Will these mods fail the emssions test?
Thread Starter
Instructor
Joined: Mar 2005
Posts: 157
Likes: 2
From: Fayetteville Ga
Will these mods fail the emssions test?
I've searched around, but couldn't find an answer to this exact question. So here goes. Will any, or which, of the following will fail me on the smog test. Mine car is an 86 L98
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25
I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work. 
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25
I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work.
Advanced
Joined: Jun 2005
Posts: 54
Likes: 0
From: San diego Ca
it all sounds pretty good excpet for maybe the cat i have been told that if the cat doesnt heat up enough it could fail emissions because i had headers on mine and they didnt heat up the cat and i had to go back to stock is what the emissions people told me so im not sure about the precat but everything else seems ok
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
You may need a chip because of the cam or injectors. That could easly be handled by someone who is compintent such as Alvin at www.pcmforless.com The one cat should not cause a problem since you can buy a head pipe that eliminates the 2 pre cats and it is 49 state legal.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Originally Posted by Flyingboy
I've searched around, but couldn't find an answer to this exact question. So here goes. Will any, or which, of the following will fail me on the smog test. Mine car is an 86 L98
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25 I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work.
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25
I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work. I would fail you immedately if you brought it to me for a inspection.. Number and placement of the cats must be factory!!
It really depends on what camshaft you go with. Putting those injectors without tuning in almost guarente you to run to rich to pass.
Thread Starter
Instructor
Joined: Mar 2005
Posts: 157
Likes: 2
From: Fayetteville Ga
Originally Posted by Alvin
I would fail you immedately if you brought it to me for a inspection.. Number and placement of the cats must be factory!!
It really depends on what camshaft you go with. Putting those injectors without tuning in almost guarente you to run to rich to pass.
It really depends on what camshaft you go with. Putting those injectors without tuning in almost guarente you to run to rich to pass.
But aren't the pre-cats an 84-87 item. 88-91 has only one main cat? Or am I wrong? Same L98 engine. How do the later models with one cat pass? I bought the Dynomax replacement front Y pipe with a Magnaflow cat w/ air pipe. Shouldn't the new 3 stage cats do as well as the old school cats?
Most inspection shops are just looking to see if the cat has been removed completely. Besides, if it passes, it passes.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Yes you are right.. it should do well.
but the law is the number nor the location of the cats cannot be changed. thats a federal law. If you came with factory precats you must have precats. I would fail you but htats not to say others wouldn't. Most people are too lazy to look up a item like this.
its a federal law btw..
we would have DMV guys come in with all kinds of wacky crap that was just designed to test you. If you failed to catch it they would fine your station or even worse. for some things they woudl revoke your inspector license and others they would actually take your drivers license!! Thats why I was always really hard on cars that came to me.
but the law is the number nor the location of the cats cannot be changed. thats a federal law. If you came with factory precats you must have precats. I would fail you but htats not to say others wouldn't. Most people are too lazy to look up a item like this.
its a federal law btw..
we would have DMV guys come in with all kinds of wacky crap that was just designed to test you. If you failed to catch it they would fine your station or even worse. for some things they woudl revoke your inspector license and others they would actually take your drivers license!! Thats why I was always really hard on cars that came to me.
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Thread Starter
Instructor
Joined: Mar 2005
Posts: 157
Likes: 2
From: Fayetteville Ga
Originally Posted by Alvin
Yes you are right.. it should do well.
but the law is the number nor the location of the cats cannot be changed. thats a federal law. If you came with factory precats you must have precats. I would fail you but htats not to say others wouldn't. Most people are too lazy to look up a item like this.
its a federal law btw..
we would have DMV guys come in with all kinds of wacky crap that was just designed to test you. If you failed to catch it they would fine your station or even worse. for some things they woudl revoke your inspector license and others they would actually take your drivers license!! Thats why I was always really hard on cars that came to me.
but the law is the number nor the location of the cats cannot be changed. thats a federal law. If you came with factory precats you must have precats. I would fail you but htats not to say others wouldn't. Most people are too lazy to look up a item like this.
its a federal law btw..
we would have DMV guys come in with all kinds of wacky crap that was just designed to test you. If you failed to catch it they would fine your station or even worse. for some things they woudl revoke your inspector license and others they would actually take your drivers license!! Thats why I was always really hard on cars that came to me.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Actually my '88 came with the pre-cats and a main cat but replacing them with a modern hi-flow 3-stage main cat is 48-states legal.
If the head porting is done to maintain swirl and velocity with minimal removal of material the porting should not negatively effect emissions.
The main thing with the cam change is to not go overboard on event overlap. To calc overlap add the advertised int & exh durationis, divide by 4 and subtract the LSA. If this number comes in below say 30deg you should be fine. For example the ZZ-9 cam, with advertised durations of 282/287deg and LSA of 112deg, has an overlap of 30.25deg.
Remember that, though 1.6:1 RRs do not change overlap at advertised durations, they do in fact add 2deg of duration to each valve at .050" of lift.
You may be able to tune your engine with the AFPR since you have a MAF to measure actual air flow. A simple scan of INT & BLM values will tell the story if you need a custom chip.
If the head porting is done to maintain swirl and velocity with minimal removal of material the porting should not negatively effect emissions.
The main thing with the cam change is to not go overboard on event overlap. To calc overlap add the advertised int & exh durationis, divide by 4 and subtract the LSA. If this number comes in below say 30deg you should be fine. For example the ZZ-9 cam, with advertised durations of 282/287deg and LSA of 112deg, has an overlap of 30.25deg.
Remember that, though 1.6:1 RRs do not change overlap at advertised durations, they do in fact add 2deg of duration to each valve at .050" of lift.
You may be able to tune your engine with the AFPR since you have a MAF to measure actual air flow. A simple scan of INT & BLM values will tell the story if you need a custom chip.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
I believe you can remove the 2 precats. IMO the vette is an exception to this rule. Here is a kit to allow it on the L98 cars http://www.ecklers.com/product.asp?p...Q9G6DWVBMC99F6
It may be you need the kit to get the epa cert.
It may be you need the kit to get the epa cert.
Safety Car
Joined: Feb 2001
Posts: 4,397
Likes: 0
From: Looks like I picked the wrong week to stop sniffin glue Orlando
Originally Posted by 93 ragtop
I believe you can remove the 2 precats. IMO the vette is an exception to this rule. Here is a kit to allow it on the L98 cars http://www.ecklers.com/product.asp?p...Q9G6DWVBMC99F6
It may be you need the kit to get the epa cert.
It may be you need the kit to get the epa cert.
Edit: Ultimately, if you can find someone to work with you and allow you to play with fuel pressure and timing while on the emissions dyno you might be able to get it dialed in and running really clean before the actual test
Last edited by IBEAM700; Oct 13, 2005 at 08:18 AM.
Race Director
Joined: Sep 2005
Posts: 13,269
Likes: 0
From: Sharpsburg Georgia
GA Events Coordinator
Originally Posted by Flyingboy
I've searched around, but couldn't find an answer to this exact question. So here goes. Will any, or which, of the following will fail me on the smog test. Mine car is an 86 L98
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25 I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work.
1. 1.6 roller rockers
2. Ported head
3. #24 injectors with AFPR
4. mild cam, one or two notches over stock
5. removed pre-cats, one main Magnaflow cat
6. EGR and AIR systems intact
I thought Georgia only went back 20 years on emissions, but it's 25
I'd love to hear from you California guys on this one. I hear some hot setups and the Ca emssions is stricter than ours here in Ga, but we're gaining. The downtown Atlanta skyline is disappearing during summer, and we commuters are getting confused on the drive into work. 
Burning Brakes
Joined: Nov 2003
Posts: 914
Likes: 1
From: Redding Ca
I would fail you immedately if you brought it to me for a inspection.. Number and placement of the cats must be factory!!
.
California has a 2-part bi annual smog test: The tailpipe test and the visual test. If your smog tester connects the missing pre cats to your year, you are toast. I have a 1988 and it still has pre cats. I think they lasted until around '91, advent of LT1. Many smog stations do not have testers who are familiar with each year Corvette. If they are not looking for missing smog equipment and everything looks GM, you might waltz right through it. But my luck does not work that way
.
California has a 2-part bi annual smog test: The tailpipe test and the visual test. If your smog tester connects the missing pre cats to your year, you are toast. I have a 1988 and it still has pre cats. I think they lasted until around '91, advent of LT1. Many smog stations do not have testers who are familiar with each year Corvette. If they are not looking for missing smog equipment and everything looks GM, you might waltz right through it. But my luck does not work that way
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Your car has 3 cats, 2 precats and one main cat. Thats the way all 86-91 corvettes are from the factory.
I'm from SC, and from what I remember of GA emissions, its not terribly strict in GA. So, you should pass with most of those, but the cam change itself is a more delicate issue. If you do not tune it with a chip change, you likely will not pass the sniffer.
AIR wont affect the sniffer if the engine is hot, and a good properly functioning main cat should cover for the EGR but if you run into higher NOx then thats going to be an issue. Tuning may make a difference there, but you will probably want a chip change to take out Code 32 anyway. You'll also likely require the tune for the injectors and this combination as well, but if you dont change the cam the injectors would not be an issue.
The question is what cam are you putting in it? If you plan on no further major mods or eventually some mods then it makes a difference, you must have a plan before throwing money at it.
I'm from SC, and from what I remember of GA emissions, its not terribly strict in GA. So, you should pass with most of those, but the cam change itself is a more delicate issue. If you do not tune it with a chip change, you likely will not pass the sniffer.
AIR wont affect the sniffer if the engine is hot, and a good properly functioning main cat should cover for the EGR but if you run into higher NOx then thats going to be an issue. Tuning may make a difference there, but you will probably want a chip change to take out Code 32 anyway. You'll also likely require the tune for the injectors and this combination as well, but if you dont change the cam the injectors would not be an issue.
The question is what cam are you putting in it? If you plan on no further major mods or eventually some mods then it makes a difference, you must have a plan before throwing money at it.
Burning Brakes
Joined: Nov 2000
Posts: 1,012
Likes: 1
From: Bowie MD
I am so freaking Glad I passed my third in 4 years strict MD emissions test last friday. We have this rolling dyno/tailpipe sniffer thing. They pressurize your gas tank first . You have to pass the Idle smog test next. Then you have to follow a TV that has you apply gas as if going up a hill climb and then coast going down hills on the rolling dyno. 2 Years ago I failed due to my High flow CAT was burned out by running too rich for two years. Once the Cat was replaced, It passed with flying colors on the Super Ram, larger injectors, ZZ4 Cam and motor with emission pumping into Headers. They put the mirror under the car and saw the CAT and were pleased. With the Borla exhaust, I litterally roar inside the State Run Emmisions building when going up the Virtual Hills. This is in the Capital of Annapolis MD. All the other emmission tech tech come over to see it fail, and act real Damn disappointed when it passes so cleanly.
Burning Brakes
Joined: Jan 2002
Posts: 993
Likes: 4
From: Glen Burnie MD
My early 86 came with only one main cat, no precats. It had the later-style front Y (ie, not 84-85) but with NO precats.
FWIW, I just today passed MD emissions with a similar setup. SuperRam, ported heads, LPE cam, single main cat, stock-like chip (off-the-shelf mass-production chip from previous owner). AIR intact, EGR not functioning.
Passed like a champ this time. Last time there was a problem with the AIR hose and I think that caused it to fail.
Plus, the guy who ran the car on the rollers has an 85 and knew how to drive the darned thing (and was extra careful going over the treadmill). The girl who drove it last time (not being sexist, just stating a fact) kept messing up shifts and lurching the car around.
[RICHR]
FWIW, I just today passed MD emissions with a similar setup. SuperRam, ported heads, LPE cam, single main cat, stock-like chip (off-the-shelf mass-production chip from previous owner). AIR intact, EGR not functioning.
Passed like a champ this time. Last time there was a problem with the AIR hose and I think that caused it to fail.
Plus, the guy who ran the car on the rollers has an 85 and knew how to drive the darned thing (and was extra careful going over the treadmill). The girl who drove it last time (not being sexist, just stating a fact) kept messing up shifts and lurching the car around.
[RICHR]
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Originally Posted by rrubel
My early 86 came with only one main cat, no precats.
Last edited by vader86; Oct 24, 2005 at 10:17 PM.