HellFish

iTrader: (5)

rich condition would drop the level for NOx and raise the CO level. his CO levels are low, so that would just about rule out the rich condition.

KA8

iTrader: (1)

Failing smog sucks! I was surprised my TT with idle problem passed smog just couple of days ago.

StiCk3

iTrader: (5)

exactly. The direct opposite occurs when the fuel mixture is lean. CO numbers drop while NOx numbers rise due to the higher combustion temps.

masagsxr

Yup.. it has to be the cat.... My cousin's car has the exact same story just like I mentioned on my previous post. We did everything as far as cleaning up the EGR, re-timed, cleaned throttle body, change plugs etc... and still failed.. As soon as he changed the cat, it past and the numbers were looooooooooow....

Here are some measurements of his 97 Prelude...
Failed the first time (Before cleaning EGR etc...)
15MPH
HC: Max = 55, Meas = 54
CO: Max = .50, Meas = .14
NO: Max = 437, Meas = 519 (Failed)

25MPH
HC: Max = 39, Meas = 38
CO: Max = .48, Meas = .06
NO: Max = 724, Meas = 576 (Passed)

Failed 2nd time after cleaning EGR etc.. but the result was better.
15MPH
HC: Max = 55, Meas = 49
CO: Max = .50, Meas = .08
NO: Max = 437, Meas = 623 (Failed)

25MPH
HC: Max = 39, Meas = 38
CO: Max = .48, Meas = .05
NO: Max = 724, Meas = 555 (Passed)

Sorry, i don't have the new results after it passed. I'll ask him to email it to me. He just called me the day it passed just to tell me it did heheheee.... The results I posted above were the ones from the email I got from him before.

6SOARER

iTrader: (20)

Listen to this guy ^^, he knows what he's talking about. Souds like your EGR isnt working properly. Maybe someone stuck a BB in the line to prevent it from working correctly. I hear a lot about ppl plugging or deleting the EGR to get more performance, Im not sure if this is true.

But by looking at your numbers, your HC's and CO's are really low. This doesnt indicate that your CAT is bad. If you would have high number throughout the board(HC,CO,NOx) it would defintely be your converter.

Make sure you have vacuum going to your EGR. Alot of times when i see a Toyota/Lexus fail for high NOx its either 1. a bad EGR modulator 2. Vacuum lines not routed right 3. Vacuum lines plugged..

6SOARER

iTrader: (20)

See these numbers show a worn/shot Catalytic converter. If you look at the MEASURED numbers compared to the MAX for the HC and NOx they are real close or even higher than the MAX, this shows that the cat is weak and needs to be replaced.

Now Fenderrubs and the numbers on the VIR above show that the NOx's are high and the HC's are low. This will indicate that the CAT is still ok and that you should look elsewhere for the problem.

sagikun

you guys are funny.. FENDERRUB, change your cat. you need a new one

chinaman

any updates on this. i got the same problem wit my ls400, even got new cats and still didnt pass for nox

sc300916

your car is difinitely running on the lean side. your vehicle don't have a air pump so your oxygen reading should be zero not .1 or you have exhaust leak in front of your cat. which will cause high nox. and no body ever mention about your o2 sensor. the o2 sensor is design to keep you at 14.7 to 1 all the time. if it is bias lean it will run rich and if it is bias rich it will run lean. in your case possible the o2 sensor is fix rich or bias rich. i hope this help. like other people said check for vacuum leaks it will cause a lean condition and high idle. check your egr system to see if it work. don't replace your cat. until you did all of the above. the cat. should be the last thing to be change if everything above don't fix it. by changing the cat. and not fixing it right even though most of the time it might pass but all you doing is just covering over the problem for now. good luck.

Johnnilam

iTrader: (1)

fenderub have you went back and got it retest? i'm having the same failed reading on my sc400 keep us updated. still trying to find a way to fix it thanks

jer_con

I vote EGR. You won't get a check engine light unless the sensor actually fails. I did my EGR and Throttle Body at the same time; just cleaned all the gunk out of both sides. I'm getting about 3 more miles to the gallon now too. If I were you I would clean TB, EGR and throw in a new set of plugs, maybe change the oil, new air filter etc. I bet that takes care of it without spending to much $$. Drive the hell out of it and get the motor good and hot before your next smog, it helps.

Not sure about the CAT but since we're lucky enough to be in CA you'll be paying an extra $100 - $150 for the stupid CARB stamp! Gotta love the People's Republic of California...ppptthhh.

imissmys14

Try the gaurnateeed pass stuff. Put it in your gas tank with full and drive around till it's empty and try again when I smog my ls4 the numbers went way down but I still failed n I tried the stuff one more time and I passed. it cleans out the whole system really. Try it first instead of spending hundreds it worked for me x2cans tho

Murder300

I failed my smog yesterday, due to high measurement of hydrocarbons, but it was the shop my mom works at who did the test, so I didn't get a readout cuz he ran the test twice, and that was the only thing he told me.. high hydrocarbons and aborted the test.
I have 174k, so I might just need a seafoam-like cleaning/tune-up. But it runs like a dream, cats still crackle&pop when I turn the car off.. so idk.
Is Seafoam bad for the 2jzge? I hear mixed opinions..
Not tryna sound like a n00B for not using the search button, but I need help. haha what would you do if it were your SC? I know it's hard to tell without the printout..

6SOARER

iTrader: (20)

The printout would help a lot. It depends how high the HC's were.

Hydrocarbons is unburned fuel, so anything that helps burn fuel will reduce HCs.

If it barely FAILED but a few points I say do a tuneup-plugs, wires oil change etc. But if it the HCs are high, the Catalytic Converter is shot.

Im not too sure about the Seafoam thing, I never done it before.

cbrasian

talk about bringing a old thread to life lol