July 31, 2012 Update:

Tried various settings but eventually went with 1 distributer trigger and two inputs. Primary trigger watches rising edge and the secondary watches falling edge for shorter trigger vane. Trigger vane is about 8 degrees, so I used filtering to remove the other vanes. I could not get Cam sync type working, but alien advance seemed to allow VEMS to sync with cylinder 1.

July 24, 2012 Update:

Got the basics of harness built, and updated the [harness schematic] to reflect all the changes I've made. Change are mostly connection pinouts, additional sensors, and re-ordering Coil Drivers.

Following [Step By Step Guide] I soldered most of the board, using as many updated components and procedures as possible. My [Build Sheet Check List] for anybody's who's interested...

As a test to see if things work, I used LEDs in place of injectors and Coils, and drilled the distributor (to spin it with it's hall sensor) and made lights! not on first try tho... placed a couple FETs in wrong spots oops, and fixed! I can now make teh lights blink!

Now onto Calibrations! I have Ford Sensors with 0k to 80k ohm clt and mat, so I found a [member page] about changing pullup resistor on vems board.


using 30785 Ohm (nominal, at 25C) sensor with 32.4 kOhm pullup is same as using 2565 Ohm sensor with the standard 2700 pullup (voltage divider output is same, since *12 applied in both upper and lower resistor)

using 30785 Ohm (nominal, at 25C) sensor with 20 kOhm pullup is same as using 4156 Ohm sensor with the standard 2700 pullup (voltage divider output is same, since *7.4 applied in both upper and lower resistor)

So, a 33KOhm Pull up R8 and R9 and using 3300 temp map gave me the right results for a Ford truck efi sensors:

1990 Manifold Temp sensor and a 1996 Coolant Temp Sensor.

Also, mounted the webshop 250KPa sensor inside of a stock Ford MAP sensor looking thing (it's wasn't a MAP sensor but a DPFE thing for egr) and calibrated. next up is WBo2 [Calibration].

Ok, so after an effin' long hiatus, I've decided to do something with the gen 3.1.

I have a Ford 4.9L (300ci)in a 1978 Truck, and wanting to do away with the single barrel carb. Ford has made this engine up to 1996, and introduced EFI around '87. The engine is shot, bad rings, valve train noisy (maybe the crank?)... so located an 88 EFI 4.9L and will use it as the base for VEMS.

Idea is to be able to modify this engine (Cam, Exhaust, Turbo, etc... fun stuff ;) and have the EFI controller roll with the changes. I'll be doing this in steps, firstly get VEMS working with what's on the 4.9L and introduce enhancements later.

Stage one:

0. Get what I have working, with a fully developed wire harness with spare leads for future expansion.

1. Inventory what I gots:

-I have a 1996 Distributor with a Hall Sensor in it, and 6 tooth wheel and trigger vane is smaller than the rest. more info

-2x GM MAP sensors (1 for dynamic Barometric Pressure Correction). Going to gut one, and place the 2.5 BAR MAP sensor to bring it closer to the manifold.

-Coolant and intake temp sensors, with really high resistance, I may use the NTC temp resistors in them... or GM ones... not sure yet... More info: Coolant Temp and Intake temp

-Ford 80mm MAF sensor pn: xl3f-12b579-ba I really want to use a MAF and not speed density, but not sure how I'm gonna incorporate it... AFAIK, most VEMS installs go with SpeedDensity?. Meh, I'll wire it up, and decide later. More info:

-Ford Stock 4.9L Knock Sensor

-Ford Idle Air Control Valve PWM controlled. more info:

-1996 Ford truck Power Distribution Box, to make things look neat.

-TPS, EGR, Fuel Vapour Canister purge, etc... all from a 90 efi truck.

-6cyl wasted spark coil from a newer Chrysler minivan. Dumb coil, no active electronics.

-6cyl wasted spark coil pack from a Ferd Explorer 4.0l v6 with funky base and funky spark plug wires. not gonna use, and will use Chrysler unit instead.

-4 GM Cobalt Active Coil on Plugs and 8x pigtails! Like mana from heavens, the Dump provides! order three more and I'll have a truck tool box spare! Looking at this [vemssupport] page, I'm going to try [Microchip TC4427]... after I get a crank trigger.

2. a Plan should go somewhere... maybe I'll list it as second!

-Idea is to re-service this old Pickup. Using as much modern equipment for enhanced saftey, green-ness, drivablility, and durability to handle the arctic climate, booney bouncing, water logging, work truck, flat deck, play truck duties I toss at it. So, VEMS it to handle any engine component upgrade, add Catalytic convertor, EGR or other mechanism for controlling Nitrogen-Oxygen emissions.


1. Create Schematic, learn about flyback from inductors (killing 4 or 5 diodes in process, and feeling the voltage from a collapsing starter relay!), pwm led backlight circuits, the myriad low z flyback solutions, Triggers, and goes on and on...

2. Create Harness layout,

How it's going to lay in the truck. where to place harness connection point for servicing, where to poke through firewall, etc..

Test all critical connections and relays on bench.

3. Testing, and Installing.

3a. Motor swap, and VEMS install, and test.

4. enjoy, plan next step

3. Build a schematic so I can build a Harness.

--My [Schematic] in Microsoft Visio I made for learnin' ... lots to take in here... book learnin' Hopefully the vems will survive this electrical environment. As I got, going to add 1n4007 diodes wherever I can on every relay and motor! However, if I miss something or get lazy, the separate Power Distribution Feed should keeps things quiet, electrically.

Am not happy with using three relays to power high and low speed cooling fan from a Taurus (Dump find...). when High speed kicks in, power to low speed should be disconnected, AFAIK. so, had to account for failed relay and/or fuse scenario and not cut power to low speed relay. If it's really hot enough, I don't want low speed cutting out! I am happy I found a relay pack from another Taurus (different dump!) and made it work as though factory put it there. Ford is modular in some of their systems... nice!

If anybody reads this, let me know of any grievous errors.

4. Harness:

What the schematic doesn't show, which I'll hafta scan in, is the Hand draw notes on my Harness build plans. There are three major sections to it:

1. Modified Original. The EFI truck, I sourced this stuff from came to the local dump, which allows us 'scavengers' access to, had the cab with the computer already crushed, and grabbed the rest. so, I have the Injectors harness, TPS area, and Ignition Area harness. I pulled all the pins out and stripped the coverings to expose the wires within. and I found factory batch fired, two batches of three cylinders! Cheep...

2. VEMS harness - VEMS related wiring, connections to the Power Distribution Box, and Modified Original.

3. Power Distribution - Box and bracket taken from a 1996 EFI truck. Stripped of all wires, as in busted open the crimps and pulled the wires off. Doesn't look purdy when the harness has a million splices! re-crimps don't hold as well, and so are soldered.

4. Alternator Harness for [3Gen] [Alternator] [Upgrade] - Slightly modified to fit original ALT light.

Now can upgrade to serpentine belts, and the 1996 Crankshaft Harmonic balancer with 3 finger misfire tone ring. Some ferd history: 1996 Ford Truck had to comply with some OBD2 compliance, and was only year for 4.9L with a crankshaft tone ring. This applies to other truck engines sold by ford in 1996 before the next gen 97 models and it's newer engines.

Next is to machine a wheel to replace the 3 fingered VR with a nice 36 missing tooth gear, which is Stage 2.

Been soldering the original 78 harness as I go as well, and gooping in dielectric compound, and will be slathered with some kinda white grease and then wrapped to keep the mess together... overkill? naw.. ;)

Stage Two:

-I have the 96 crank pulley with a 3 tooth vr sensor ford used for misfire. Plan is to remove the aluminum wheel, and add more standard missing tooth wheel (36-1?) and replace VR with Hall Sensor.

  • Ok, this Jeep, may it R.I.P
I ripped out it's axles and now sits on bare rock. Local kids busted the windows, and now has moss growing on the carpets! I pulled it's harness to fix another heep, so the dash is everywhere inside... mostly broken...

I ain't fixin' it...

So, VEMS my latest uh find... a 70's Yellow w/brown Ford f150 Truck 4x4 with inline 6 engine and cast iron gear boxes (NP435 and NP205). I nicknamed Beauty!

  • Really OLD:

I'm gonna Try and Install a Genboard 3.1 into a Jeep Cherokee (XJ) with a 4.2L I-6 Engine (swapping out the 2.8L GM V-6) and [a GM HEI Distributor Mod] and the older 4.0l (Non-HO) I-6 Intake manifold with Individual Fuel Injectors per Cyl.

My Todo List:

- Update this page with Pics after I get a small Home Web server Going...

- Install Engine into Cherokee and get it running with the Carb.

- Install GM HEI from a Inline GM 6-cyl Distributer

- See if the Intake Manifold will bolt up to the Older Engine

- Brainstorm a trigger wheel... and Install the Genboard as the Winter project. maybe a 36-1 trigger wheel made from a discarded uhm... GM Auto trasmission thingy (I found a web site with info, but lost it...)

- Help with the VEMS-Group Documentation

- Get the Genboard to talk to my computer via the RS232 port

Anybody know if High Z or Low Z Injectors are better for Cold Weather Operation? (-40C to -50C) as I live in the Sub-Arctic...