Failed Emissions... :-(
Thread Starter
Race Director
Joined: Aug 2003
Posts: 11,043
Likes: 3
From: San Jose Pat Tillman - American Hero
Failed Emissions... :-(
Went to a shop today to get the '96 tested since it's due in July. The guy didn't care about the LT headers...there was hardly a visual component at all. It was when the 15mph rolling test began that my problems started. I got the following results:
__15mph Test__
HC (ppm) -- Max=52; Avg=9; Measured=13 --> Pass
CO (%) -- Max=0.49; Avg=0.02; Measured=0.01 --> Pass
NO (ppm) -- Max=424; Avg=57; Measured=654 --> FAIL
Sooo.... Looks like I maybe need new cats?
__15mph Test__
HC (ppm) -- Max=52; Avg=9; Measured=13 --> Pass
CO (%) -- Max=0.49; Avg=0.02; Measured=0.01 --> Pass
NO (ppm) -- Max=424; Avg=57; Measured=654 --> FAIL
Sooo.... Looks like I maybe need new cats?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
hm... is yours an LT1 or LT4?
If it's an LT4, the NOX won't care, cause there ain't no EGR... but the LTs will KILL and LT1 without working EGR.
Judging from the rest of your numbers, you are experiencing EGR withdrawls.
If it's an LT4, the NOX won't care, cause there ain't no EGR... but the LTs will KILL and LT1 without working EGR.
Judging from the rest of your numbers, you are experiencing EGR withdrawls.
Thread Starter
Race Director
Joined: Aug 2003
Posts: 11,043
Likes: 3
From: San Jose Pat Tillman - American Hero
It's an LT4... Someone in OT recommended a product called "Seafoam", and I thought I read somewhere (about a year ago) about putting a little alcohol (can't remember which kind, though - Isopropyl, methanol, ethanol, etc.) in the gas tank to "help".
Melting Slicks
Joined: May 2002
Posts: 2,670
Likes: 4
From: Severna Park MD
Originally Posted by Perfusion
It's an LT4... Someone in OT recommended a product called "Seafoam", and I thought I read somewhere (about a year ago) about putting a little alcohol (can't remember which kind, though - Isopropyl, methanol, ethanol, etc.) in the gas tank to "help".
Be careful about how you put it in to the car. When I tried it my HC count blew up. I think I had too much alky and the O2s sensing lean made the PCM over compensate and go rich. The exhaust smelled clean but the CO numbers were sky high.
Alcohol shouldn't affect the NOX numbers, it should affect the HC count.
Your LT4 doesn't use the EGR. So what is wrong?
Thread Starter
Race Director
Joined: Aug 2003
Posts: 11,043
Likes: 3
From: San Jose Pat Tillman - American Hero
I had a situation a couple months back where my Opti started to crap out on me... I got stumbling, then a code, then misfiring, and headed to the shop. I had been smelling a sulfur smell on decelleration (i.e., run car up to 4000RPM, let off gas, and do not depress clutch until ready to stop) for some time, but everybody who I asked about it (including the forum) didn't seem to think it was much to worry about.
When the Opti went, one of my codes was also for a bad O2 sensor. We replaced the Opti, plugs, wires, and the O2, and I was on my way. It's been a couple months now with no new codes, but I would still get an occassional sulfur smell in the car when coming to a stop (at a light, for instance) with the windows down.
All I can come up with is that, during the time my Opti and O2 sensor were failing, but prior to any codes being thrown, my car was dumping too much fuel and it chewed up one or both cats....
When the Opti went, one of my codes was also for a bad O2 sensor. We replaced the Opti, plugs, wires, and the O2, and I was on my way. It's been a couple months now with no new codes, but I would still get an occassional sulfur smell in the car when coming to a stop (at a light, for instance) with the windows down.
All I can come up with is that, during the time my Opti and O2 sensor were failing, but prior to any codes being thrown, my car was dumping too much fuel and it chewed up one or both cats....
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
That could be (raw gas dumping in eventually ruining cats).
There've been some recent threads right here in C4 re Seafoam. Seems to be encouraging and may help. Stress: may. Not many magic elixirs do work, so take it with a grain of salt (or grain alcohol, whichever comes first)/
Sorry to hear the car's acting up.
There've been some recent threads right here in C4 re Seafoam. Seems to be encouraging and may help. Stress: may. Not many magic elixirs do work, so take it with a grain of salt (or grain alcohol, whichever comes first)/
Sorry to hear the car's acting up.
Instructor
Joined: Nov 2005
Posts: 178
Likes: 0
From: Vacaville California
I bought the car from a close friend. I had been storing this car for him in my back yard for about 5 years... Well, I flunked first pass in...
Then I did the complete search here on the site trying to pass also. I did the Seafoam, magic additives, and....Flunk Again... I think I was too far gone for the magic additives to work!
So then I went into real money with new O2 sensors, then the injectors (they did not check out well), and in the end it was replacing the Pre-cats that made the huge difference. PASS!!! (She had about 87,000 miles on her at that point.) It was amazing the numbers difference after the pre-cats were installed.
The car now runs like she should... she ran better each time something was done... even the new spark plugs and wires made a big, noticable difference. She was that neglected.... not now!
Good luck...
Then I did the complete search here on the site trying to pass also. I did the Seafoam, magic additives, and....Flunk Again... I think I was too far gone for the magic additives to work!
So then I went into real money with new O2 sensors, then the injectors (they did not check out well), and in the end it was replacing the Pre-cats that made the huge difference. PASS!!! (She had about 87,000 miles on her at that point.) It was amazing the numbers difference after the pre-cats were installed.
The car now runs like she should... she ran better each time something was done... even the new spark plugs and wires made a big, noticable difference. She was that neglected.... not now!
Good luck...
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Drifting
Joined: Jun 2002
Posts: 1,945
Likes: 41
From: Corinth TX
This may be something that you did but how long did you drive it before taking it in to get it tested? I had a similar problem because I didn't drive the car long enough before testing it. Someone on here gave me that advice and it was a life saver. I think I read stuff on this forum more than I read a newspaper. Most everything you read on here is positive and informative and just the opposite in the newspaper. Goodluck in your problem search. Keep us updated on your fix.
Racer
Joined: Feb 2006
Posts: 462
Likes: 0
From: green valley az
Originally Posted by Perfusion
Went to a shop today to get the '96 tested since it's due in July. The guy didn't care about the LT headers...there was hardly a visual component at all. It was when the 15mph rolling test began that my problems started. I got the following results:
__15mph Test__
HC (ppm) -- Max=52; Avg=9; Measured=13 --> Pass
CO (%) -- Max=0.49; Avg=0.02; Measured=0.01 --> Pass
NO (ppm) -- Max=424; Avg=57; Measured=654 --> FAIL
Sooo.... Looks like I maybe need new cats?
__15mph Test__
HC (ppm) -- Max=52; Avg=9; Measured=13 --> Pass
CO (%) -- Max=0.49; Avg=0.02; Measured=0.01 --> Pass
NO (ppm) -- Max=424; Avg=57; Measured=654 --> FAIL
Sooo.... Looks like I maybe need new cats?
that stated "guaranteed passing emissions",one guy used it and said his passed,so That's all I can tell you
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
NOx which we read in ppm, is a result of high combustion temperatures.
Anything that can cause high combustion temps can cause high NOx numbers.
Defective EGR valves, advanced ignition timming, and carbon deposits can all cause high NOx.
[MODERN CATALYTIC CONVERTORS] can do a good job of controlling NOx but relay on precise air/fuel management.
In your case the convertors are probably shot from a over rich condition.
Anything that can cause high combustion temps can cause high NOx numbers.
Defective EGR valves, advanced ignition timming, and carbon deposits can all cause high NOx.
[MODERN CATALYTIC CONVERTORS] can do a good job of controlling NOx but relay on precise air/fuel management.
In your case the convertors are probably shot from a over rich condition.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
There is a product called "Smog Chek" or something like that. I know people who have used it with great success.
That NOx number really troubles me.
I hate to say it, but the cats may be toast... it might be worth the hassle to replace all the O2s, just to be sure... but if the cats were bad, wouldn't the rear O2s find that to be the case?
I mean, they are there to test the function of the cats. Then again, I don't think they are programmed to check for NOx.
What is the warrantee on OBDII emission controls?
That NOx number really troubles me.
I hate to say it, but the cats may be toast... it might be worth the hassle to replace all the O2s, just to be sure... but if the cats were bad, wouldn't the rear O2s find that to be the case?
I mean, they are there to test the function of the cats. Then again, I don't think they are programmed to check for NOx.
What is the warrantee on OBDII emission controls?
Safety Car
Joined: Sep 2003
Posts: 3,692
Likes: 5
From: Hayward CA
Aaron,
Remember the dyno-day at Apex several years ago. You were running on the lean side then, right? That's probably where your "high combustion" temps are coming from. Give Nick at Newtech Performance a call, and get it tuned with the LT1-edit.
Also, shoot me a PM with the name of the place you got smogged. I have the LT's waiting for installation.
Remember the dyno-day at Apex several years ago. You were running on the lean side then, right? That's probably where your "high combustion" temps are coming from. Give Nick at Newtech Performance a call, and get it tuned with the LT1-edit.
Also, shoot me a PM with the name of the place you got smogged. I have the LT's waiting for installation.
Safety Car
Joined: Jun 2004
Posts: 4,197
Likes: 0
From: lafayette co
Just had the same problem.
Spent $100+ bucks on retests. Took over 9 visits to the smog check place.
I was failing on HC.
Our limit is 1.2. I was consistently pulling 1.21, 1.23, 1.21, 1.22.
So f'king close.
Finally got it passed with a 1.1 after some retuning.
Good Luck!!1
Spent $100+ bucks on retests. Took over 9 visits to the smog check place.
I was failing on HC.
Our limit is 1.2. I was consistently pulling 1.21, 1.23, 1.21, 1.22.
So f'king close.
Finally got it passed with a 1.1 after some retuning.
Good Luck!!1
Drifting
Joined: Jul 2005
Posts: 1,891
Likes: 2
From: Baltimore MD
Originally Posted by Perfusion
I had a situation a couple months back where my Opti started to crap out on me... I got stumbling, then a code, then misfiring, and headed to the shop. I had been smelling a sulfur smell on decelleration (i.e., run car up to 4000RPM, let off gas, and do not depress clutch until ready to stop) for some time, but everybody who I asked about it (including the forum) didn't seem to think it was much to worry about.
When the Opti went, one of my codes was also for a bad O2 sensor. We replaced the Opti, plugs, wires, and the O2, and I was on my way. It's been a couple months now with no new codes, but I would still get an occassional sulfur smell in the car when coming to a stop (at a light, for instance) with the windows down.
All I can come up with is that, during the time my Opti and O2 sensor were failing, but prior to any codes being thrown, my car was dumping too much fuel and it chewed up one or both cats....
When the Opti went, one of my codes was also for a bad O2 sensor. We replaced the Opti, plugs, wires, and the O2, and I was on my way. It's been a couple months now with no new codes, but I would still get an occassional sulfur smell in the car when coming to a stop (at a light, for instance) with the windows down.
All I can come up with is that, during the time my Opti and O2 sensor were failing, but prior to any codes being thrown, my car was dumping too much fuel and it chewed up one or both cats....
Drifting
Joined: Jul 2005
Posts: 1,891
Likes: 2
From: Baltimore MD
Originally Posted by NocarbutaVetteforme
This may be something that you did but how long did you drive it before taking it in to get it tested? I had a similar problem because I didn't drive the car long enough before testing it. Someone on here gave me that advice and it was a life saver. I think I read stuff on this forum more than I read a newspaper. Most everything you read on here is positive and informative and just the opposite in the newspaper. Goodluck in your problem search. Keep us updated on your fix.
DING! DING! DING! Give that man
a Cigar! You have to run the car for about 20 mins to let the cats heat up enough to start doing their thing. Prior to this heat up period you will get false high readings from an emissions test. This is not sitting in your drive way warming up either - take it out on the road.
Drifting
Joined: Jul 2005
Posts: 1,891
Likes: 2
From: Baltimore MD
Originally Posted by bogus
There is a product called "Smog Chek" or something like that. I know people who have used it with great success.
That NOx number really troubles me.
I hate to say it, but the cats may be toast... it might be worth the hassle to replace all the O2s, just to be sure... but if the cats were bad, wouldn't the rear O2s find that to be the case?
I mean, they are there to test the function of the cats. Then again, I don't think they are programmed to check for NOx.
What is the warrantee on OBDII emission controls?
That NOx number really troubles me.
I hate to say it, but the cats may be toast... it might be worth the hassle to replace all the O2s, just to be sure... but if the cats were bad, wouldn't the rear O2s find that to be the case?
I mean, they are there to test the function of the cats. Then again, I don't think they are programmed to check for NOx.
What is the warrantee on OBDII emission controls?
Melting Slicks
Joined: May 2002
Posts: 2,670
Likes: 4
From: Severna Park MD
Originally Posted by IrishJoker
1996 to present = OBD-II, pre 96 = OBD-I
Get this, in MD where I live the 96 cars can have the cats removed, but it they defeat the O2 cat check and have no other codes they pass without even getting the air itself checked. Just plug into the ALDL, wait a few minutes and drive off feeling smug. This really improves the air quality around here. I think I'll run out by the road and sniff some rush hour exhaust because it's so friggin' pure!