Help! NO levels way high on smog! I need to pass!

[youarenottricky]

as the title indicates, my NO levels are really high, indicating i'm a "gross polluter" lol. there are so no-name headers on it, but that's it. the guy let me slide with them, and he said they didnt affect it too negatively since my hydrocarbons were still within good limits. he said that it was probably my EGR, since that has a lot to do with NO levels. I got it looked at by a smog repair shop, and they said the EGR valve and vacuum are all fine.

sooooo, what do you guys think it is and what might i be able to do to get my NO levels to drop?

here's my report card:

MAX = Maximum Allowable Emissions
GP = Gross Polluter Limits
MEAS = Amount Measured

HC (PPM)

15 MPH - MAX: 118 - GP: 293 - MEAS: 25

25 MPH - MAX: 93 - GP: 243 - MEAS: 17


CO (%)

15 MPH - MAX: 0.75 - GP: 2.25 - MEAS: 0.01

25 MPH - MAX: 0.63 - GP: 2.13 - MEAS: 0.01


NO (PPM)

15 MPH - MAX: 799 - GP: 2002 - MEAS: 2217

25 MPH - MAX: 738 - GP: 1802 - MEAS: 2231


as you can see, my NO levels are jacked. :naw:

here's the rest:

CO2 was 14.6% for 15 and 25 MPH.

O2 was 0.6% @ 15 MPH and 0.8% @ 25 MPH

RPM @ 15 MPH was 1741 and @ 25 MPH was 1913

The car i'm trying to smog is a 91 5 speed coupe with a 93 ka24de in it.

[hassanbakar123]

most likely something with the egr.(check vacuum)
whats the CO2?
(I'm a licensed smog tech.)

[youarenottricky]

most likely something with the egr.(check vacuum)
whats the CO2?
(I'm a licensed smog tech.)

i took it to a shop and had the check the egr and egr vacuum and everything is fine with it. i updated the OP with CO2, O2, and RPM levels.

[idlafie]

Not,

What year is your car?? S13 or S14??

On S13's there are two soleniods hidden behind the engine & close to the O2 sensor which regulate & control the BPT & EGR valve. If these soleniods get clogged / dirty or fail, they won't allow hot exhaust gases to flow back into your combustion chamber thru the EGR Valve. The hot combustion gasses that flow back into your combustion chamber are used to regulate the formation of NOX gasses in your exhaust. Click on the attached link for a better explanation.

Mopar Magazine | Reducing NOx-ious Emissions (http://www.moparmagazine.com/2009/march-april/reducing_nox-ious_emissions)

Anyhow, hope this explanation helps you to understand how NOX gasses are formed. Good luck with finding & fixing the problem in your EGR system.

Hope this helps...

ID

[youarenottricky]

Not,

What year is your car?? S13 or S14??

On S13's there are two soleniods hidden behind the engine & close to the O2 sensor which regulate & control the BPT & EGR valve. If these soleniods get clogged / dirty or fail, they won't allow hot exhaust gases to flow back into your combustion chamber thru the EGR Valve. The hot combustion gasses that flow back into your combustion chamber are used to regulate the formation of NOX gasses in your exhaust. Click on the attached link for a better explanation.

Mopar Magazine | Reducing NOx-ious Emissions (http://www.moparmagazine.com/2009/march-april/reducing_nox-ious_emissions)

Anyhow, hope this explanation helps you to understand how NOX gasses are formed. Good luck with finding & fixing the problem in your EGR system.

Hope this helps...

ID

thanks for the info, and yes, it is an s13

[Monooxide]

Every S13 I have worked on and removed those solenoids in the back have had giant dry rot holes in the vacuum lines on those solenoids.

You can also try pulling timing out as NOx emissions will go down with less timing. Also, a richer mixture will bring down NOx levels, but CO and HC levels will rise. High NOx levels mean your probably lean.

I just read all of this in my Electromotive standalone manual. We don't have emissions luckily.

Good luck.

[youarenottricky]

Every S13 I have worked on and removed those solenoids in the back have had giant dry rot holes in the vacuum lines on those solenoids.

You can also try pulling timing out as NOx emissions will go down with less timing. Also, a richer mixture will bring down NOx levels, but CO and HC levels will rise. High NOx levels mean your probably lean.

I just read all of this in my Electromotive standalone manual. We don't have emissions luckily.

Good luck.

anyone have pictures or a walkthrough on how to replace those solenoids and/or pulling the timing out? i'm pretty sure i'm already running rich, it smells that way at least lol... not sure if running lean smells the same, since i'm a semi noob with cars, but im pretty sure it doesn't and my friend said it smelt rich as well

[ryguy]

The EGR may be fine, but the EGRC-BPT is probably the culprit. I just bypassed mine to pass smog, but I live in Indiana and don't have visual inspection. My numbers were the same as yours, BTW.

http://i2.photobucket.com/albums/y17/ryguy32789/ECCS1.jpg

[youarenottricky]

The EGR may be fine, but the EGRC-BPT is probably the culprit. I just bypassed mine to pass smog, but I live in Indiana and don't have visual inspection. My numbers were the same as yours, BTW.

http://i2.photobucket.com/albums/y17/ryguy32789/ECCS1.jpg

thanks everyone for the amazing help! Ryguy, how do i bypass the BPT? The guy who usually smogs me can be lax on the visual (he let me pass vis with no name headers, even after pointing them out to me :goyou: lol), so i think he might overlook this too. and what did your levels change to after the bypass? did CO and HC raise, but NO lowered? or did the NO just lower? could the NO levels have anything to do with a bad Cat either? im not sure if it is bad, but i was going to swap it with a known good one and try that, but that might take a bit so the bypass would be a quicker fix if it works

[blackrms13]

have u try lifting the valve on the EGR?
engine should die if i lift it

i had to get the whole IM off to clean out the whole EGR thing...then the valve worked, but only manually

[youarenottricky]

have u try lifting the valve on the EGR?
engine should die if i lift it

i had to get the whole IM off to clean out the whole EGR thing...then the valve worked, but only manually

i took to a smog repair shop and they both egr valve and vacuum, and said the egr is fine. would you have to take the valve completely off to test it? because they didn't

[zjoanyg]

hey bro, im in the same boat as u... i replaced both my egr valve and the egrc-bpt valve... went back to the smog shop and the numbers were pretty much the same for me.... so im not too sure if it'll be the same for u... there is a vacuum line that goes from underneath the egrc-bpt to the egr valve.... make sure its not pinched...... i haven't tried anyting else yet though...

[roboticnissan]

There should be a passing smog for dummies thread

[zylvia213]

Dam a lot of good info on here....

[youarenottricky]

hey bro, im in the same boat as u... i replaced both my egr valve and the egrc-bpt valve... went back to the smog shop and the numbers were pretty much the same for me.... so im not too sure if it'll be the same for u... there is a vacuum line that goes from underneath the egrc-bpt to the egr valve.... make sure its not pinched...... i haven't tried anyting else yet though...

I think I'm going to try a pre-test after i bypass the bpt valve tomorrow... if i do i'll let you guys know how it goes... @zjoanyg do you have an s14 or s13? i talked to ryguy more about how to bypass it on an s13, and he told me to pull out and connect the two vacuum lines that go into the top of the bpt valve (they kinda form a V shape on top of the valve)... that's what i'm going to try... he also said it would idle pretty rough since the egr valve isn't meant to be open under 2000 rpm... i hope the pre-test goes well! if it does, then ill retest for my certificate! ill post results here once i get it done

[youarenottricky]

this is the diagram that ryguy sent me:

http://i2.photobucket.com/albums/y17/ryguy32789/EGRbypass.jpg

the red line shows the new vacuum line path after you connect the lines that go into the top of the egrc-bpt together. you can see the lines going into where they're supposed to on the bpt valve right underneath the vacuum "rainbow" lol... im attaching a closeup of the original scan from the 1991 FSM so you can better see where the lines attach to the bpt valve

[ryguy]

Just a disclaimer, my method of passing NOx is only a band-aid, but it does work. Bypassing the EGRC-BPT will leave the EGR open at all times, and you'll have a rough idle. You'll have to put it back the way it originally was after you pass the sniffer.

[yukon]

i took to a smog repair shop and they both egr valve and vacuum, and said the egr is fine. would you have to take the valve completely off to test it? because they didn't

no, you dont have to take it off. if it is working, the other related valves are also working.

[redline racer510]

I can bet you that the vacuum lines going to the egr are worn out.

[zjoanyg]

i drive a 91 s13 hatch with a 94 swapped in... oh yeah, forgot to mention that my numers for the NO are around 1500..... just a couple hundred shy of u...

[singlecamslam]

I just came back fromt smog, same deal. Gross freaking poluter. As soon as i got home i noticed the EGR solenoid valve was unplugged, son of a bitch. But to be safe, i'm gonna clean the BPT valve and the EGR. Can i just spray some Intake cleaner in the vacuums of the EGR? Got a free retest so this one needs to count haha.

Also, would this shit play a big role in emmisions? http://forums.nicoclub.com/zerothread/254273

[yukon]

I just came back fromt smog, same deal. Gross freaking poluter. As soon as i got home i noticed the EGR solenoid valve was unplugged, son of a bitch. But to be safe, i'm gonna clean the BPT valve and the EGR. Can i just spray some Intake cleaner in the vacuums of the EGR? Got a free retest so this one needs to count haha.

Also, would this shit play a big role in emmisions? 1989-1994 240sx: AIV PAIR valve removal tutorial: Nissan Online Mechanic: Nissan Forums / Infiniti Forums - NICOclub (http://forums.nicoclub.com/zerothread/254273)

aiv? it helps for idle test . you need to use a pipe brush to clean the egr.

[singlecamslam]

this thing, i though it lets extra air into the cat to warm it up. Could this cause me to fail smog? my HC is 164 and max is 118. changing the cat. My NOX is 2425 haha. I'm planning in unleashing a can of intake cleaner into the egr vacuums and stuff.http://i200.photobucket.com/albums/aa37/oldskool916/stuff.jpg

[yukon]

the aiv only works during idle. since you live in california, it probably doesnt help since your ecu is being guided by 02 sensor during idle. iq is normally distributed leaving half the people with iq's lower than 100.

[singlecamslam]

Alright just to maybe help some people out. When i lift the diaphram on my egr the engine dies right away. But i took the EGR BPT valve off and the factory service manual says to plug one side up and apply vacum, i did that and found a leak. So hopefully thats the problem, i tried 3 different ones and they were all leaky, so check yours seems like they go bad.

[yukon]

Alright just to maybe help some people out. When i lift the diaphram on my egr the engine dies right away. But i took the EGR BPT valve off and the factory service manual says to plug one side up and apply vacum, i did that and found a leak. So hopefully thats the problem, i tried 3 different ones and they were all leaky, so check yours seems like they go bad.

You said your egr was unplugged during your smog test so why are you even wondering why you failed. You likely did the vacuum test wrong or your vacuum pump connections are leaking. Thread jacking just makes the thread confusing as hell to follow.

[pancakes562]

wow thats crazy! you hit 4 digits! lol

mines the other way around.. i got mine tested in long beach

HC (PPM)
15MPH MAX: 61 AVE: 34 MEAS: 71
25 MPH MAX: 37 AVE: 21 MEAS: 64



why are hc levels max higher in lancaster?

[youarenottricky]

wow thats crazy! you hit 4 digits! lol

mines the other way around.. i got mine tested in long beach

HC (PPM)
15MPH MAX: 61 AVE: 34 MEAS: 71
25 MPH MAX: 37 AVE: 21 MEAS: 64



why are hc levels max higher in lancaster?

my best guess would have been county, but long beach and lancaster are both la county... maybe just the area? i know they adjust smog laws in CA according to density of the population or something... bigger cities have tighter smog restrictions, whereas rural areas have way looser requirements... i heard some areas of CA don't even need a smog check at all... could very well be wrong or just off, if anyone knows please hook it up with some knowledge!