EfiMini Wiring

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Fuel Injector and Sensor Wiring

The efiMini is equipped with connectors to provide the electrical hook-up to the vehicle via individual wirings.
This allows a single unit to be used in several different vehicle applications, by providing only the vehicle specific connectivity with the wiring harness and loading a different map configuration for the actually connected engine into the efiMini.

What this means for any shop is, that only one efiMini needs to be stocked, and different wirings for the possibly applicable vehicles.

we need to work on a whole bunch of pics and docs.. please be patience and give us some time.

Universal efiMini injector wiring with open ends. (pics)

Universal efiMini NbO2 sensor wirnig with open ends. (pics)

We also supply any of the efiMini specific wiring connectors and terminals. We also provide some commonly used injector connectors as well as some sources where to get them alternatively.

The terminals are crimp type and would require either an appropriate crimp tool or needle-nose pliers to close the crimp portions and a solder iron to finally solder the wire to provide good electrical connectivity and mechanical strength.



12 V injector rail :

We call the 12 V supply to the injectors 12 V inj-rail and it is mostly common throughout all vehicles. This 12 V supply comes from the ECU and provides the 12 V to the injectors, which are switched to ground by the ECU. There is also the electric fuel pump supplied with this 12 V connection. The ECU provides this 12 V for the 1st 2 plus seconds after ignition switch ON and while the engine is running and being started. If the ignition is turned on without an engine start following the ECU removes this 12 V again with 1 2 second plus delay unit the engine start. What this means is that the determination of the correct injector pin carrying this 12 V can only be done during this 2 second plus period or while starting.
The engine failure light might get tripped if being started with an injector not connected for the purpose of measuring which pin carries the 12 V.

It is advisable to determine which of the 2 injector pins is carrying the 12 V inj-rail with a 12 V lightbulb of 3 W or less (5 W max). Any stronger lightbulb bares the chance to damage the ECUs injector driver.
A 12 V test-light will do the job just fine as well
It is not advisable to perform the 12 V measurements with a volt meter since these will usually have a very high input impedance (10 MOhm) and any electronic connection on the ECUs driver with pull-up capabilities might provide false results. We can't look inside what the individual ECU really does. A 5 W lightbulb will draw a continuous current of 250 mA and represents a 25 % injector load, so it comes close to the load of an injector being hooked up. The cold filament of the lightbulb will force a higher initial current, but this should usually not cause nay problems for the ECU.

The following pics illustrates this 12 V inj-rail voltage test.

EfiMini 12V inj rail.jpg

Connection types :

The efiMini in it's basic form needs only 3 types of connections.

  • power and ground. Power can be supplied by different sources. 12 V connection of injector supply rail. Switched 12 V from the ignition switch or other form of switched 12 V battery supply.

Ground connections can be from the engine (block) ground or the chassis or battery ground. It is mandatory that this ground connection is fixed and can not be accidentally disconnected while operating.

  • TPS and MAP sensor signals need to be tapped into.

pict for TPS and wiper wire detection !!!!!!!!!!!!!!!

  • Injector signals need to be intercepted and routed through the efiMini.

Wiring models :

There are 3 different wiring models with each one only needing a few necessary connections to hook up the efiMini into any existing wiring harness.

These 3 connection models are :

  • intercepting at the peripheral devices :

This could be used if a connectivity at the ECU is too complicated, caused by an ECU main wiring based connector, which can't be opened and individual pins extracted. Or if there are no main wiring interconnect junctions or their connector pairs (male and female) aren't available.
This is also the most simple form of intercepting the injector connections.

The pict below illustrates the interception of fuel injector signals.

EfiMini Intercepted Fuel Injector Connection.jpg

  • intercepting at main wiring interconnect junctions.

Sometimes the main wiring is split into several individual portions. If any of those interconnects contain the injector or TPS circuits, it will be the right place to intercept the signals there and route it to the efiMini.

  • intercepting at the ECU :

If the wiring based connector at the ECU allows disassembly and pin extraction, it is the best place to intercept, cause it contains all the necessary signals. The Harley Davidson fuel injection from Delphi is a good example for this type of interconnect.

example coming as soon as we take pics of this modification.

TPS and MAP Sensor Connection

Signal detection on 3 wire sensors :

For sensor measurements it is mandatory to use a meter instead of light bulbs and light bulb based testers.

There are 2 types of sensors ;

  • the passive, resistive type contains a potentiometer (variable resistor with wiper in the middle) which needs a supply voltage and this voltage gets divided ratio-metric to their resistive values of resistor part to the supply versus resistor part to ground.

The supply voltage is in most cases a regulated 5 V coming from the ECU. Shorting this supply voltage could do some damage to the ECU.

To determine which of the 3 wires is +5 V, which one ground and which one is the sensor wire, connected to the wiper, a simple 3 step approach can be taken. It would be necessary to get electrical access to all 3 wires, by either intercepting it as described later or just tapping into it. Tapping into it could mean having a very pointy needle to poke through the wires insulation and make electrical contact to the conductor strands inside.
In this case it's best to perform these tests with a high impedance volt meter (especially the test for the signal wire). All tests are done with the ignition on and against ground potential and the throttle at idle position.

  1. find the wire which contains the 5 V or closest to it. The highest voltage of the 3 wires and higher than 3.0 V
  2. find the wire which stays stable at or near ground potential while the throttle is being opened and closed multiple times.
  3. the remaining wire where the voltage increases up to at least 2.5 V with opening the throttle is the TPS signal wire. The 2.5 V is assumed to be reached with a high impedance volt meter.
  • for active sensors (MAP or MAF) with electronics inside, the procedure is very similar to the passive one. There is also one wire which supplies the sensor with typically 5 V DC. One with a ground connection and one which contains the sensor voltage. The only real difference is the actuation of the sensor.

With MAP sensors, a vacuum, or if any form of combustion charging (i.e. turbo ...) is applied, a pressure level can be applied in addition to the vacuum for determining the signal wire. </b> While nothing can usually go wrong with applying some kind of a vacuum, with the pressure it needs to be observed that the applied pressure does not exceed the rating of the MAP sensor.
The vacuum can be verified by performing this test with a running engine and rev'ing the engine with closing the throttle afterwards. The closing of the throttle should bring enough vacuum to show a significant sensor signal change.

pics to come

Sensor Connection Types :

There are 3 ways to tap into an existing sensor connection.

  • providing and intercept cable with matching connectors (male and female) and connecting this way to the desired signals. Since in most cases there are only the connectors for connecting to the sensor available and not the connection type representing the sensor itself it is not possible to use this type of connection.
  • non destructive connection to the sensor signals. This can be accomplished by pushing a pointy thin pin with the wire attached to it next to the original wire through the insulating plastic sleeve (see attached pict). While this not be a good permanent solution, it provides a good test vehicle.

The pict below illustrates how to tap into sensor signals with a piece of bare metal wire and an alligator clip (temporary solution). one can solder a stranded wire onto the bare metal wire and once inserted into the connector, wrap it with electrical tape (not to be used if a loose connection can stall the engine or impact the driving of the vehicle). We used it to tap into the ignition signal to get the rpm signal for the dyno. The pict shows a non insulated alligator clip, which is for demo purpose only.

EfiMini Tapping into a Sensor Connection.jpg

  • destructive removal of sensor signal wire isolation and connecting by soldering or other mechanical means.

2 Cylinder Injector Signal Interception

An example of intercepting 2 fuel injectors is seen in the following pict.

EfiMini 2 Cylinder Fuel Injector Signal Interception.jpg

efiMini Main Fuel Injection Interface Connectivity

Below is a diagram of the basic connections from the vehicle wiring to the efiMini. It does not contain the 2 channel O2 sensor hookup, which are not part of the main functionality.

EfiMini Main Fuel Injection Interface Connectivity.jpg

Analyze and Loop-Back Connector

docs coming soon ... need more time ..........................................

Automotive Temperature Wire

We are using automotive grade wires with cross-link insulation for higher temperatures.

This type of wire has the advantage that the insulation does not melt or soften when used at elevated temperatures in engine compartments or near heat generation engine parts. It does NOT imply that it can be routed next to any exhaust pipe or similar. It is not a high temp silicone insulation based wire. It only means that it is better suited near a hot engine than regular wire. It is well worth the extra cost. Please feel free to find your own supplier of automotive thin wall cross-link wires.

We do provide some links, but if you know of another well worth to mention source or product please inform the efiHacks community and us about it.



Pre-fab'ed Wiring

Unfortunately we are right now not at a position to provide complete pre-built wirings for your individual vehicle. However we do provide a universal wiring set with open ends and some shrink tubing to hold it together and let you cut it to length and mount your individual connectors onto the open wire ends.

We will stock some basic injector connector types, but not for all current injector and sensor types.

There is a good source for all kind of automotive connectors and we recommend to take a look at it. (http://connectorsfast.net/shop/index.php?route=product/category&path=33)

If you know of any other, maybe better automotive connector source, please let the efiHacks Community and us know about it.

Note : All published design documentation is Copyright efiLabs.com and its use is without exception FOR NON COMMERCIAL PURPOSE ONLY. For commercial licenses contact efilabs.com ... try us, we're reasonable :)

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