On Saturday, September 19, 2015 at 5:30:51 AM UTC-4, Steve W. wrote:
Ewald Böhm wrote:
On Fri, 18 Sep 2015 22:45:53 -0400, Ed Pawlowski wrote:

I assume the car's computer
knows an instrument is plugged in so it changes the program.

Very few states use OBD emissions testing, and certainly California
doesn't yet, where California is fining VW along with the EPA.

http://www.arb.ca.gov/msprog/smogche...bd_only_im.pdf

Most use tailpipe testing.

Some, like California, run the car through the Federal Test Procedure
on a dynomometer.

Given thats at least three different procedures (where each state can
easily be different), I don't see *how* the engine computer *knows* it's
being tested for emissions.

Since almost no states use the OBD method, that's why I asked how the car
knows it is being tested.


How do you figure that "almost no states use OBD" testing. In fact most
of the states do not use a dyno any longer.

Alaska, Arizona, California (in areas that require "enhanced" emissions
testing), Colorado, Connecticut, Georgia, Illinois, Indiana, Kentucky,
Maine, Massachusetts, Missouri (St. Louis), Nevada, New Hampshire, North
Carolina, Oregon, Texas (Houston and Dallas/Ft. Worth), Utah (Salt Lake
City), Vermont, Washington and Wisconsin, New Jersey, New York (in areas
that require emissions testing), Pennsylvania (Pittsburgh and
Philadelphia) and Virginia ALL use some type of OBD II testing, some use
both OBD II and tailpipe.


I guess that's the list. I know for sure here in NJ they use OBD
for emissions compliance testing. Back in the days of Christie Whitman,
we spent several hundred million dollars installing dynos and tailpipe
testing eqpt in all the state owned inspection facilities. They
gave the contract to some out of state hacks that screwed it up
royally, it took years longer to get working, etc. At the time,
most of us thought it was stupid and that Whitman should have stood
up to the feds, who shoved it down our throats, fought against it, etc.
After it was working, within just a few years, the EPA switched to
using OBD. Of course they had to have know this was coming, it
just didn't pop up overnight. So, just a few years after the dynos
and all the gear went in, they ripped it all out and junked it.

Today, we finally have some sanity. NJ used to check for everything,
from horn, to front end, to headlight aiming. Now they just check
for emissions, they don't even check for cracked windshields or brakes
anymore. The inspection is good for 2 years. New cars don't have to
be inspected for 5 years. Two of my vehicles, an older Mercedes diesel
and my Harley no longer have to be inspected at all, ever again. Yipeee!