Winter gas vs summer gas

[Gerald Pelnar]

----- Original Message -----
From: Ludis Langens <ludis at cruzers.com>

> Has anyone here experienced problems with "winter" gas?  Especially the
> oxygenated, reformulated, winter gas sold in California in (I think)
> November, December, and January?
>
> The previous two winters, the winter gas caused two of my vehicles to
> occasionally ping under mild throttle conditions.  Each year, by the
> time the weather warmed up enough (February) to consider diagnosing the
> pinging, the problem went away.  One vehicle is PFI and the other has a
> computer-carb.  A neighbor reported similar problems with a TBI engine.

Winter gas has a lower vapor pressure, so it vaporizes easier at low temps.
I'm not sure how that affects how it burns, but it may have something to do
with it.

> This winter, I didn't have the pinging.  Instead, the carb vehicle liked
> to stall when the engine was cool.  The engine acted/sounded like it
> went totally pig rich, the rpms dropped, it started rich misfiring, and
> eventually stalled.

That sounds more like summer gas in cooler temps. It's not vaporizing
(puddling in the manifold) and not mixing with the air so not burning. Did
you not have any problems with the PFI car this year?

Gerald Pelnar
McPherson, KS
wd0fyf at mpks.net
http://www.mpks.net/homepage/wd0fyf/


----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org