Vanagon EuroVan
Previous messageNext messagePrevious in topicNext in topicPrevious by same authorNext by same authorPrevious page (October 2007, week 4)Back to main VANAGON pageJoin or leave VANAGON (or change settings)ReplyPost a new messageSearchProportional fontNon-proportional font
Date:         Mon, 22 Oct 2007 11:04:12 -0400
Reply-To:     "Eastman, Cecil @ ELM" <Eastman.C@ATWOODMOBILE.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Eastman, Cecil @ ELM" <Eastman.C@ATWOODMOBILE.COM>
Subject:      Throttle Valve Switch - Lesson Learned
Content-Type: text/plain

For folks who haven't traipsed this path, allow me to guide you a little.

I've been having problems with fuel flow/injection/etc. For starters, the Throttle Valve Switch on my late '85 was dysfunctional on account of it being missing. Some DPO decided they could live without it, I guess. So, without having an example present to use as a model, I had to figure out what in blazes the Bentley was trying to tell me.

Beginning in late '85, the Digijet TVS is one unit that sits under the throttle body, upside down. (Prior to mid-'85, there were two separate units that performed the same functions.) There is a metal spring that works like a telegraph key. When the key is depressed, opens a circuit and tells the ECU to minimize the fuel supply when you take your foot off the gas. You can hear it click when it activates. Without this gizmo, you get the bucking sensation as the engine is alternately starved and fed gas. You get the same problem if the TVS isn't adjusted properly. The keys: the position of the TVS relative to the cam on the under-side of the throttle body, and the shape of the metal key.

Positioning: the TVS must be positioned so that the switch is activated when your foot is off the gas. Technically, it should activate within .002" - .004" from complete throttle close, but I found that to be such a tight tolerance that it didn't make much sense because your foot can't control the gas pedal that closely. To position, loosen the left clamping bolt, then turn the right bolt, which is an off-center cam. Caution: the allen head of the cam on my bus was pretty weak and I managed to easily strip out the hex. The only way I can adjust it now is to fiddle with it manually. Using a multi-meter, the reading should be zero ohms when the throttle is closed. Using your ears, you should hear a click as the switch is engaged when the throttle is completely shut. This brings us to step 2.

Metal Key: I found that my TVS wasn't activating at any setting because the key was set too short. It wasn't even contacting the cam at any position. So I bent the key into a taller shape so that it would depress enough to activate the switch when in contact with the cam. Then I re-positioned the TVS so that the activation came at the right moment, and voila, done deal.

Hope this helps someone.

Cecil '85 Westy Wolfsburg "Der BrotKasten"


Back to: Top of message | Previous page | Main VANAGON page

Please note - During the past 17 years of operation, several gigabytes of Vanagon mail messages have been archived. Searching the entire collection will take up to five minutes to complete. Please be patient!


Return to the archives @ gerry.vanagon.com


The vanagon mailing list archives are copyright (c) 1994-2011, and may not be reproduced without the express written permission of the list administrators. Posting messages to this mailing list grants a license to the mailing list administrators to reproduce the message in a compilation, either printed or electronic. All compilations will be not-for-profit, with any excess proceeds going to the Vanagon mailing list.

Any profits from list compilations go exclusively towards the management and operation of the Vanagon mailing list and vanagon mailing list web site.