Date: Mon, 8 Mar 1999 21:28:33 -0800
Reply-To: David Marshall <vanagon@VOLKSWAGEN.ORG>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Marshall <vanagon@VOLKSWAGEN.ORG>
Subject: Re: CIS Joys! :)
In-Reply-To: <83138a90.36e47445@aol.com>
Content-Type: text/plain; charset="us-ascii"
I have to disagree with a lot of the statements you have Ken. CIS is
simple in operation and troubleshooting. Both failures in your customers
car was caused by neglect and simple failure due to old age. I had a
customer with an 89 Jetta with Digifant-II that wouldn't hold an idle.
Problem: dead frequency valve.
All fuel injection systems will die over time due to wear and tear. If you
were stuck and had some of man's secret weapon - duct tape - you would have
gotten that Rabbit home both times. Duct tape or any other road side fix
would not have helped the Digifant customer.
CIS is plain simple and you can always limp it home. It works on vacuum so
you can't have any leaks. Did you recommend replacing all the rubber in
the intake system? After 20 years almost any rubber is going to get rotten
and break. Heck we change coolant hoses more frequently that every 20
years - right?
If I had to trust my life to a fuel injection system it would be the CIS
system that is in all of my cars.
1978 Rabbit 1.8L CIS
1980 Pickup 2.0L CIS-KS
1985 Cabriolet 1.8L CIS-Lamda
1987 Audi 5000 2.3L CIS-III
1988 Syncro DC 2.0L CIS-KS
Former cars
1987 Audi 4KQ 2.2L CIS-Lamda
1990 Audi 90Q 2.3L Motronic
1991 Jetta 1.8L Digifant II
1988 Syncro DC 2.1L Digifant
I had no problems with the Difant or CIS-Lamda cars, Motronic wasn't bad
when it came to trouble shooting either. The Digifant II system is a
horrible beast - especially if you live in really cold weather or are stuck
in stop and go traffic with really hot weather.
The back fires in your customer's CIS car are most likely caused by a bad
distributor - replace all the vacuum lines and test it to see if it
advances to 40 BTDC when you rev it up. Another problem that will cause
front fire [your case] [especially if you suddenly close the throttle] and
hard starting is a worn out fuel distributor or a faulty warm up regulator.
This is the problem we had with the 78 Rabbit. It is amazing what a new
115mm air flow sensor and Euro GTI fuel distributor will do!
So, is CIS easier to trouble shoot than Digifant, Digifant-II or Motronic?
Yes, vacuum leaks and fuel pressure are the only things you have to worry
about. There are a lot more things that can go wrong on the pulsed
injection systems IMHO.
Don't want to start a flame war here, but there is a reason for Volkswagen
and Audi to hang onto CIS from 1976 to 1999.
At 20:07 08/03/1999 EST, KENWILFY@AOL.COM wrote:
>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
>
>
-- David Marshall - Vanagon List Admin - Quesnel, BC, Canada --
-- 78 VW Rabbit, 80 VW Caddy, 87 Audi 5KSQ, 85 VW Cabriolet --
-- 88 2.0L VW Syncro Double Cab, WANTED: VW / Bombardier Iltis --
-- David's Volkswagen Home Page http://www.volkswagen.org --
-- Fast Forward Autobahn Sport Tuning http://www.fastforward.ca --
-- david@volkswagen.org (pmail) or vanagon@volkswagen.org (list) --