[Diy_efi] Making a fake O2

[Adam Wade]

--- David Cooley <n5xmt at bellsouth.net> wrote:

> If your injectors are starting to have reduced flow
> due to deposits, low fuel pressure etc, the stock
> maps are NOT going to be safe.

Most Honda factory turbo motorcycles have never had
their injectors cleaned, and many are operating with
fairly clogged fuel filters.  I've never seen nor
heard of any engine problem on ANY Honda turbo, for
ANY reason.  They run open-loop, and have been in
service since 1982.

If turbocharged motorcycle engines can handle it, I
daresay normally-aspirated applications will be quite
safe when operated in open-loop without BLM, unless
the maps themselves are pretty horrible.

> The O2 sensor is there to correct for changes in
> airflow/fuel flow etc in the engine to keep the A/F
> where the manufacturer specified...

No, the O2 sensor is to command a stoichiometric
mixture during low-load steady-state operation.  One
of the added benefits that has come with that is the
(limited) ability for a manufacturer to partially
compensate for age via the use of BLM tables.  Prior
to the emissions requirements that demanded a
three-way catalyst and long-life emissions components,
there were no oxygen sensors used in fuel injection. 
And if it was really that advantageous, then every
fuel-injected motorcycle made in the past 10 years
would have an O2 sensor.  You'll note that most of
them don't, and the ones that do only did so when the
EMISSIONS requirements were raised to the point where
closed-loop running with a catalyst was necessary.

> If you take a vehicle that isn't brand new, and run
> it in open loop with no corrections, then yes, the
> open loop maps MAY cause damage. 

So all us motorcycle riders who got injected bikes
without O2 sensors can sue the manufacturer for making
self-destructing engines?  Cool!

Frankly, since both open- and closed-loop running
depend on the same ingition tables, any fuel maps that
would "damage" an engine when it was older would also
be very likely to damage it when new.  Further, think
about where best-power fuel mixture is, in terms of
potential engine damage...

Somehow, I am certain that those creating the fuel
maps for automotive OEs are not neary as horribly
stupid as you're saying they are.

| 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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