[Diy_efi] Emissions Numbers...

[Adam Wade]

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

> 15mph:
> HC(ppm) std-152 reading-108
> CO(%) std-.86 reading-.37
> CO2(%) 13.3
> O2(%) 2.3
> NOx(ppm) std-1146 reading-1635(*FAIL*)
> Dilution(%) std->6 reading-13.7

That looks frighteningly lean to me.  I know on
motorcycles, at "best power" you generally get
something in the ballpark of less than 1% O2, about
10-11% CO2, under 1000 ppm HC, and 5-7% CO.

The only way to get HC numbers that low, I would
think, would be at or near stoich with a three-way
cat, unless you run drastically lean.  Your other
readings sure look super-lean to me.

> If I remember right high NOx numbers are usually a
> result of high combustion temperatures due to lean
> conditions.

Well, conditions right around stoich, although you can
lower the NOx with spark timing.  I doubt you will be
able to make the numbers without a cat, but if you
can, it'll definitely improve things in the NOx
department to retard the timing, thus lowering peak
pressure, and thus combustion temperature.

> I am thinking that I may have an injector or two on
> the O2 sensor side of the engine that are either
> somewhat clogged or not opening properly at low
> speeds.

I think you probably have it backwards.  If it is in
closed-loop mode, which I am assuming it would be (it
would have to be to use the O2 sensor to adjust
fueling in real-time), then you are probably RICH on
the O2 sensor side, if anything, thus causing the
sensor to lean the mixture.

Have you checked your sensor to make sure that it is
well-grounded, and that there are no spurious signals
on the O2 sensor lead to the ECU?  Is there maybe an
air injection system that wasn't properly disabled?

=====
| 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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