Date:         Mon, 5 Aug 2013 14:05:05 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Idle Surge
Comments: To: Bryan Feddish <uprightbassghost@HOTMAIL.COM>
In-Reply-To:  <BLU162-DS11AA3318C6CBD48719E10CE5C0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"; format=flowed

At 01:24 PM 8/5/2013, Bryan Feddish wrote:
>I have that annoying idle surge on my 83.5 WC 
>Westy.  I see allot of information on checking 
>the TPS but they all seem to be for a 86-91. Is 
>there any info on checking and/or adjusting the TPS on an ‘83?

It's in Bentley, Bryan.  You've got two switches 
instead of one, makes it much easier to deal with 
mechanically (electrically the same as the switches are in parallel).

Say more about "that annoying idle surge"?  If 
your closed-throttle switch doesn't open properly 
on a 1.9l the engine will stop running when it 
reaches about ?1500? rpm and not start again 
until it falls to ?1000? rpm (I used to know the 
numbers exactly, but it's been a long 
time).  Done under load on a manual-transmission 
van this produces a violent bucking on initial 
acceleration.  This is the result of the ECU 
thinking the engine is decelerating under load 
(so it shuts off the fuel until idle rpms are reached).

The 2.1l ECU/idle stab control module use the 
closed-throttle switch more actively to control 
idle by means of the idle-control air valve, and 
at the same time are less subject** to the 
violent-bucking syndrome (which in any case 
results from a switch that's stuck closed, not a 
common occurrence).  On my '89 if the idle switch 
is closing properly the engine will idle down and 
hang above 1000 rpm for a second or two, then 
down to a stable 900 or so.  If the switch fails 
to close the idle stays above 1000 and is 
unstable.  But the 1.9l ECU doesn't know or care 
about idle as such, all the idle stabilization is 
taken care of by the little module that advances 
timing when the engine slows below standard idle speed.

** because they changed the thresholds so the ECU 
doesn't go to deceleration mode unless it's 
gotten to a significantly higher rpm first.

Tell us in detail about the symptoms?

Yrs,
d