Date:         Thu, 10 May 2001 18:44:24 -0800
Reply-To:     Mark Keller <kelphoto@islandnet.com>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Mark Keller <kelphoto@islandnet.com>
Subject:      Re: Gas Milage and the Fuel Pressure Regulator
Comments: To: David Beierl <dbeierl@attglobal.net>
Content-Type: text/plain; charset=us-ascii

Listmembers,

I originally Posted

"The first clue that the fuel pressure regulator is setting too high a
pressure is cold mornings when temp I, an air temp sensor, determines if
the computer richness the mixture to start the engine.  A pressure
regulator that is beginning to get too high will cause the engine to
sound like it's running on three cylinders, or chug, and then as it
warms up and the Temp I compensation is removed, the chugging smoothes
out.  I've had this, and was related  too high a fuel pressure."

David Beierl wrote:
>
> Oops, missed that one.  Yes, you're right -- T I + AFM = air mass.  The
> cold compensation is from T II.
>
> david
>
> At 01:57 PM 5/10/2001, Mark Ingalls wrote:
> >Really, Thanks Mark for a good post to hash out.
> >
> >
> >But I was under the impression that the temp 1 was a constant imput to the
> >ECU. It tells the density while the AFM tells the volume. Together they
> >would be mass air flow.
>
> >Mark Ingalls


To add to the discussion regarding Temp I function on the Digifant
system:


The information I received from Darrel Boehler was that that extra fuel
enrichment is added by the ECU when the TEMP I sensor indicates near
freezing air. The ECU's map may then wait until either an indication
from TEMP II, i.e. engine beginning to warm, or just wait until close
loop before the TEMP I enrichment value is canceled out.

  Either way, Darrel "guestimated" the value to be 20% extra to the
regular cold start mixture map. It seems Darrel stated that this is the
only purpose for the TEMP I sensor.

Sincerely,

Mark Keller
91 Carat
Cowichan Bay, BC