Date: Mon, 24 Sep 2007 23:28:23 -0700
Reply-To: Michael Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Elliott <camping.elliott@GMAIL.COM>
Subject: Two possibly related symptoms?
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In my search to find out why my 1.9L auto gets Worst Mileage (read
relevant info at http://camping.elliott.googlepages.com/poormileage ) some
improvement MIGHT have been made by replacing the old O2 sensor with one
that shows more lively response; and by torquing the intake runners on the
right side, possibly eliminating an air leak that may have been
responsible for the right side to be running lean and the left to have
been forced rich by the ECU to compensate (since all the ECU knows is the
averaged mixture of all four cylinders). Now the plugs all look the same
and the exhaust pipe temps read the same all 'round.
One 200 mile trip up to 6,000 feet then back to sea level resulted in 16.2
mpg, a 5% improvement in mileage. Hard to be sure with one trip.
Anyways, I'm noticing two misbehaviors. Possibly related?
1. When going down long grades, when I lift my foot off the gas pedal the
O2 sensor pegs in the rich direction. This suggests that gas is being
injected despite the foot off the pedal. From what I read, the idle switch
on the throttle valve is meant to tell the ECU that I am not stepping on
the pedal and it should not be injecting fuel? Following the Bentley
procedure, I tested switch continuity, presence of 5V on the switch,
switch action (it clicks-closes when it supposed to), and Temp 2 response,
and they all check out OK. This MIGHT be a behavior that has been around
since I got the van, I only installed the O2 monitor last week.
2. When the engine is cold, it is gutless. It revs fine in Park or
Neutral, but when in gear it won't rev and can barely move the van. Then
after a few seconds it picks up power and drives fine thereafter. This is
NEW behavior that developed last week after checking compression. New
rotor, distributor cap, plugs were subsequently installed to see if I had
messed something up, but no improvement. Plug wires inspected and seem to
be just fine. Timing, advance and retard all check out fine.
Again, what I know so far, what has been tested, is at
http://camping.elliott.googlepages.com/poormileage
and I could sure use some ideas of other things that might cause these two
exciting symptoms.
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
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