Date:         Sun, 12 Sep 2004 17:01:36 -0400
Reply-To:     Paul Holmquist <pholmquist@INFOBLVD.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Paul Holmquist <pholmquist@INFOBLVD.NET>
Organization: Information Boulevard 1-877-INFOBLV
Subject:      Throttle switch testing
Content-type: text/plain; charset="US-ASCII"

Thanks for the responses to my question about peculiar bucking a few weeks
ago, most pointing to the throttle control switch.  I finally got a hold of
a multimeter and some free time and checked the switch according to Bentley.
The switching points were close to OK, the gap just before idle starting a
little larger than specified by Bentley (.0045 in vs .004).  Is this a
significant discrepancy?  I don't want to fiddle with the switch if it's not
necessary.

A question about testing the voltage at the switch.  The Bentley says to
disconnect the control unit (is this also known as the ECU?) before
connecting a test light at the switch connector.  Does this go for a
multimeter as well?  (I'm relatively new to electronics).  Bentley says that
if there's no voltage and the wires are good, then the control unit is bad.
But how you can tell if the control unit is bad when it's not connected
during the test?

Thanks in advance for any help.

Paul Holmquist
Alfred, NY

86 Weekender

on 8/26/04 7:20 AM, Mary Creasy at mkc1@localnet.com wrote:

> Paul,
> Check the throttle positioning switch, the microswitch under the
> throttle body.  It should be on at idle and full open throttle.  My '85 was
> doing the same thing and adjusting that took it away.
> Dave
> 78 Westy
> 85 Westy
> 93 EVMV 5 sp.
> ----- Original Message -----
> From: "Paul Holmquist" <pholmquist@INFOBLVD.NET>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Wednesday, August 25, 2004 11:58 PM
> Subject: Not typical bucking
>
>
>> If anyone has any insight into the following it would be much appreciated.
>> I've spent some time going through the archives and I haven't found a
> match
>> yet.  I'm experiencing a strange 'skipping', 'hiccupping', gentle
> 'bucking'
>> or 'hopping', but not in the sense I found in the archives.
>>
>> It doesn't happen when accelerating. It's when I'm either coasting along
> in
>> 4th or 3rd with just enough gas to keep constant speed (slight bucking),
> or
>> when down shifting into 3rd or 2nd at a higher rpm and letting the
>> transmission slow the van down (stronger bucking).  It doesn't happen when
>> revving the engine in neutral.
>>
>> The idle seems fine, though I might be imagining a very very slight
>> roughness.  The engine doesn't stall, has no trouble starting.  The van
> has
>> full power and acceleration.  When the bucking happens, it's persistent.
> It
>> doesn't happen for a while and then go away, or stop when I turn the
>> ignition off and then on again.
>>
>> I first noticed it about a month ago, but it was very slight then, almost
>> imperceptible.  It's gotten progressively stronger.
>>
>> I recently had new wires, cap, rotor, plugs, and fuel filter put in.  I
> have
>> a bottle of injector cleaner I'm about to put in the tank (unless someone
>> says not to).
>>
>> Is this fuel, electrical, vacuum, transmission?  Any help is appreciated.
>>
>> Thanks in advance.
>>
>> Paul Holmquist
>> Alfred, NY
>> 86 Weekender
>>
>
>