Common mistake, but maybe that might clear things up.
Failed Emissions
Thread Starter
Instructor
Joined: May 2003
Posts: 203
Likes: 0
From: Largo FL
Failed Emissions Vancouver WASHINGTON USA
Failed emissions on the CO side. It's an 85, with an unknown aftermarket exhaust (was there when I got the car). Cat is in place, and I'm thinking it's either the catalytic converter or O2 sensor. Readings were 1.33% at cruise (2000rpm) and pass is 1%. All other readings were well within the passing range. Idle CO was 0.97% vs. 1.2%.
Am I on the right track with the Cat and O2?
If I replace the cat, I think the pipe diameter is 3", is that correct?
Thanks all!
Am I on the right track with the Cat and O2?
If I replace the cat, I think the pipe diameter is 3", is that correct?
Thanks all!
Last edited by Vette Head; Jul 29, 2005 at 08:44 PM.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
No pre-cats on an 85.....if you can't figure this out....contack TJWONG. He has a shop in Vancouver. Good man that can be trusted to do right for you. 
Try doing an "advanced search" for the CO problem...that might turn up several areas to explore.
Try doing an "advanced search" for the CO problem...that might turn up several areas to explore.
Drifting
Joined: Feb 2004
Posts: 1,277
Likes: 1
From: Santa Maria CA
a 12oz. bottle of rubbing alcohol will help in the gas trust me....i know because my friends truck passed impressively after failing! only thing he did was do that and brought it back next week and the 94' 1500 4x4 chevy truck passed with 188,xxx miles 
trust me....i know because my friends truck passed impressively after failing! only thing he did was do that and brought it back next week and the 94' 1500 4x4 chevy truck passed with 188,xxx miles
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Originally Posted by SHINOBI-X
a 12oz. bottle of rubbing alcohol will help in the gas trust me....i know because my friends truck passed impressively after failing!
trust me....i know because my friends truck passed impressively after failing! Corvette Stories
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Drifting
Joined: Aug 2004
Posts: 1,830
Likes: 1
From: atlanta Georgia
make sure you go for a 30 min ride and really ge those cats warmed up before you go and get your emmissions they also sell a thing called guarenteed to pass. Idk about alchol and all that but it def sounds like a sure way to do it if these other guys have done it with good results.
good luck your friend
Sean
good luck your friend
Sean
Burning Brakes
Joined: Apr 2002
Posts: 1,083
Likes: 0
From: Spanish Fork Utah
Originally Posted by redbullapril23
make sure you go for a 30 min ride and really ge those cats warmed up before you go and get your emmissions they also sell a thing called guarenteed to pass. Idk about alchol and all that but it def sounds like a sure way to do it if these other guys have done it with good results.
good luck your friend
Sean
good luck your friend
Sean
My '85 I have to get up to about 230* for it to pass. Heat will do you wonders. Make sure you get it on the freeway for like 10 minutes, and when you take it to the emissions place, leave it running in idle till they are ready for you. Get it nice and hot!!!
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
Failing CO is related to a lack of air entering the engine.
Replace the air filter and clean the throttle body, that should get passing results.
Replace the air filter and clean the throttle body, that should get passing results.
Last edited by GKK; Jul 31, 2005 at 02:22 AM.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Cat on an 85 is 3".
The ends however, are squashed to a oval shape to fit in the 4-bolt flange though. You have to cut back a few inches to get to the round part.
High CO... is not enough air or too much fuel, incomplete combustion.
Raise your base idle a bit, warm the car up, dump some dry gas in there, and it'll squeak by. As for the fix? 02 sensor, maybe new cat. A new air filter will help, but that's not causing it to fail.
The computer should lean out the motor when the EGR opens, if not, it will give a rich condition, since the EGR gases displace oxygen and lowers the stoich.
The ends however, are squashed to a oval shape to fit in the 4-bolt flange though. You have to cut back a few inches to get to the round part.
High CO... is not enough air or too much fuel, incomplete combustion.
Raise your base idle a bit, warm the car up, dump some dry gas in there, and it'll squeak by. As for the fix? 02 sensor, maybe new cat. A new air filter will help, but that's not causing it to fail.
The computer should lean out the motor when the EGR opens, if not, it will give a rich condition, since the EGR gases displace oxygen and lowers the stoich.
Last edited by CentralCoaster; Jul 31, 2005 at 02:24 AM.