TheSamba.com :: View topic - Digifant II wiring questions (1.8 inline 4)

Sat May 03, 2014 7:08 pm

Hi Everyone,

My Vanagon that threw a rod through both sides of the block last week has a new lease on life thanks to Dan in Syracuse and the 1.8 he just removed from his van!

I picked up the engine last night along with the wiring harness, associated hardware and a gas tank Dan generously donated to my project. I'm hoping to have the engine installed and working by tomorrow night!

So far I have the engine thoroughly cleaned, bolted to the transmission and on the mount bars, I'm beginning to dive into the Digifant system and have a few things I need clarification on.

Pin 1 is red/green and is "starter power" where does this connect? Top of the starter solenoid?
Pin 3 is red/yellow and is "fuel pump" where does this connect? Looking at a Jetta wiring diagram it appears it goes to a relay that switches the fuel pump.

I'm also not completely sure how to wire the coil. I know red/black and black both come from the hall ignition control unit but where do the other red/black and black come from?

Apologies in advance for the stupid sounding questions! I cut my teeth on diesel engines and these gas engines are still somewhat "magic" to me.

-Thanks,

Erik

Sat May 03, 2014 8:10 pm

Did this van have a WBX originally? If so, I'd use the appropriate year WBX wiring diagram in the Bentley as your guide for how to wire up the fuel pump, ECU power and coil.

Sat May 03, 2014 8:23 pm

Zeitgeist 13 wrote: Did this van have a WBX originally? If so, I'd use the appropriate year WBX wiring diagram in the Bentley as your guide for how to wire up the fuel pump, ECU power and coil.

No, this was a diesel van. I remember Dan saying something about using the injection pump solenoid wire, I believe for power "starter power" and the fuel pump through a relay. I just can't remember exactly how he explained it. Hopefully he'll chime in soon!

-Erik

Sat May 03, 2014 8:45 pm

I'm sure Dan would know but....

Searching Digifant II in google images gets hits for different diagrams. Which version Digifant II ? Or, what year is ECU, harness etc. from?

On your diesel, the wire to fuel cut off solenoid is from 15 buss which is "ign. on" (engine running) position of a gas powered Vanagon.

Sounds like Dan kindly labelled the wires. ECU 1, if labelled starter power, is likely connected to the 50 buss (starter cranking position of ign. switch) which should be the solenoid connection of starter. This temporarily supplies ECU with power so it can energize the fuel pump while cranking engine. It may also richen up the mix. IDK for sure.

I can't say for sure, but it really sounds like ECU 3 connects to negative side of fuel pump relay. Typically this is relay pin 85. BUT... I see a diagram online that shows a different arrangement.

Sat May 03, 2014 9:37 pm

sorry to find this so late tonight. was working in the yard and garage all day/night

you'll want to use your original diesel fuel solenoid wire as your new Ignition trigger wire.

this would connect to a bosch style fog lamp relay as the ignition trigger
it's a "load reduction relay" so the key wire doens't have to feed all of the amps for the igntion system.
here's a generic image.
except that 85 is the wire from your key for your old fuel solenoid (ignition trigger)
86 is still connected to ground
30 is a fused +12v power feed from the battery (new wire to run) you can reuse your old diesel fuse, but they're kinda iffy as they age..
87 is the new powered (Ignition) wire that will connect to the (15) side of the ignition coil, and the fuel pump(s) and ECU and injectors.
I only used 1 relay in my install, VW uses a fuel pump relay and a injectors relay

Please feel free to call me if you have any questions.. I sent my cell# in the pm sent on friday I think.

for reference here's the Digifant jetta pin out
http://www.a2resource.com/electrical/management/digifant2.html

Sun May 04, 2014 9:47 am

danfromsyr wrote: sorry to find this so late tonight. was working in the yard and garage all day/night

you'll want to use your original diesel fuel solenoid wire as your new Ignition trigger wire.

this would connect to a bosch style fog lamp relay as the ignition trigger
it's a "load reduction relay" so the key wire doens't have to feed all of the amps for the igntion system.
here's a generic image.
except that 85 is the wire from your key for your old fuel solenoid (ignition trigger)
86 is still connected to ground
30 is a fused +12v power feed from the battery (new wire to run) you can reuse your old diesel fuse, but they're kinda iffy as they age..
87 is the new powered (Ignition) wire that will connect to the (15) side of the ignition coil, and the fuel pump(s) and ECU and injectors.
I only used 1 relay in my install, VW uses a fuel pump relay and a injectors relay

Please feel free to call me if you have any questions.. I sent my cell# in the pm sent on friday I think.

for reference here's the Digifant jetta pin out
http://www.a2resource.com/electrical/management/digifant2.html

Hi Dan,

Thanks for the reply.

I think I'm getting close!

I'm going through the harness, replacing some connectors and cleaning it up. So it sounds like I need +12v to the ECU (black/yellow), fuel pump, (15) side of coil, and injectors (brown/yellow). I'll run it all through one relay to keep it simple.

I was getting confused looking at a Jetta wiring diagram, is saw the relays for the fuel pump and injectors and wasn't clear if these were relays inside the ECU or external. I think I've got it now.

Only thing I'm unsure of now is the fuel pump wire from the ECU (red yellow). Where does this connect to the fuel pump if the pump is fed through an external relay. Is it the pump ground?

I'll definitely give you a call if I can't dig up an answer...

-Erik[/b]

Sun May 04, 2014 10:20 am

Once the engine is running, the ECU typically supplies ("switches on") a ground to energize the fuel pump relay so the switch inside it closes allowing it to carry B+ to the fuel pump. In this way, the relay not only handles a higher Amp load, it also switches off the fuel pump when engine stops (safety feature. eg. if engine stalls but ign. still live).

Fuel pump negative ( - ) wire goes to frame, positive wire to 87 of fuel pump relay.

Can you post an image of wiring diagram you're using?

Neil.

Sun May 04, 2014 12:17 pm

Vanagon Nut wrote: Once the engine is running, the ECU typically supplies ("switches on") a ground to energize the fuel pump relay so the switch inside it closes allowing it to carry B+ to the fuel pump. In this way, the relay not only handles a higher Amp load, it also switches off the fuel pump when engine stops (safety feature. eg. if engine stalls but ign. still live).

Fuel pump negative ( - ) wire goes to frame, positive wire to 87 of fuel pump relay.

Can you post an image of wiring diagram you're using?

Neil.

I'd have to look for the diagram I was using, I'll see if I can find it.

I spoke with Dan earlier this afternoon and he was very helpful with my wiring questions. I changed a few connections and the engine fired right up! It only ran for a second and then died, if I hold my finger over the vacuum line that will be connected to the brake booster the engine settled into an idle, idled for 2-3 seconds and then died.

I'm not sure what's wrong, but I'm confident the engine itself is solid so I'm moving on to notching the frame to fit the engine and then to bolting it up. Hopefully in a few hours I'll have the engine mounted and be back asking wiring/engine questions.

-Thanks everyone,

Erik

Sun May 04, 2014 3:48 pm

Hi Eric.

Nice that you've got the engine firing up.

Dan and/or Eric: if you feel I shouldn't be in this thread, please let me know. Though Eric posted to the forum, I may be slowing things down?

Eric: Once engine runs, put your hand on the fuel pump relay. Do you feel it click when engine stops? A cardboard tube or mechanics stethoscope may allow you to hear if this is happening.

I wish I had a Bentley handy to view diagrams, but searching "Digifant II" in google image search, the diagram below shows 1 buss (from coil) connecting to one side of the relay switch coil. ECU 3 goes to that relay socket but does not appear to be connected to relay.

Can you supply the part number off the ECU?

link to image of diagram:

https://sites.google.com/site/rubjonny//images/golf/g2pbecu-pre90.jpg

Neil.

Sun May 04, 2014 5:42 pm

Hi Everyone,

The engine is in the van.

It took a little longer than I had hoped so I'll be putting off the final wiring for tomorrow night.

Neil,

I'm glad you're posting in this thread! I've been on the phone with Dan trying to figure little things out but I appreciate having a "second set of eyes."

When I was test running the engine earlier I was working outside of the van so it was a mess of test leads, jumper cables, and a big red "go button." I did not have any relays installed and had the fuel pump wired directly to power.

Now that the engine is in the van I need to get it wired up all kosher. I'm working with Dan to understand how he had it wired previously (all through one relay).

-Thanks everyone,

Erik

Mon May 05, 2014 8:04 am

Hi Everyone,

I won't be doing the wiring/final assembly until late this afternoon but would like to gather some opinions on mounting locations for various components.

I need to mount the ECU, coil, high pressure fuel pump, and finagle the air intake.

Has anyone out there done this or a similar conversion on a former diesel van? Has anyone tied the air intake into the former diesel intake?

-Thanks,

Erik

Mon May 05, 2014 8:36 am

I am going through a similar conversion, but on a WBX powered van. I mounted the coil and ignition module underneath the coil in the RF of the firewall. This would be the area where your diesel fuel filter would be, but maybe a little more to the left. This way made the most sense and I could use VW plug wires including the coil wire.

The pump is designed to be gravity fed. VW mounted the pump to the frame rail between the tank and the engine. The fuel filter is mounted inline after the pump. You may run into a problem with the pump and the tank outlet. They may be different diameters. I don't recall, but there are inline filters out there that have different hose end sizes you can use as an adapter if needed.

I have not sorted the intake. I am using a factory intake elbow and it puts the Air Flow sensor where the overflow tank should be. You need an air filter, and I imagine you have an Air Flow sensor or Mass air flow sensor, It might get tight trying to connect it to the snorkel in the intake. As long as the air intake ends up in either pillar that is probably adequate.

Mon May 05, 2014 9:07 am

I would echo installing the air intake snorkel if possible. At the very least your air filter won't get clogged as quickly.

The diesel fuel tank likely has the smaller diameter outlet as the air cooled and earlier Vanagons have. I have this type of tank (van was air cooled). I ran without a pre pump filter but due to another issue, crap got in my tank which then clogged pump inlet screen which exacerbated pump noise. I had assumed noise was due to tank outlet size and pre pump filter. In part, it may have been. But. Cleaned pump screen, re-installed square pre pump filter, much less pump noise now though I have yet to run van on hot days. (noise gets worse on hotter days) I also run a post pump filter

Ignore pre pump filter delete images:

https://picasaweb.google.com/musomuso/FuelFilterUpgrade

Most just cable strap the filter to body. IIRC, van-cafe.com sells a kit for this.

Neil.

Mon May 05, 2014 10:21 am

Erik,
I forgot to send you off with some fuel injection hose
make sure you use SAE30R9 5/16" fuel injection rated hose from the fuel pump to the injector fuel rail with FUEL INJECTION HOSE CLAMPS they are a complete band style not a worm gear and are available at any autoparts store.
remember that the lower hose on the fuel rail is the exit, it can be low pressure fuel hose SAE30R7 5/16" to the tank return line.

and a reminder fwiw that inmy install I placed the low pressure "supply" pump by the fuel tank, retained the Diesel filter but changed it to a napa fuel/water separator (marine use I think) and mounted the high pressure pump to the firewall in the engine compartment. again use SAE30R9 FI hose after the pump.

I know my single (1) relay wasn't oem but was 'sufficient'
essentially you can run the engine management w/o a relay, like on the bench or for testing. the relay is a load reduction relay to keep the amperage away from the Ignition key switch. in my instance the fuel pump ran 100% with Ign.

the oem uses a fuel pump relay that is tripped to ground by the ECU to wire a Digifant-II fuel pump relay here's an image I found and modified that may help. *Note that the ECU will trigger this relay for a brief moment to prime the system and won't re-energize the pump till it sees RPMs from the IGN module or HALL sensor. (this is a reason I didn't install this function/safety feature). the safety feature of this is that if the engine dies in a major accident that he fuel pump is not continued to be energized and potentially spraying/leaking fuel in a bad circumstance.

if you hooked your Ignition up to it's relay in this fashion then you may only start for a brief moment.. and then die. (ECU trips relay -GND off)

Relay terminal definitions

DIN coding system http://en.wikipedia.org/wiki/DIN_72552

#30 Battery+ direct (should be fused)
#15 Battery+ from Ignition (often unfused)
#85 Relay Coil –Neg (ECU can interrupt GND to trigger i.e. fuel pump relays)
#86 Relay Coil + (commonly the accessory trigger)
#87 +12v power out to accessory/powered item
If equipped with 2 #87 outputs power out on both
Or if labelled 87a & 87b
#87a Normally closed (power output when not triggered)
#87b Normally open (Power output only w/trigger)

Mon May 05, 2014 10:25 am

I know we linked this page from A2Resource above but here's a easier to print jpg image file

Mon May 05, 2014 10:43 am

Erik, you may want to check the TEMP-II sensor it's the blue one(s) in the waaterneck leaving the head to the Radiator
they're not an on the shelf part at the local FLAPS, and I'm not sure if one wasn't reading properly.
I added the 2nd one when I was having issues in the cold in Jan and I'm not sure which one is the one I was last driving on last week ~100mi w/o trouble... they very well are likely both OK. but best to check.

I do apologize for not labeling each/every wire, I wasn't planning to pass the engine along when I removed it, then the next day later your blown engine post came up.

I hate to say I don't know much about the technical specifics on the ECU because it wasn't ever necessary.

and lets see if this link comes thru.
but here's a copy of the VW digifant-II Engine management Service training manual
more than you'd hope to need to know.. I haven't had a need but I like to keep the service manuals handy.

Digifant Engine managment manual

Digifant-II pro training manual
Specifically pages 31-32-33 & 63, 64 regarding fuel pumps shows the wiring to the relays.

Digifant Ignition timing and Idle check

these links uncerimoniously shared from VWvortex at this thread:
http://forums.vwvortex.com/showthread.php?5294505-Teaser-for-some-interesting-things-I-picked-up

Mon May 05, 2014 12:02 pm

per our phone conversation Saturday RE: the Ignition coil
the #15 receives +12v from the key (ignition black wire)
the #1 goes to the Ignition module #1 (have to check wire color)
(Tach hooks to this pole as well if you have one (not diesel tach that goes to W terminal on Alt)

Mon May 05, 2014 8:25 pm

I'd like to thank everyone (Dan especially) for the help so far!

The engine is in, the wiring is mostly complete, and it runs!

Tomorrow night I hope to have most everything finished up.

I still need to:

-install the new fuel tank
-mount the fuel pumps
-tighten all the motor mounts
-install the relay (finish wiring)
-mount the AFM/MAF box and intake filter
-bolt on the CV shafts
-make new hardline for clutch slave/bleed clutch

And it will be done, shouldn't take more than an hour or three to have done tomorrow! [/list]

Mon May 05, 2014 8:40 pm

Now in review:

8 days ago, Sunday April 27

Farmer ingenuity or desperation...

Ready to drop the new engine in yesterday, Sunday May 4

New engine in! Just a few hours ago, around 9:00

Mon May 05, 2014 9:34 pm

WOOT SWEET...
it's odd seeing a faithful old friend in another place.. I usually drive em to the end..
but ~9 days ago I pulled that out of my van to install my 1.8T (AEB) upgrade.. that's now swinging (freely) in my own van..

anyways not to get off your topic..
you may want to rethink the location on the ECU. they don't like heat too much, and the exhaust side will be warmer.
I had it mounted in the side box behind the DS taillight.
just a thought.