Don't forget the airflow bypass adjustment in the AFM body. There is a
vertical hole just past the flap housing. Inside it is a screw. It affects
mixture throughout the range. If anyone knows where to find instructions on
this adjustment, I'd like to know. (I've already messed mine up)
Best regards,
Alan Lambert
--- En date de : Ven 11.2.11, Eric J Russell <[email protected]> a icrit :
De: Eric J Russell <[email protected]>
Objet: Re: [alfa] Marginally High CO Emission from L-Jet Spider
@: [email protected]
Date: Vendredi 11 fivrier 2011, 2h51
~ my comments interspaced below ~
----- Original Message ----- From: "alfa-digest"
> From: Robert Lorenzini
> The temp sensor also affects rich/lean. Raising the resistance = richer.
For sure double check the thermostat/temp sensors. Don't trust the dash gauge.
A cheap non-contact thermometer is a fun tool to own.
> IF you wanted, you could pull the fuel rail and injectors free of the
> inlet ports and activate the fuel pump, then check directly whether the
> injectors are leaky when closed. Just a thought.
> From: Charles Slayman
>
> I like your idea of pulling the injector rail and looking for leaks with
the
>
system energized! That fits my criteria of simple/inexpensive tests.
>
> Thanks,
> Charlie
An easier (but less exacting) check is to remove the spark plugs & turn the
engine until you can see the intake valve open (peeking in via the spark plug
hole). Then cycle the key on-off-on-off to pressurize the fuel rail (or 'hot
wire' the fuel pumps) while looking/sniffing for evidence of raw fuel from
that cylinder. It might reveal a badly leaking injector but would not be able
to prove if they were leaking just a little bit.
I suspect a slightly leaking fuel injector would not affect the higher speed
emissions results as much as it would affect idle emissions.
If you suspect the spring tension of the AFM is too weak - leading to an
over-rich condition - you can remove the cover over the AFM (it was glued on
at the factory but can be carefully removed by cutting through the glue) and
watch the arm inside that is
connected to the flap. With the engine running
at a steady speed/load the flap should be quite steady. If the spring tension
is weak the flap will tend to oscilate in the air flow. It was common 'back in
the day' to loosen that spring in an attempt to richen the mixture for more
performance. (It rarely helped and usually just made things worse.) If you
decide to 'adjust' the spring tension, the goal is just enough tension to make
the flap ride 'steady in the wind'.
Where are you located? It might be easier to borrow a known good AFM for
testing (before fiddling with yours). I have a spare if you'd like to borrow
it.
Eric Russell
Mebane, NC
http://home.mebtel.net/~ejrussell --
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