Date:         Mon, 8 Mar 1999 20:07:17 EST
Reply-To:     KENWILFY@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         KENWILFY@AOL.COM
Subject:      CIS Joys! :)
Content-type: text/plain; charset=US-ASCII

With all the talk on this list about the 4 cylinder conversion and how simple
and reliable that the CIS injection system, just want to give you folks a wake
up call.  I have worked on VWs with this injection system for several years.
And it is a very basic and rather simple injection system.  However it has its
own quirks that some times make troubleshooting a nightmare.  The thing that
you have to remember with the CIS system (used on Rabbits, early Jettas and
Golfs) is that air pressure in the induction system is critical.  Any air
leaks in the intake will make the vehicle run rough, or possibly keep it from
starting at all.  I have been having just this problem with a customer's car
and it has caused me all kinds of trouble.  First the car decided it didn't
want to start one day after sitting in the parking lot of a local store.  I
went there and tried to troubleshooting the system.  Everything seemed fine
but it still wouldn't start.  Finally I noticed that a tube that attaches to
the bottom of the air boot had come unhooked.  After I plugged it back in the
car ran great again.
After a few months the car started running poorly again.  It would stall at
lights and every time you put it in reverse.  I checked the tube first of all
to see if it was plugged in securely.  It was and so I proceeded to
troubleshoot the rest of the system.  Still nothing.  Then I ran my hand under
the airboot and I figured out what was wrong.  The boot itself had gone rotten
and was broken on the bottom.  The leak wasn't severe enough to prevent the
car from starting (the induction air creates a pressure difference which
raises the air plenum which allows the fuel to flow to the injectors) but it
would make the car stall.  It would also allow the air plenum swing shut
abruptly when you put the car in reverse thereby cutting off the fuel flow to
the injectors (the stalling in reverse was the thing that I couldn't figure
out).
I have also had problems with slight backfires causing the air plenum to stick
shut.  This makes a normally fine running car suddenly not run anymore for no
apparent reason.
What I am trying to say is that any system, no matter how seemingly simple (or
complex) can have its own particular frustrating quirks.
So is the CIS system more simple than the Digijet or Digifant systems in our
vans?
Yes.  But is it easier to troubleshoot?  Not really.
Sorry for the low Vanagon content, just venting a little.
Ken Wilford
Van-Again
John 3:16