Date:         Mon, 18 Sep 2000 08:46:42 EDT
Reply-To:     Wolfvan88@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Lilley <Wolfvan88@AOL.COM>
Subject:      Tinkering with the Digifant Fuel Injection to make it better...
Content-Type: text/plain; charset="US-ASCII"

Do not do it....

The DF FI system is set to read micro voltages and changing a setting might
put it beyond the range for the sensor and the Digifant ignores the reading
and applies a default programed based on the other sensors.
This can seem to increase power, but sometimes it can mask a failed component.

...You are starting to lose a little power in the engine, so you adjust the
timing/air flow meter/ turn the idle adjustment up, etc... to try to regain
power, this might or might or might not work, if it does, it can mask a
failing part: Distributor cap and rotor, plugs, wires, O2 sensor, temp II
sensor, air flow meter, ECU, weak coil, idle control module, fuel pressure
regulator, etc...

What I have discovered with all my tinkering (I had to change my Carb
thinking to FI thinking) is that if all the parts are working correctly, the
DF system runs good.  Throw in a bad component and it can go down hill
quickly.

As discussed in the past posts, the main problems now with the DJ and DF
systems are AGE and MILEAGE.  Parts are simply worn out or have failed.

The FI system is interdependent is good for making up for a failed or out of
spec part, but comes to a point when it will fail.  Fixing one bad part might
work, but sometimes it is more than one part that had failed, so other parts
that are slightly out of spec can cause the NEW part to APPEAR to not work.


In preparation for the Digifant upgrade chip [I want the FI to be setup as
stock, with no artificial setting (Non-stock)], I have put the new air flow
meter back to the original setting (I moved it back the one notch I loosened
it) that it had when I bought it a year ago.  The bottom end response
improved and the overall power picked up a bit.  The point is that a SMALL
change in the spring tension of the air flow meter made a change to the
engine at lower RPMs but did not diminish the upper RPMs, it actually
improved it.  The correct air was flowing for the correct fuel.

I had changed the AFM one notch, earlier when my splice in O2 sensor did not
work correctly because it seemed to made it run better. (It changed the
micro-voltage the ECU received and made my engine run lean with no power,
changing it with an OEM NO splice restored power and resulted in a better
running engine.)  I even loosened the AFM four notches to see the effect, I
lost the bottom end big time.  Coming off from a stand still, with the
throttle was pressed half way and the engine had no power until the revs
moved past 3000 RPMs. (This is what was happening to the engine when I first
bought the van, flat acceleration until past 3000 RPMs, them power)

If you are having low speed problems look at the air flow meter, the wiper
board is worm out in the first part of the wiper board.  Get a new AFM, the
cost is cheap compared to a few years ago.  Now you can just about replace
the entire FI system with after market vendors (LIST VENDERS) (which I have
done) cheaper than buying one or two parts from the dealer a few years ago.



Maybe the list vendors can develop a Digijet or a Digifant parts kit like the
hoses...


Robert