failed smog .. high nox - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 06-25-2004, 08:13 PM   #1
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Apr 2004
Location: bay area, ca
Posts: 42
Thanks: 0
Thanked 0 Times in 0 Posts
xkeithx is on a distinguished road
Default failed smog .. high nox

just took my car in to get smogged, it passed everything but the nox. these are the following readings:

15mph max: 419 average: 57 measured: 713 FAIL
25mph max: 706 average: 50 measured: 614 pass

its a 96 bonneville se (non turbo) with 187k miles. im stupid and forgot to change the oil before taking it in, its gonna be at the 3k mark in about 100 miles. is there an EGR valve on the 96? i read somewhere that the 92 and up dont have egr, they have a 3 part cat instead, and one part of it gets rid of nox. well anyways, what do i need to do to get this thing to pass? the check engine light never comes on, so i was thinking maybe its an egr passage that could be clogged... but i dont know what the egr looks like or where its located. thanks a lot guys!
xkeithx is offline   Reply With Quote
Old 06-25-2004, 08:18 PM   #2
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Apr 2004
Location: bay area, ca
Posts: 42
Thanks: 0
Thanked 0 Times in 0 Posts
xkeithx is on a distinguished road
Default

oh one thing i forgot to mention.. every time i start the car i have to give it a little gas to get it to start. its only been doing this for a few weeks, but once i start it the engine revs up to like 2 or 3 k and then goes back to around 900 rpm. besides this start-up issue, the car runs beautifully.
xkeithx is offline   Reply With Quote
Old 06-25-2004, 08:23 PM   #3
Senior Member
Posts like a Corvette
 
Ol' Timer's Avatar
 
Join Date: Oct 2002
Location: New Jersey - Most of Our Elected Officials Have Not Been Indicted
Posts: 1,483
Thanks: 0
Thanked 0 Times in 0 Posts
Ol' Timer is on a distinguished road
Default

I got more questions than answers. When was the last time you replaced the spark plugs, ignition wires, air filter, gas filter, pcv valve, and (most of all) your O2 sensor???

I'm not saying that your EGR may be bad, but I figure your MIL(aka SES) light would have come on for that. Also I doubt not changing your oil with 3K on it caused you to fail the emissions test. Cleaning the Throttle Body also couldn't hurt.
Ol' Timer is offline   Reply With Quote
Old 06-25-2004, 08:42 PM   #4
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Apr 2004
Location: bay area, ca
Posts: 42
Thanks: 0
Thanked 0 Times in 0 Posts
xkeithx is on a distinguished road
Default

spark plugs , wires, pcv are all new.. only replaced a few months ago. the air filter hasnt been touched in a while, its not too dirty.. havent touched the gas filter or the o2 sensor. is there a way i can test the o2 or the pcv to see if they are faulty?
xkeithx is offline   Reply With Quote
Old 06-25-2004, 09:53 PM   #5
Senior Member
True Car Nut
 
Join Date: Dec 2002
Location: Sauk Centre, MN
Posts: 5,458
Thanks: 0
Thanked 0 Times in 0 Posts
OLBlueEyesBonne is on a distinguished road
Default

When my front oxygen sensor went bad in my SSEi the car was running dirty rich.
I didn't have a SES light either. I changed the o2 sensor on a hunch and my mpg'* went up about 60-70%.
OLBlueEyesBonne is offline   Reply With Quote
Old 06-25-2004, 09:53 PM   #6
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Apr 2004
Location: bay area, ca
Posts: 42
Thanks: 0
Thanked 0 Times in 0 Posts
xkeithx is on a distinguished road
Default

it says on the smog check vehicle inspection report that the oxygen sensor passed the functional check. i would think that if the o2 or fuel filter were bad that my emissions would have been higher for the hc and co readings as well. but the hc was below average at both 15 and 25 mph speed tests, and the co readings were:

15mph max: 0.48 ave: 0.02 meas: 0.05
25mph max: 0.46 ave: 0.03 meas: 0.03

i assume that the egr is the problem as its only function is to reduce nox, which it doesnt seem to be doing.
xkeithx is offline   Reply With Quote
Old 06-25-2004, 09:58 PM   #7
Senior Member
Posts like a Corvette
 
Ol' Timer's Avatar
 
Join Date: Oct 2002
Location: New Jersey - Most of Our Elected Officials Have Not Been Indicted
Posts: 1,483
Thanks: 0
Thanked 0 Times in 0 Posts
Ol' Timer is on a distinguished road
Default

Quote:
Originally Posted by xkeithx
is there a way i can test the o2 or the pcv to see if they are faulty?
Theoretically, if you pull the PCV Valve out and shake it and it rattles, it'* good. But my theory is, if you spent the time to take it out(and you don't know how long it'* been in there) just replace it. One of the benefits of replacing an old 02 sensor, is better gas mileage(along with better emissions). Please note that most members here strongly recommend the Delco brand O2 sensor(with Bosch being a no-no). Good Luck.
Ol' Timer is offline   Reply With Quote
Old 06-26-2004, 01:04 AM   #8
Member
Posts like a V-Tak
Thread Starter
 
Join Date: Apr 2004
Location: bay area, ca
Posts: 42
Thanks: 0
Thanked 0 Times in 0 Posts
xkeithx is on a distinguished road
Default

could you tell me what the gm part number is that i would need from gmpartsdirect.com?
xkeithx is offline   Reply With Quote
Old 06-26-2004, 01:45 AM   #9
Senior Member
True Car Nut
 
Join Date: Dec 2002
Location: Sauk Centre, MN
Posts: 5,458
Thanks: 0
Thanked 0 Times in 0 Posts
OLBlueEyesBonne is on a distinguished road
Default

The GM part # is in techinfo. You'll need the POSN1 o2 sensor. But here it is anyway with the gmpartsdirect prices -courtesy of willwren:


1996 Vin# K,1 - POSN1
GM# 25312184 (AC Delco #AFS-75)
$34.07

Behind Cat POSN3
GM# 25312196 (AC Delco #AFS-97)
$56.94
OLBlueEyesBonne is offline   Reply With Quote
Old 06-26-2004, 01:52 AM   #10
Senior Member
True Car Nut
 
Join Date: Jun 2004
Location: Rochester, NY (college)
Posts: 6,182
Thanks: 0
Thanked 0 Times in 0 Posts
corvettecrazy is on a distinguished road
Default

When replacing the sensors should you replace both or just the front? While we are on the topic of emissions how long do CAT'* last?
corvettecrazy is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
NOX emission failure for 1998 grand prix gtp Sean_6969 Pontiac 3 01-23-2012 10:54 PM
Gross Pollluter, HIGH NOX sp4149 1992-1999 24 07-19-2007 03:35 AM
Failed NOx Help? kaps 1992-1999 16 09-08-2004 10:16 AM
bonnie failed the nox in emission test rrrddgy 1992-1999 4 03-01-2004 02:21 PM
Smog Test Results? billha 1992-1999 2 03-21-2003 12:56 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:50 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.