Last updated: January 24, 2016

Project "Ultimate 1983 Rabbit GTI"
Electrical & Fuel System ...


Index of Project web pages

Project Overview, Goals & Initial design specs
Project car initial condition
Chassis development
Bodywork & Paint
Suspension, Wheels, Tires & Braking System
Engine & Transmission

Electrical & Fuel System
Performance validation
VW Vortex Thread on this project
My original 1983 Rabbit GTI (owned 1983-1987)


For the engine management system I have chosen what I beleive to be the most advanced ECU available in the market today: the Holly Dominator EFI system. It is a self-learning/mapping system that senses all fuel to air ratios via a wideband O2 sensor - this is a really powerful and unique feature.



Here is a partial list of features:


I picked up the complete ECU system (sourced from Kinsler Injection) - boy there are a lot of wires that will need to be connected. I also picked up the remaining engine sensors and plumbing components from Techtonics ... - May 3, 2014


NOS Wizards Quadranoid, a dry flow nozzle, and small ID plastic tubing ...


I am epoxy coating the fuel tank before installation - July 20, 2014


With the final painting complete I can now get on with planning and executing the fuel and brake system installation - August 17, 2014


It was a tight sqeeze but I managed to route the fuel tank breathers together such that I can now install a rollover valve in the fuel filler neck area of the wheel well. I got the pump and filters final-mounted and the hoses routed as well. The Techtonics SS 2.25" exhaust system installation has also started but I was very frustrated with a few things that are only partially resolved at this moment: a serious interference fit with the driver side tank strap which required that I fabricate a bracket to allow the removal of the strap, plus I can't get the resonator to sit in the middle of the tunnel without an interference fit with the front hanger on the side of the tunnel (I think I will end up cutting and rewelding some pipe to solve this). The bottom line is that all of the really hard problems with the fuel system are now behind me and the exhaust system issues are on the way to being solved. I will need to mount the engine and exhaust racing header before making any final decisions on the exhaust system though - September 1, 2014


The final fuel system plumbing involved fabricating some stainless brackets to allow for clean and safe mounting of the supply and return lines - November 11, 2014


I bit the bullet and upgraded from the Holley HP EFI system to the full Holley Dominator EFI system with its endless # of inputs and outputs. In the end I needed to control more things like 2 PWM fan outputs, a PWM water pump output, and more sensor monitoring (e.g. a second water temperature sensor in the radiator allows me to monitor the difference between the rad and block temperatures and adjust pump flow rates and/or put a restrictor plate into the system to avoid 'block shock'). I am also going to use the Racepak UDX LCD console which communicates with the Holley EFI ECU via can-bus - January 18, 2015


I finally sourced all of the fittings required to create a 'push' compressed air nitrous system (4500psi carbon air bottle with a 2900psi output regulator, a 3000psi solenoid, a 550-1250psi adjustable nitrous pressure switch, and the tricky NTP to BSPP adapter required to connect the air quick-disconnect fitting) - March 8, 2015


After fighting with the old heater valve cable for about 2 hours (trying to lubricate it so that it would slide smoothly and open/close the heater valve) I gave up and found a replacement Gemo p/n 161819837 on ebay that looks like it will work fine in my mk1 application. I then fitted up the remaining cables that were in perfect working condition and mounted the heater/HVAC box in the chassis with its new gaskets. I was then able to hook up and complete the coolant system lines in the engine bay and pressure test the complete system to 15psi - success! I was also able to install many of the engine sensors and started to design a mounting bracket for the Holley Dominator ECU and ignition coils that will be placed in the rain tray on the passenger side (it is all weather proof but won't really see any water where it will be placed) - April 25, 2015


I am starting to lay out the wiring harnesses and plan my connectors (a combination of metripack and weatherpack connectors). I had to cut away all of the electrical tape on the main ECU wiring harness as Holley had placed the fuel pump & injector relay and fuse in a crappy location for my project, same with the main power fuse.

I semi-finished my ECU/ignition system mounting system/plate, ordered and wired up the custom Magnecore KV85 silicon ignition wires and fabricated a wiring loom to hold the wires to the back of the cylinder head. I am pretty happy with how they look.

I sorted out the remaining engine sensors and tested/modified them to suit my project. The cam and crank sensors have given me the most challenges. I had to basically build a custom cam sensor earlier on in the project, and for the crank sensor I adapted a late model Bosch hall effect sensor that didn't quite fit the VW ABA block so I had to grind away at it a lot and also solder up a custom connector that would not hit the block but in the end I was rewarded with a high quality digital output to the ECU. For the cam sensor I got it setup properly to trigger at 180 degrees before Cyl #1 TDC which is what the ECU wants to see. Just prior to firing up the engine for the 1st time I will test all of the ignition timing with the injector harness disconnected.

Here is a list of the main engine sensors (email me if you need the p/ns for the mating connectors):

Bosch KS-R knock sensor, p/n 0 261 231 047 (analog peizo output, ECU set to monitor at 7.2kHz)

Bosch Hall-Effect Speed Sensor HA-P, p/n 0 232 103 037 (requires 1k pullup output resistor)

BBHME2000 Hall- Effect Cam Sensor (requires 1k pullup output resistor)

- May 12, 2015

My new Magnecore ignition wire set and loom ...

Comparing the stock ABA inductive crank position sensor IA-C (p/n 0 261 210 136) to the later hall-effect sensor I used ....

Modifying the later model hall-effect sensor ...

Testing the crank position sensor ...


The past 10 days have involved a lot of electrical parts sourcing and planning as I have come to the realization that it is simply not practical to just wire up the engine ECU and fire up the engine without planning and executing the foundational electrical system before hand. Something as simple as routing a wire thru the firewall requires that the location of the wiring harness be pre-determined and also that any gaskets already be in place (and the gaskets are sometimes hard to source). I also made the tough call to bail on using part of the stock wiring harness and instead will completely rewire the GTI end to end so I have made up a nice flip-down wiring panel under the glove compartment that will hold all of the distribution panels/fuses, and relays. I also determined that a 20AH Lithium Pros Battery would be my power source (Lithium batteries have a very flat discharge curve and can be deep discharged making a 20AH capacity battery equal to a 30AH lead-acid battery and it weighs 7.5lbs vs 30lbs) so I ordered one. I plan on running 1/0 flexible welding wire from the trunk to the wiring panel, passing thru a remote/wireless controlled 150amp disconnect switch and a 200amp current shunt (to allow the ECU to monitor the charge/discharge rate of the battery), then controlling the switched +12V via a traditional 150amp continous duty solenoid which will then feed all of the fuse panels and relays. All mechanical switches will be replaced by ECU/Digital display touch panel controlled virtual switches, including things like the emergency flashers, various lights, seat heats (continously variable heat control by computer) etc. Even the old turn signals and driving lights will be controlled via the virtual switches by feeding the dash/stalk switch outputs to the ECU inputs and then the ECU outputs will drive the 50% duty cycle relay controlled turn signal outputs, etc. - all using the Holley Digital Dash unit (by using the Dominator ECU I have tons of assignable I/O pins so I might as well take advantage of the same technologies used in software controlled cars like the Tesla). I also sourced a Kicker IQ1000.5 1200W RMS amp for the audio system which is all software programmable and streamed to by bluetooth - May 28, 2015

Test fitting in the stock dash to determine wiring panel installation parameters ...

Fabricating a flip down 1/4" Lexan mounting plate for the relay and fuse panels under the glove compartment ...

Death to the old stock wiring harness (rats nest) ...

A portion of the wiring materials I will be using to completely rewired the GTI ...

1200 watts RMS with full digital EQ and Bluetooth control/streaming ...


Major score today! I was wandering around the local automotive parts store looking for some electrical supplies and out of the corner of my eye I spotted what looked like a VW mk1 US spec light bulb holder on the rack of GM connectors. On closer examination I located what looked like all of the major bulb holders for my Rabbit GTI and took them home to verify that indeed these were the correct replacement parts. This makes total sense as the US VW engineers would have had to meet US DOT lighting requirements so why not dive into the local Detroit parts bins and borrow a few things? Here are the part #s:

Front turn signal bulb holders: GM 88860442
Rear side turn signal bulb holders: GM6298892
Rear 2 circuit bulb holders (4 required): GM 12003758
Rear 3 circuit bulb holders (4 required): GM 12003759

All of the bulbs for these holders can be sourced in LED format which is what I have done, with an eye on keeping the same level of brightness as the original bulbs (you have to be careful as most LED replacement bulbs are lower brightness) - June 2, 2015


I got all of the fuse blocks, regular and micro relay blocks arranged on the panel that will mount under the glove box and will drill holes and start to mount everything this weekend. I also got the LED lights mounted in the housings with the new GM bulb holders and tested out their brightness (they modestly exceed the brightness of the OEM bulbs but require a dimmer 47 ohm resistor for the dual brightness settings to match the stock look). There are also a few minor clearancing issues with the LED bulbs that require a bit of work with a dremel to allow them to fit in a few of the holders. Here's the info on the bulbs I used which were ordered from

Product ID: 25454
Product Name: S25 27 SMD 5730 10-30V AC-DC
Attributes: Color - Warm White 3000K Base Type - 1156 Single Circuit
Price: $8.61

Product ID: 25454
Product Name: S25 27 SMD 5730 10-30V AC-DC
Attributes: Color - Warm White 3000K Base Type - 1157 Dual Circuit
Price: $8.17

Product ID: 45689
Product Name: T10 Wedge 5 Ultra Bright SMD LED Bulb 1.5W W5W 12 VDC T3 1/4
Attributes: T10 Color - Super White
Price: $3.58

- June 5, 2015


I was tired of smelling raw gas in the garage and did some research on what racers do to safely and properly vent their gas tanks without the loss of fuel vapour and the answer turned out to be a trick invention from a UK company that makes a bi-directional fuel tank vent valve that releases pressure inwardly at 0.05psi (for when the fuel pump is sucking and needs air intake) and outwardly at 0.7psi for when the temperature of the fuel tank as warmed up substantially and excess pressure needs to be released. This keeps the tank vent closed in normal use and nicely eliminates the smell of fuel vapour in the garage. I did also find that the fuel level sender gasket wasn't sealing perfectly so I added some silicon sealant to it and that solved that problem. Finally, I added thin -6AN aircraft crush washers to all of the engine compartment -6AN fuel fittings to ensure that they were absolutely sealed - the problem of sealing AN fuel fittings seems to come from combining fittings from different manufacturers - just a precautionary measure.

I put a ton of time into wiring the ECU harness and installing it into the chassis. I think it will take another 2 weeks to complete all of the chassis/engine/ECU wiring and then it will be time to finally fire up the engine - June 15, 2015

The TPV6 fuel tank vent value assembly ...

ECU wiring madness ...



The fuse/relay panel was finished and installed in the car - now the wiring looms need to be terminated and attached to the relays and fuse blocks. I sourced original AM/FM cassette decks for the car as well: A Blaupunkt Denver SQL26 which looks very close to the OEM cassette deck (does anyone have a hi res photo of the original one?), and a mint condition Concord HPL-130/dBx AM/FM cassette deck (this is the model I installed in my GTI in 1983). I also got more wiring done in the chassis - June 29, 2015

My hydraulic battery lug crimper (12 tons of force) - a worthwhile $75 Amazon purchase ...


As part of my engine ECU wiring I had to run the low voltage and high voltage wires next to each other for a short distance so I did a careful job of shielding them fully. These photos were taken before wrapping all of the shielding in protective tape and then applying the final plastic conduit to them - July 22, 2015


[Background: as a young electrical engineer 30 years ago I designed power supplies and battery charging systems for mobile devices]

I was very excited to be able to use the latest greatest automotive grade Lithium ion ferrous phosphate battery technology from Lithium Pros as they are vasty superior to lead acid batteries in several ways: very flat discharge curve (the battery voltage stays high); high high cranking amps without voltage drop (cranking at 12.8V, not 10-11v); very fast charging (all of the available energy from the alternator is immediately stored); many times greater cycle life; deep discharge capability (you can use all of the capacity without damage); and light weight.

But the negatives are: poor performance in sub-zero temperatures; and a less than ideal match to standard automotive alternators that put out 14.4V when Lithium batteries don't want to be charged at more than 3.4V/cell = 13.6V. On-board battery management systems try to shunt the additional voltage and excess current thru internal discharge resistors and it sort-of works but the ideal situation would be an intelligent computer controlled alternator regulator that can rapidly charge the Lithium battery and then back off ... enter my latest project idea ...

I built a circuit that allows full alternator voltage up to 13.6V and then limits it to 13.8V - it does this under ECU control by monitoring the battery voltage and then spoofing the alternator into thinking that it has reached 14.5V by outputting higher than actual voltage back to the alternator 'sense' wire. It uses a charge pump circuit to get 16v to the op amps, and the PWM output of the ECU to send signals to the circuit to increase or decrease the Vsense line. It works perfectly and now I have a charging system that won't limit the life expectancy of the $1200 battery I have.

And I completed the associated battery charge/discharge ECU monitoring circuit which consists of a 75mV/200A shunt in series with the battery and a bi-directional differential voltage amplifier/monitor that puts out a 0-5V signal to the ECU (2.5V = 0 amps, 0V = 66 amps charging, 5V = 66 amps load) ...

I also received my midnight blue headliner material from SMS - it is a perfect match to the VW OEM fabric and is nicely foam backed ... - November 17, 2015


For the last few weeks I have been working on the rear wiring and lights, starting by building a new rear wiring harness with all new connectors and LED lights (see prior posts for p/ns), plus I worked on coloring the Hella replacement tail light assemblies to be a hybrid of a US and Euro Spec look to them (I am also building aluminum/carbon fiber bumpers that will be a hybrid of US and Euro Spec look to them - shaped like the US bumpers but scaled a bit smaller and closer to the body). I got the powered radio antenna installed in the back, plus sorted out the backup camera mounting and wiring, although I blew up the camera by connecting it to 12V when it needed 3.3V. I also got the 12.9 grade rear axle mounting bolts installed with the Lella AutoSport 15mm spacers - January 17, 2016

The old wiring harness ...

The new wiring harness ...

The Boyo rear view mirror and backup camera ...

Painting the Hella US Spec tail-light assemblies to look 1/2 like the original US Rabbit GTI units and 1/2 like the Euro spec units (black top and bottoms but no black lines in-between the lens) ...

Drilling out the sheet metal screw holes for the side markers and license plate lamps to accept M4 slainless nuts and bolts (I will use black oxide button head screws for the side markers when they arrive) ...


I finally got to the point where I had all of the parts necessary to assemble and bench test the electrical A/C system. I used low temperature aluminum/copper solder (500 degree F) and I didn't really do a very good job on the receiver/drier connectors as I didn't apply the massive amounts of flux that that particular solder requires - so I had to re-solder a few places and still need to chase down a few remaining leaks (I have ordered Harris Al-Cor brazing wire and will re-do all of the connectors and I may also switch over to flex lines ...). All of the copper compression fittings are leak-free but another set of leaks occurred after 24 hours at the NPT teflon tape fittings as the POE oil in the system actually dissolves teflon tape - so I replaced the white tape with yellow gas spec tape and it seems to hold better (we'll see ...). The system was charged up with R134a refrigerant and it came to life. It will need tuning to bring out its maximum potential: the oil coolers I am currently using as the evaporator and condenser cores aren't very thermally efficient when used in an A/C system and so I will look more into finding small A/C cores that will fit my application, plus I need to determine the ideal R134a charge load - I added too much at one point in my testing and the performance dropped almost to zero (I think the low side pressure should be around 25psi and it was up to 40psi). With a medium-high fan setting I saw about an 8 degree F drop in air temperature coming thru the evaporator and I'd like to see more like 10-15 degrees drop (this compares to commercial systems that are >4x more powerful and can drop the air temperatures from 80+ degrees F to below 50 degrees F) - January 24, 2016



Index of Project web pages

Project Overview, Goals & Initial design specs
Project car initial condition
Chassis development
Bodywork & Paint
Suspension, Wheels, Tires & Braking System
Engine & Transmission

Electrical & Fuel System
Performance validation
VW Vortex Thread on this project
My original 1983 Rabbit GTI (owned 1983-1987)



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