Date: Mon, 17 Aug 2009 11:36:26 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Not quite a backfire . . .
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The coolant temp should not drop to a very low reading during a long descent
in the summer.
I would be thinking about a thermostat not working correctly if I saw that
on one of my vans.
This is the main thing I wanted to comment on.
re
With no fuel in the cylinders for so long, a
> plug got fouled with oil. Unburned fuel got into the exhaust manifold and
> ignited there, causing the mild explosions we heard.
Yes....backfire like sounds can be from fuel in the exhaust system getting
ignited.
however, by your own logic and indications observed ( 02 meter ) you
believe that the throttle switch shut off all fuel to the injectors,
so how could there be unburned fuel in the exhaust system, if that were true
?
that sure is a special area.
They only just opened McKenzie Pass *now* ?? In August ?
on the Eugene ( west ) side of the pass, about a mile or so from the pass
itself, on the north side of the road, is a delightful small lake with some
campsites around it. Always wanted to camp there once.
There is also in that area, another *really* nice little lake, with free
unrestricted camping, with campsites around the lake.
Scott
turbovans
----- Original Message -----
From: "Rocket J Squirrel" <camping.elliott@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, August 17, 2009 10:10 AM
Subject: Not quite a backfire . . .
> Mrs Squirrel got a hankering to pick some blueberries yesterday, so we
> took a trip over the Cascades Mountains from Bend, Oregon, down towards
> Leaburg (on highway 126) to find some. For the view, we drove over the
> McKenzie Pass-Santiam Pass Scenic Byway (highway 242, the Old McKenzie
> Highway), which has just opened. It's an amazing road, crossing and
> running next to old lava flows -- stop at the top for a cool view
> (http://vulcan.wr.usgs.gov/Volcanoes/Oregon/HighCascades/dee_wright_observatory.html).
>
> After topping the pass, we got stuck behind a line of cars for about 45
> minutes until a flagman let us through -- ODOT was striping the new
> pavement and we had to wait until the paint dried in the cool temps before
> they'd let us down the other side.
>
> Watched a mess of small orange butterflies on the black lava rocks warm up
> their wings in the sun and take short test fluttersby for the duration.
>
> When the flagman eventually released us we drove down the steady, winding,
> hair-pinny downhill cruise of about 20 minutes. Mrs Squirrel rarely
> touched the gas pedal. The auto tranny (84 Vanagon) was in 2nd, the engine
> rpm-ing at about 3,000 so as to save the brakes; the smell of scorched
> brakes from cars ahead of us suffused the morning air.
>
> Mmmm . . . hot brake pads.
>
> I know from previous long descents in cold temps that when there is no
> pressure on the accelerator pedal, a switch on the throttle body tells the
> ECU to shut off fuel, and the only source of heat for the engine is
> friction resulting from being driven by the transmission. As expected, the
> temp gauge dropped to nearly dead cold. The O2 meter showed pure lean
> mixture: air, in other words.
>
> Midway down we hit a flat stretch of road about a half mile long and Mrs
> Squirrel pressed on the gas pedal a bit as the van slowed and said that
> nothing was happening, no engine power. There were a few mild coughs from
> the engine compartment. Not loud enough to be backfires, I don't know what
> those coughs are called, they were new to me.
>
> I suggested she press a bit harder, and the engine sped up, a bit
> reluctantly, and sounded like it was missing on one cylinder.
>
> HERE'S MY GUESS ABOUT THAT: With no fuel in the cylinders for so long, a
> plug got fouled with oil. Unburned fuel got into the exhaust manifold and
> ignited there, causing the mild explosions we heard.
>
> When the road began to drop again, the foot came off the gas again and
> fuel turned off, and the engine continued cold. A bit later we were at the
> junction with the main highway. A left turn. Look left, look right, look
> left again then a press on the accelerator to get up to speed and from
> that moment on, the engine behaved quite normally. Temp rose up to normal
> range and full "power" (if that is the correct term for what a 1.9l
> provides) was available.
>
> So everything appears to be fine.
>
> --
> Mike "Rocket J Squirrel" Elliott
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> Bend, OR
> KG6RCR
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