[Diy_efi] Emissions Numbers...

[Adam Wade]

--- Mike Frels <mfrels at ix.netcom.com> wrote:

> my scans show 160(lean) at idle/slow and the sniffer
> HCs are low, so to my smog test unexperienced mind
> the results seem to back up the lean condition. 

Agreed.  I just like to use Occam's Razor and cover
all the bases, starting with the simplest ones to
test/eliminate.  "Pruning the decision tree" is
perhaps THE key diagnostic skill, especially where you
have mechanical and electronic components and a
multi-state physical process all going on, ya know? 
;)

So it would appear that for some reason you are lean
at part-throttle cruise and idle, which should both be
closed-loop operation, yes?  Can you confirm that the
vehicle was running on closed-loop mode at both idle
and the 15 mph test condition?  Knowing that would go
a long way toward narrowing the problem; if it's
closed-loop, there are possibilities not found in open
loop, and vice versa.

> Also, my AIR system is functoning 100% and
> completely seals off flow from the exhaust
> manifolds on closed loop. I have verified this more
> than twice.

Okay, that helps.  I was thinking that it was possible
there might be extra oxygen being intentionally
injected into the exhaust from an AIR system, but
that's not the case.  One possibility eliminated.

I think I might work on the spark table to see if I
could smooth out the idle, and see what that does for
you.  I know you can reduce those NOx numbers with
spark timing.  Oh, and are you using a big, funky cam
or something?  The other thing that comes to mind that
could give high residual oxygen readings regardless of
fueling would be a big cam with lots and lots of
overlap.  At low engine speeds, there would probably
be a good bit of unburned mixture passing into the
exhaust.  Of course, then your hydrocarbons should be
higher...  Hm.  This really is a brain-buster.  You'd
already cleaned and flowed the injectors to make sure
they were within spec, right?  Is there a "dead time"
setting in your ECU?  I suppose it is possible that
below a certain fueling level, the injectors are not
opening fully and leaning the mixture more than you
would think from the fuel tables alone.  Please pardon
me if you've covered some of these topics before; my
mind is in a million different places lately.  Feel
free to reply off-list if you think it details would
be extraneous on-list.  :)

> Where can I do more reading on what the smog
> readings indicate?

It takes some poking, but there's some stuff on the
web.  You might want to purchase the full "book" seen
here, which has some practical examples and theory: 
<http://www.smogsite.com/sample.html#egs>

Ooh, and this one is especially good.  Comes from
Toyota. <http://www.autoshop101.com/forms/h56.pdf>

=====
| 82 Honda CX500 Turbo (Cassandra)  90 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |
| M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |

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