Date: Thu, 7 Feb 2008 14:54:39 -0800
Reply-To: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Shazam <scottdaniel@TURBOVANS.COM>
Subject: Re: SMOG TEST failure
In-Reply-To: <47AB86A5.807@ucsb.edu>
Content-Type: text/plain; charset="us-ascii"
How is your oxygen sensor ?
Do you know how to take a reading on it to tell if it's got a decent output
?
Is it running warmly enough ?
Like needs to be 180 at least, and warmer than that is better. *always*
leave it idling prior to a smog test, you want it as warm as you can get it.
Rather than think 'parts' ...........think 'adjustments and inspection for
worn parts."
You should check the throttle switch immediately, and adjust if it's off.
They get off and no one ever checks or adjusts them on the vanagons I see.
Also AFM mixture adjustment .......'might' need some attention there, but
that's not something you usually go messing with.
Are the spark plugs at least pretty decent ?
And how's the cat ?
Oh timing too. Timing too advanced can result in out of spec readings, or
too retarded too. But too advanced is the common one.
It is fairly straight forward if you start with the basics and work up.
First check compression.
Then inspect all tune up parts and test oxygen sensor signal.
Then do all the adjustments I mentioned.
And change the oil.
And really check the exhaust system, like your cat.
I just can't say how important checking the basics are and building up from
there.
People will throw parts at an engine when it's got seriously bad compression
on one cylinder, or a hollowed out cat, for example.
You start with the basics, make sure they are ok and logically work your way
up through all the checks and adjustments. It is pretty straight forward
if you take that approach and have just a few pieces of test equipment.
Give you an example of a California waterboxer I had that failed smog. It
would also backfire sometimes or something. There's an injector spray
pattern test in Bentley. I did that test, and a leaking injector was
immediately apparent. ( hence the backfire sometimes at idle ) .
Popped in a good used injector, passed just fine.
Need to just check through all the basics, tests, and adjustments in a
logical and somewhat methodical order............and usually you find about
5 things about half-off.
Scott
www.turbovans.com
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
John Goubeaux
Sent: Thursday, February 07, 2008 2:31 PM
To: vanagon@GERRY.VANAGON.COM
Subject: SMOG TEST failure
My 90 failed the California smog test today. In short, the idle values
were off with HC ppm at 424 where max allowed is 120 though the 2500rpm
values passed fine and are way below limits.
So I am looking for some clues on where to start with this, and while I
realize it might not be straight fwd, thought I would see if anyone has
some insights. Replacing components one by one might get expensive so i
was hoping on narrowing it down on what it **could be.
Idle is fine though it has been rough for a while at startup and I have
had intermittent, what appears like missing at high speeds when
accelerating. I had thought that i was seeing what folks refer to as
the "vanagon syndrome" but with with the idle values like these am
thinking that it could be as a result of the idle control valve (though
it vibrates), the idle control unit or the coolant temp sensor (which i
am told can cause a rich mixture.
It looks like Bentley has clear steps to trbl shoot the idle though I am
not sure, without the proper tools, if I can make the needed adjustments
it calls for.
Thanks in advance for any wisdom that can be shared..!!
-john