Date: Sun, 24 Sep 2017 14:39:25 +0000
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Emissions Test Failure
In-Reply-To: <MWHPR12MB16296D2BC534F065ED3761B5BA670@MWHPR12MB1629.namprd12.prod.outlook.com>
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When asking for assistance with emissions problems it is helpful to also provide the other test numbers and also the type of test involved. There are idle only tests, test at some other RPM such as 2,500 rpm, and then there are also the loaded tests (dynamometer), which are used to also test for NOx emissions. NOx is the biggie as we all became aware with the Diesel thing. Drive by you may not know emissions test is coming.
I have posted many responses in the past and they should be in the archives. To get to the bottom line. Your failure justifies emissions testing programs. You are a gross polluter even at the 220 ppm limit. Running properly HC (fuel that was never burned) should be well below 100 ppm even before the catalyst. Generally a healthy engine tuned properly can even get below 50 ppm. With a healthy catalyst and the engine running as it should CO and HC emissions should be near 0. Pre-Cat should see CO under 1%. Keep in mind that the O2 sensors function is not just to maintain an ideal mixture, it does much more. In order for the three way catalyst to control HC, CO and NOx both oxygen rich (lean) and oxygen deficient (rich) reactions are required. The O2 sensor continuously switches between rich and lean in order for these reactions to happen concurrently.
Sometimes a catalyst will be lazy and need some time-heat to fire up. When we had old style emissions testing here after a fail, the next step would be to run the engine at 2,500 to "light up" the catalyst.
There are number of things that can cause excess HC including incorrect base settings. Over advanced ignition timing is a common one. A lean cylinder miss fire is the next one in water boxer land. Next comes diluted oil or overfilled crankcase or even the wrong. Then you have to look at engine problems such as valves, (including intakes), and piston-ring problems.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of David Boan
Sent: Friday, September 22, 2017 5:47 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Emissions Test Failure
I recently moved to Idaho and had to get an emissions test for my '85 Westy, which I did today. It failed one part of the test - the HC (PPM) at idle were 350 (the standard is 220).
I spoke with my mechanic who said it was possible that the catalytic converter was not warmed up enough (I had only driven the van down the street a few miles before the test). He suggested driving for awhile and test again.
Has anyone run into this? Does that advice sound right?
Thanks
David
Boise ID
