Date: Thu, 22 Oct 1998 18:09:55 -0500
Reply-To: Darrell Boehler <midwesty@MIDWEST.NET>
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Darrell Boehler <midwesty@MIDWEST.NET>
Subject: Re: Digfiant being defiant
Content-Type: text/plain; charset="iso-8859-1"
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Hi Malcolm,
Excellent advise, it is a must that the rest of the system be in proper
repair and tune before attempting afm( air flow meter) adjustment. I
didn't stress that enough on my original post. Thanks for emphasizing this
Malcolm. It is a rare thing when a digifant afm needs adjustment. The
bosch book "Bosch Fuel Injection & Engine Management " you mention is
especially good to have and review from time to time. It is like icing on
the cake and is relatively easy to understand. With lots of trouble shooting
and component analysis.
Darrell
-----Original Message-----
From: Malcolm Holser <mholser@ADOBE.COM>
To: vanagon@VANAGON.COM <vanagon@VANAGON.COM>
Date: Thursday, October 22, 1998 10:50 AM
Subject: Re: Digfiant being defiant
>> Good luck with your quest. One little word of caution it is necessary
>>that your tune up items be in good shape no bad wires etc. If you have a
>>leaky injector this will not be good either. So please mark the gear so
>>you can return it to the original position.
>>
>
>Do this stuff first, make it all right before you go messing with the AFM.
>
>*Check all the plugs and wires, rotor, distributor cap, timing -- general
>tune-up
>*Check all the FI wiring harness, unplug the wires at each connector and
look
> at the contacts, reconnect, check all the grounds. Be methodical.
>*Check the fuel pressure and the fuel pressure regulator (you need a fuel
>pressure
> gauge for this, but it is a useful tool you should own).
>*Check all five injectors for proper spray pattern and for leaks -- in your
>case
> pay particular attention to the "extra" cold-start injector.
>*Check for intake air leaks
>*Re-check the temperature sensors -- does the car run well cold and only
give
> fits as it warms up?
>*Check the AFM wiper track. These wear out, although the usual symptom is
> intermittent "cutting out" while driving.
>
>While the info on the AFM spring adjustment is valid, this sort of thing
>usually
>is gradual (it can show up suddenly). Check everything in order, and then
you
>might want to start messing with that spring. This is kind of scary work,
as
>the tension here controls the open-loop mode fuel mixture across the whole
>throttle range.
>
>A recommendation is to buy, read, and keep the Probst Bosch fuel injection
>manual
>in addition to the regular Bentley book (Probst is a Bentley book, too, I
>think).
>Most of the list vendors sell it. The FI is not all that difficult to
>service,
>but it is something with many factors controlling it, and you really want
to
>deal with them in a methodical proper order.
>
>Good FI mechanics are out there, but are tough to find sometimes. I advise
>that you become one yourself. The tools (mainly a good VOM, a fuel
pressure
>gauge, and the books) will set you back the cost of a single repair session
>or less.
>
>Malcolm H.
>
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