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bavareze Samba Member
Joined: January 03, 2010 Posts: 81 Location: los angeles, ca
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Posted: Wed Dec 09, 2015 11:17 pm Post subject: 84 vanagon emission test failed : high NOx |
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Hi guys
my 84 fuel inj watercooled westy failed emissions due to high nox.
i see no obvious signs of vacuum leaks
all wiring in place, everything looks normal
what is the first candidate for this? catalytic?
thanks for the help!
cheers! _________________ - www.b66ama.com - 29.000 miles in South America - |
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Type17 Samba Member
Joined: April 24, 2012 Posts: 300 Location: Chicagoland
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Posted: Wed Dec 09, 2015 11:29 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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Depends, what did the other readings look like? How old is the cat?
See if you can get a shop to test at the pre-cat port to see if the cat is doing anything before replacing it. |
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bavareze Samba Member
Joined: January 03, 2010 Posts: 81 Location: los angeles, ca
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Posted: Wed Dec 09, 2015 11:46 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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i can have them do that. where is that port located at? _________________ - www.b66ama.com - 29.000 miles in South America - |
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Howesight Samba Member
Joined: July 02, 2008 Posts: 3260 Location: Vancouver, B.C.
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Posted: Thu Dec 10, 2015 3:13 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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High NOx on a 1.9 WBX can be due to several causes, but they all involve overly-high in-cylinder combustion temperatures. I am going to assume that the excess of NOx was not merely marginal and a one-off occasion.
Since the oxygen sensor is a consumable maintenance item, start by replacing it. Then test again. If you still do not pass, but are very close to the line, you can delay replacing your catalytic converter (over $300 for the California version) by trying a couple tricks.
1. Assuming that your HC emissions were significantly below a fail, then try to ensure the vehicle and the engine are just at operating temperature and not any hotter. This is tricky to do. You might have to park near the testing facility to let the van cool down and then proceed.
2. A related trick is to use a slightly colder thermostat. If you go too cold, you will fail on HC's.
3. A very effective technique you can try is to retard your spark timing by about 5 degrees. This reduces in-cylinder temperatures, but also reduces power and gas mileage, so re-set the timing after your emissions test.
4. You can add a temporary water injection system that sprays a very small amount of water into the intake manifold. You have to be really strongly against a new cat for this to be a viable solution. This is really for the Wile E. Coyote in all of us.
5. If none of the above allow a pass, then buy a new catalytic converter. That'll fixya. _________________ '86 Syncro Westy SVX |
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AtlasShrugged Samba Member
Joined: October 30, 2008 Posts: 1605 Location: Decatur, Ga. USA
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Posted: Thu Dec 10, 2015 7:20 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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One problem our old WBX engines have is the standards they were required to meet back in the day were more generous.
When my Vanagon missed the NOX number..it was always very slight.
So the question is. how far off was your NOX numbers?
If yours were close but no cigar..and the engine is tuned correctly..then a new Cat may be the only solution.
Thankfully in Georgia they stop requiring emission testing after 25 years.. |
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bavareze Samba Member
Joined: January 03, 2010 Posts: 81 Location: los angeles, ca
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Posted: Fri Dec 11, 2015 12:35 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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hey, I'm going to adjust a few things, i ordered new fuel lines etc and i will go again to the smog station. the last test was some time ago and i forgot.
thanks all for the help
regarding the timing retarding 5deg: is this supposed to be done by moving 5 deg left or right? _________________ - www.b66ama.com - 29.000 miles in South America - |
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SyncroChrick Samba Member
Joined: January 10, 2005 Posts: 1010 Location: San Francisco, CA
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Posted: Sun Dec 13, 2015 6:38 pm Post subject: Re: 84 vanagon emission test failed : hight NOx |
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My last van failed on slightly too high NoX and then passed just by tweaking the timing a little bit.
Everything else was in good shape. |
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bavareze Samba Member
Joined: January 03, 2010 Posts: 81 Location: los angeles, ca
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Posted: Mon Dec 14, 2015 1:09 am Post subject: Re: 84 vanagon emission test failed : hight NOx |
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SyncroChrick wrote: |
My last van failed on slightly too high NoX and then passed just by tweaking the timing a little bit.
Everything else was in good shape. |
turned it to left or to right? _________________ - www.b66ama.com - 29.000 miles in South America - |
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SyncroChrick Samba Member
Joined: January 10, 2005 Posts: 1010 Location: San Francisco, CA
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Posted: Mon Dec 14, 2015 11:26 am Post subject: Re: 84 vanagon emission test failed : hight NOx |
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bavareze wrote: |
SyncroChrick wrote: |
My last van failed on slightly too high NoX and then passed just by tweaking the timing a little bit.
Everything else was in good shape. |
turned it to left or to right? |
Right I believe but that does not really matter since I don't know where you start from on your van.
I always follow the "3000 rpm" method with a 2" mark - look for it on this forum |
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SyncroChrick Samba Member
Joined: January 10, 2005 Posts: 1010 Location: San Francisco, CA
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Posted: Mon Dec 14, 2015 11:26 am Post subject: Re: 84 vanagon emission test failed : hight NOx |
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bavareze wrote: |
SyncroChrick wrote: |
My last van failed on slightly too high NoX and then passed just by tweaking the timing a little bit.
Everything else was in good shape. |
turned it to left or to right? |
Right I believe but that does not really matter since I don't know where you start from on your van.
I always follow the "3000 rpm" method with a 2" mark - look for it on this forum |
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bavareze Samba Member
Joined: January 03, 2010 Posts: 81 Location: los angeles, ca
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Posted: Wed Jan 06, 2016 7:36 pm Post subject: Re: 84 vanagon emission test failed : high NOx |
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hi!
after trying all tricks I came to conclusion I had to replace the catalytic converter and that's what I did and the van passed the test. Now this is the result and I am wondering whether, apart from being passable, it is actually properly tuned... I am worried that the new cat might get ruined again if something is wrong.
Thanks again for all the help!
_________________ - www.b66ama.com - 29.000 miles in South America - |
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AtlasShrugged Samba Member
Joined: October 30, 2008 Posts: 1605 Location: Decatur, Ga. USA
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Posted: Thu Jan 07, 2016 5:40 am Post subject: Re: 84 vanagon emission test failed : high NOx |
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To check your actual tail-pipe numbers..there is a port ahead of the Cat..and the fuel mixture is checked there with a CO machine. Not a DIY as it requires the test equipment. I don't think that is your problem.
The problem is the tail pipe emission numbers are more strict now. Twenty years ago they were easier to do with a WBX.
With your new Cat..the NOX numbers are borderline now in the 15mph range...in a couple of years your NOX numbers will be higher as the Cat's NOX efficacy declines with use. And..the standards may become even more strict requiring an even lower NOX number than this year.
Some other Vanagon owners would suggest removing your new Cat and installing your old one..and reinstall the new Cat next time you have an emissions test. |
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