Date:         Thu, 25 Dec 2008 20:55:52 -0600
Reply-To:     Max Wellhouse <dimwittedmoose@CFU.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Max Wellhouse <dimwittedmoose@CFU.NET>
Subject:      Digifant and Fuel Injection Basic questions(long)
Content-Type: text/plain; charset="us-ascii"; format=flowed

Reading through this Haltech ECU aftermarket manual, I'm convinced
this setup was not written for the John Muir type VW mechanic.  I
have some terminology questions perhaps some of our more educated
Vanagon gurus could answer; maybe  not on  Christmas night, but in
the next day or two(I do this stuff when I have the time at the
keyboard you know!)

I should preface these questions by saying in normal weather
conditions, this 2.1 engine does start fairly effortlessly, and runs
okay.  I'm just trying to decide if I have everything set up
optimally, as the Haltech E6S controls both ignition advance and fuel
injector firing

Ignition questions:
1.  Since I've never had the stock Vanagon 2.1 distributor apart, can
anyone tell me if there are centrifugal advance weights inside it
that should be disabled?  I assume that there are no vacuum advance
workings as I see no hoses or additional hardware on the distributor
like the old style Bosch Beetle distributors.
2. Since the 2.1 Digifant apparently has an internal ignition
module(unlike the 1.9), Haltech wants an external one in the engine
compartment, so I grabbed one off a Jetta in a junkyard, complete
with wiring plug and heat sink(remember, this was back in 2001 when
the original installation was done)..  Haltech makes reference to
a"dumb" ignitor and an "intelligent" ignitor, and the difference
seems to be whether the ignition module controls dwell or not. Does
anyone out there know if the Bosch unit is dumb or intelligent?
3. The next confusing term is Trigger Input.  They would like to have
the "rising edge" of the trigger start around 70 degrees before TDC
and the "falling" edge around 10 BTDC or somewhere in that
neighborhood.  My understanding of this is that while the  coil spark
won't necessarily fire at 70 degrees BTDC, this gap between 70 and 10
is where spark is "allowed".  Is this the optimum "window" for the
Vanagon engine, or should I change it to maybe 60 BTDC and TDC?  The
reason I ask these questions is that there are times when I try to
start the Vanagon and it gives off those first few hesitating engine
revolutions that smacks of way too much initial advance in
timing.  IIRC,  I have the Haltech set at 10 degrees of advance at
start and idle, and ramping up to 40 degrees by 2500-3000 rpm.  I
have no pinging(and never have) that I can hear at any load level on the motor.
4. Haltech refers to two ignition output modes in the ECU  one is
called "Constant Duty" and the other is "Constant Charge"  If I were
using the optional Haltech ignition module, they'd have me in the
constant duty mode since it is one of the "intelligent" ignitors
referred to in question #2, but since I'm using a generic Bosch ICM,
I'm guessing that I should be using constant charge.  Anyone know
what the difference is?  It may be the difference between the
dumb/intelligent ignitor in #2.  The other set up quandary I have is
whether to set up the trigger edge on the "rising edge" or the
"falling" edge.  Most Hall effects they want on the rising edge I
think as they want reluctor ignitions on the falling edge.  I'm
assuming I should leave the "duty cycle" to 70% high and 30% low.
5..The last question on the ignition part is something called Rotor
Phasing.  It's entirely possible that the Hall sender's chopper wheel
isn't in sync with the rotor when it passes by a plug wire
terminal.  Not being able to see the chopper wheel may be a problem
in setting this up.  I think what they want is to have the rotor
right in the middle of the 60 degree window of spark
opportunity.  Should I even mess with this?  They warn of not doing
the simple fix by spinning the distributor to align
everything.  Since the Haltech ECU controls the timing, I'm not sure
loosening the clamp on the distributor would change timing in the
first place, but could alter that trigger thingie.

FUEL INJECTION QUESTIONS
1.In Haltech's Basic mode, three types of fuel injection can occur,
Multi-point, Batch fire, and Staged injection.  Since I've never
heard of these three types referred to in any Vanagon conversation,
I'll ask the simple question;  which one describes the Vanagon system
the best?  Multipoint they describe as the most common being defined
by one injector per cylinder and multipoint fires all injectors
together, but that sounds like it's wasting fuel, right?.  They say
Batch fire is for throttle body or non-turbo rotary engines and fires
two banks of injectors alternatively. Staged injection is for high
boost turbo engines so it shouldn't apply as I think you have to have
multiple injectors per cylinder for that to work..

2. If I were to switch to the Advanced mode operation, I can do
something called Sequential Injection which they say allows fuel to
be delivered to the engine at a time when combustion is best.  Since
the Haltech has 4 channels of output, , it can run full sequential
injection for a 4 cylinder engine.  Would this be a plus for the
Vanagon over one of the Basic modes of operation?   It would involved
adding a "home"trigger to the Haltech ECU that I don't currently have
wired, but I'm not sure where this trigger signal would come from.If
this is more hassle than it's worth, then I guess I'll revert to the
Basic setup.
3. Setting up the injector phasing seems to be the big headache ie
figuring out when to have the injector" angles" set for each cylinder

I quote from the manual  INJECTOR PHASING

" The timing or phasing of these injections is set via the Injector
Phasing Map.  This Map sets the angle of the End of Injection, in
degrees BTDC exhaust(not compression), against the engine
speed.  This allows the injection to be completed before the inlet
valve opens.  The Haltech ECU then times the start of injection,
based on the trigger, so that the injection is completed by the
specified engine angle.  If the ECU computes that there is
insufficient time to complete injection before the specified End of
Injection Time, then injection will continue past this time."

Any idea what those "degrees" oughta be?  Experiment?  Or go back to
the basic mode and forget about it.

Thanks for any or all help you can offer and I hope today was a
blessing for you and your family.

DM&FS