Date: Fri, 27 Jul 2012 14:34:37 -0700
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Fuel Injector (or wiring) Question: Deceleration,
Fuel Shutoff Mode
In-Reply-To: <CAB2Rwfj-b+5xehsXNpv87cyfUfszfmw-EHHBwQRXu7XeR+9=9g@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi Neil,
to awnser your injector question ..
in a waterboxer Dififant or Digijet EFI system .
the ECU fires all injectors at once. Sometimes called 'batch fire'.
True ..that makes them not timed to intake valve opening or anything
engine position related.
so if it's cutting off one, it has to be cutting all of them off. it
would be relatively impossible for just one to be shut off.
The way the circuit works..
power from the main relay is present at each injector.
The ecu supplies ground to all of them at once....holding them all open
for however many milliseconds the ECU determines is correct given the
various inputs ....rpm, temperature, and whether throttle is at closed
position, in between, or at WOT.
I suppose an injector could be sticking open or leaking ..
they are normally closed by spring pressure, and it takes grnd supplied
by the ecu to open an injector, or all of them.
I do like the idea of wondering if an injector is faulty , as in worn or
leaking. That makes good sense.
I suppose the ecu could screw up and allow some injector open time
during deceleration ...
but it would do it to all of them as the ECU just sees the injector as
one big four-part injector.
My hunch is 'this path' about the ecu and decel operation being wonky
.........is not it .
scott
www.turbovans.com
On 7/27/2012 1:35 PM, neil n wrote:
> Hi all.
>
> This is for a stock 2.1 WBX, Digifant.
>
> Took my Westy to a shop for the first time in years. Am still tracking
> down a surging issue. Shop owner loaned me an AFM "Vanagon Syndrome"
> harness. This made no difference. Upon return of that part, owner took
> time to demo his Snap On Vantage (graphing meter) on my van. (Throttle
> switch test showed a nice square wave btw). He also kindly gave me a
> brief tutorial on the Vantage. FWIW, this Vantage (4.0) has a
> "Vanagon" section in it.
>
> To test ECU fuel cut off (deceleration mode), he connected the Vantage
> to an injector wire, revved engine to 3K RPM, dropped the throttle.
> Meter graphed brief no voltage to that fuel injector wire, then
> voltage resumed. So that's good. ECU obviously stopped the FI pulse,
> then started it back up at idle. But that was one injector.
>
> In deceleration mode, is there one controller (my term) in ECU that
> turns off fuel to ALL injectors at the same time? Or, is there
> separate controller for each injector?
>
> On the 2.1, do all FI's pulse open at same time? (batch?) or in pairs?
> e.g. 1, 4 3, 2
>
> In other words, was this test of one injector sufficient?
>
> I have to wonder if there's a fault in the wiring or ECU that allows a
> fuel injector to pulse open in deceleration mode.
>
> - residual fuel pressure is OK
> - resistance of each FI tested via ECU plug OK
> - throttle switch closes at idle
> - full tune up was done
> - O2/cat/muffler new
> - engine grounds clean
> - injector spray pattern same on each FI
>
> Neil.
>
> --
> Neil n
>
> 65 kb image Myford Ready For Assembly http://tinyurl.com/64sx4rp
>
> '88 Slate Blue Westy to be named.
>
> '81 VanaJetta 2.0 "Jaco" http://tubaneil.googlepages.com/
>
> Vanagon VAG Gas I4/VR Swap Google Group:
>
> http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
>
| 
