cEElint

went to smog the pickup today.. bam, failed.. wtf?!? passed w/ flying colors 2 yrs ago w/ very low numbers... still had very low numbers except one test

91 Regular cab, 22r-e, 193k miles

15mph HC: max 133, meas 12... CO: max .59, meas .01... NO: max 1050, meas 1224

25mph HC: max 113, meas 13... CO: max .74, meas .01...NO: max 910, meas 80

whats causing me to read so high on the 15mph and read so low at 25mph on the NO test?

matstaley

Ditch California.

bob200587

What's 15 and 25 mph testing? Is the car moving at those speeds when it is done?

cEElint

moving out of CA isnt an option right now.. lol.. the smog test is done on a dyno here

1800's kinda guy

usually an oil change, spark plug change, running half a can of seafoam through your intake, and the other half in your gas tank will help greatly.

1800's kinda guy

oh, and after putting sea foam through your intake, it will bog down, and blow white smoke for a while.

93toyrunner2

x2 on the seafoam in the intake. Be sure that you use 1 oz of Seafoam per gallon of gas in your tank, otherwise, you are wasting your time.

GO_BLUE!

also check your timing. If you've advanced your timing, it will increase your emissions, particularly No2. I always run Seafoam through the brake booster line one or two days before smog. It truly does help.

TNRabbit

Have you changed tire size or gear ratios since then? I've heard of a few folks temporarily running small tires for smog testing to raise their rpm which somehow changes how the test readings....

bob200587

Sounds expensive.

blake.nemitz

it might not be a good idea but here last week in CO I failed 3 times for NOx. i retarded the timing to 0 degrees and it passed. also if you dont need 91 octane dont run it. run the cheapest gas you can burn. i typically run 87.

scope103

The vast majority of NOx problems are EGR related (that is THE purpose of the EGR system). So if SeaFoam helps, it was only by accident.

Run through the tests in the FSM; it seems likely you the EGR signal is not getting through at some point. One place to look on our older trucks is where the exhaust is ported from the EGR into the manifold. The port can get sufficiently gunked up that the exhaust can't get through into the manifold. That could explain why you are getting better results at the higher dyno speed (more flow), and it could even explain why SeaFoam might actually help a little (by knocking off a little of the gunk).

But the easy and effective route is to clean up the connection. Mine is a 3VZE, so it is a matter of removing the plenum (upper intake manifold), but I'm sure the 22re is no more difficult.

smogman

Changing oil and spark plugs are maintenace not repairs. This will do nothing to fix NOX levels.

Scope103 is 100% correct.

To get an accurate idea of whats going on, I need co2 and o2 levels too. These level's are very important to figure out whats going on.

sb5walker

Two things may be contributing to your high Nox. Nox is formed when combustion temps are high. Lean running will create high combustion temps, and your motor is running VERY lean (extremely low HC and almost no CO). How many miles are on your O2 sensor? If 90k miles or more, you maybe need to replace it - use a Denso direct-fit. Try sparkplugs.com or get the part # from there and search Amazon for denso and the part number. Also there could be a crack in one of the rubber bends of the air hose that runs from the air meter to the throttle body, which would allow air to bypass the meter, so it would tell the computer that less air is going into the motor than really is. Or, perhaps the air meter VS spec is out of range.

EDIT: Also, check that your idle rpms are not too low. You may need to clean the throttle body, upper and lower air bypasses, throttle plate, with a good throttle body (not carb) cleaner. Don't allow the solvent to wick along the throttle plate shaft into the tps or otherwise get on or in the tps; that could kill it.

The other cause of high nox is, as mentioned, a malfunctioning EGR. The fact that your nox is fine at one rpm and bad at another does potentially point to egr trouble. There are two vac lines that run from the throttle body to the egr modulator: one is active when the throttle is open only a little, and both are active when the throttle is opened further. It's possible for one of the tubes to be clogged with gunk, it's possible the two lines are crossed between throttle body and modulator, possible that the modulator is bad, or possible that the filter inside the modulator is clogged. The fsm suggests trying to blow that out with compressed air. Here's the fsm chapter to troubleshoot the egr:
Trucks originally sold in CA: http://www.ncttora.com/fsm/1993/engine/19egrsy.pdf
Fed/Canada trucks: http://www.ncttora.com/fsm/1993/engine/18egrsyste.pdf

A post on egr troubleshooting: https://www.yotatech.com/51539693-post60.html

Here are a couple good egr articles, but they are not specific to toyotas:
http://www.motor.com/magazine/pdfs/082009_04.pdf
http://www.motor.com/magazine/pdfs/092009_04.pdf

smogman

[quote=sb5walker;51812984]Two things may be contributing to your high Nox. Nox is formed when combustion temps are high. Lean running will create high combustion temps, and your motor is running VERY lean (extremely low HC and almost no CO). How many miles are on your O2 sensor? If 90k miles or more, you maybe need to replace it - use a Denso direct-fit. Try sparkplugs.com or get the part # from there and search Amazon for denso and the part number. Also there could be a crack in one of the rubber bends of the air hose that runs from the air meter to the throttle body, which would allow air to bypass the meter, so it would tell the computer that less air is going into the motor than really is. Or, perhaps the air meter VS spec is out of range.

I'm not sure how you figure his truck is running lean? These are Post cat readings and you do not know the o2 and the co2 levels. He could have 0% o2 and 14.9% co2. It's impossible to determin is his motor is lean by looking at 2 readings. this is why for a Lambda calculator you need all 5 readings. This calculation works for post cat numbers and is 100% accurate for your A/F ratio. try it http://www.916smog.com/lambda-calculator.html

I bet when he types in his numbers it's not lean. This is why I said we need all the numbers to figure out what his problem is.

sb5walker

On this series truck, seeing virtually zero hydrocarbons and zero carbon monoxide is almost always an indication of lean running. Even with a brand new cat it's rare to see numbers that low on a 193k mile 22RE or 3VZE unless it's running really lean. Not impossible, but very rare. So I'll stand by what I said. I'll bet the spark plugs, if they have been in the motor for at least a few k miles, will show white deposits, which will confirm a lean condition.

smogman

Everyone has an opinion.

But without doing a lambda calc your still guessing.

This is why so many people get lost in diagnosing their vehicles. They get partial information and then take a guess and go into left field.

I have an opinion on what's causing his problem and it's way different that your's, but I don't want to steer him in the wrong direction just because I wanted to guess.

If I had to guess at something, I would take my 22yrs of experience and say your guess of running lean is 100% wrong, in doing so I can not steer you wrong on fixing your truck. I will explain why. On a motor that has unmetered air entering into a system it is a set amout of air (the leak is one size). A motor flows very little air at idle and a lot or air at cruise speeds. So this will cause a unmetered air ratio. something like 100to1 at idle and 2000to1 at cruise. If your unmetered leak was so big to effect a lean condition at cruise it would be big enough to kill the motor at idle. Unmetered air is the same as a vacuum leak on a carborated car. And if your theory was correct the leak would not go away at 25 mph. You can not have a leak that is not there at idle,starts to leak at 15mph and then starts leaking again at 25 mph.
This is why I do not give opinions, It allows other people to argue with you.

I see toyota trucks have low hc and low co all the time. Take a 84 toyota (carb) truck with a new cat and a working AIS system and you will see these numbers. Disconnect the AIS system and you will see C.O. spike to 2.5-4%. Does this mean the motor is now running rich? No. The A/F ratio is actually the exact same. It means the O2 went to 0% and CO2 went to 12% and the cat quite working. H.C can still be low. If these were precat readings I could get on board with your guess but unfortunatly these are post cat readings and a converters job is to convert one thing into another. HC,CO,and NOX are converted to CO2 and without the CO2 and o2 reading you can only guess at it.

Use the Lambda calc for any car. It is awesome. I was very sceptical about it when I saw it but then I got a chemistry lesson. Then I figured the converter does not burn anything, it just converts. There is no other way to take a post cat reading and find your a/f ratio.

Philbert

iTrader: (2)

I'm glad I found this thread!

I have an 87 4runner with 22RE and failed smog twice this past month.

When I failed the first time, the guy recommended new plugs, O2, timing, cat, and clean out the EGR. I did everything, and wires, but did not address the EGR (it's a PITA to get to!). I failed again, but only failed on the 15 MPH test, as did the OP here. Again, he said check EGR.

So I took it out last night, and the vacuum modulator (cleaned filters with compressed air), and cleaned the EGR with carb cleaner. I also sprayed carb cleaner into the port for the EGR on the head, and the intake manifold.

I'm going to button it back up this weekend and do the FSM tests to see if it passes for the EGR and vacuum modulator.

I got a new EGR gasket from the auto parts store but it's only for the intake manifold side...is there no gasket for the head side of the EGR?

I'll be following this thread - good luck cEElint!

john4wd

Move to Indiana, NO emission tests here!!!!

smogman

You must live in a different Indiana. And you guys have safety checks too. not sure why everyone hates California and then points to the smog check program. I don't know of very many states that don't have smog.

Yes I'm sure your county doesn't have smog checks but we have some of those too. They are usually small population.

http://cleanaircarcheck.com/