Date: Mon, 04 Apr 1994 12:53:44 -0500 (EST)
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Bill Layton <WJL@vms.cis.pitt.edu>
Subject: engine surge on idle ,, '85 vanagon
Greetings all!
Let me contribute my tale of woe about engine surges.As a
preface, this is the latest afted spending about 4000$ in 6 months
on repairs.
BEHAVIOR: well, at about 1200 rpm the engine getas stuck in some
sort of feedback loop oscillating vroom-vroom -vroom between
1200 and app. 2000 rpm. it is then nearly impossible for my wife to drive,
bucking wildly in city traffic.
DIAGNOSTICS; everything seems to point to the control unit. first we
replaced the temp sensor [thanks joel!] no luck! if another new sensor
is clipped into the wires and the new one warmed up it still oscillates.
checked oxygen sensors, for air leaks, replaced and cleaned grounding
connectors , checked wiring harness, idle stabilizer...
[is there anything else?]
WITH THE WIRE TO THE TEMP SENSOR DISCONNECTED it does not oscillate.
If the idle is turned down below 12000 it doesnt oscillate at idle
but still does at the magic 1200rpm.oh,-new O2 sensor also.
CONJECTURE;: there is a bad circuit in the EXPENSIVE control unit.
A local vw garage also rechecked everything and suggested the following
which is reasonable given we're not sure , local dealers dont stock '85's
control units ans there's no return for electronics.
They will call as soon as an'85 comes in which runs OK, if swapping the units fixes the oscillations they will immediately order one for my car.
[of course the local junkyards dont have any]
TEMPORARY FIX: You'll love this! they rigged the following up so my
wife can drive the car. Disconnected the connector to the
temp sensor and ran a wire from there to the rear window defroster
switch, defroster on= circuit grounded, defroster off= circuit
broken, one way to start the flip the switch when the oscillations
begin. How's that for an antitheft device!
SOOOOO, does anyone have an extra control unit for an '85 GL they are not using????
Bill
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