them out.

You had 600+NO(PPM) readings? where were they? I got a can of MAF cleaner, going to do that and the SeaFoam tomorrow. How do i clean the EGR? take all the hoses off and blow it out with my compressor?

[thehackman15]

Originally Posted by 4wd_mofo

You had 600+NO(PPM) readings? where were they? I got a can of MAF cleaner, going to do that and the SeaFoam tomorrow. How do i clean the EGR? take all the hoses off and blow it out with my compressor?

Yes I did I would fail the 15mph test by leaps and bounds then the 25mph test I would pass. The egr is bolted to the back of the intake manifold. There are 2 bolts holding it onto the manifold and 2 bolts holding the tube to that. If you take it off you can see a bunch of carbon build up and crap in it, but having cleaned my once before i just said screw it and bought a new one from toyota. The modulator has 3 vacuum lines coming off of it and one on the bottom that attaches to the egr. These are all on the back of the motor near the firewall. and no blowing it out with an air compressor wont get that stuff off, you'll have to remove it and hit it with some carb cleaner or something. I've also heard of people soaking the egr in gas, but I don't know about all that.

[4wd_mofo]

Originally Posted by thehackman15

Yes I did I would fail the 15mph test by leaps and bounds then the 25mph test I would pass. The egr is bolted to the back of the intake manifold. There are 2 bolts holding it onto the manifold and 2 bolts holding the tube to that. If you take it off you can see a bunch of carbon build up and crap in it, but having cleaned my once before i just said screw it and bought a new one from toyota. The modulator has 3 vacuum lines coming off of it and one on the bottom that attaches to the egr. These are all on the back of the motor near the firewall. and no blowing it out with an air compressor wont get that stuff off, you'll have to remove it and hit it with some carb cleaner or something. I've also heard of people soaking the egr in gas, but I don't know about all that.

Good looking out, i'll check that today when i'm working on the taco. maybe tues or weds i can re-smog the truck and see how things are.

[Jomentum]

NOx is caused by high combustion temperatures:

The egr releases exhaust back onto the intake, and displaces the amount of combustible matter in the cylinders.Because NOx forms primarily when a mixture of nitrogen and oxygen is subjected to high temperature, the lower combustion chamber temperatures caused by EGR reduces the amount of NOx the combustion generates.

The EGR is either clogged (passage between the valve and intake)
or the Vacuum system is not working properly.

easy way to test EGR valve, is to pull a vacuum line on the intake, and use it directly on the EGR valve, the engine should run rough or stall out.

The other three components to check for the EGR system, are the EGR vacuum modulaor, the Vaccum switching valve, and the Engine Computer.