l28et vems standalone

[Luke280turbo]

Hello everyone my name is luke and i have a 74 Datsun 260z l28et project that I'm going to be documenting my progress on . I swapped an 81 l28et into it and am currently doing a Vems v3.7 install. I want to make a thorough write up to make standalone install on these motors (or in general) easy to understand. In my setup my motor is mostly stock except for the Vems, a straight exhaust and the common deletes (egr,ac, etc...) 
In this write up I will cover the basic aspects of engine management. Crank/cam sensors, injectors, ignition, map sensor, coolant temp sensor, TPS, and O2/egt sensor 

CRANK SENSOR- for my crank sensor I will experiment with using the stock 81 l28et toothed CAS wheel (90 tooth) with a retrofit VR sensor as this is what my Vems is configured for. the setup picks up a signal on cranking but i have not yet ran the car on it.

INJECTORS- the injectors I am using are the stock l28et injectors. These are low impedance (ohm) and there are 2 ways to drive these injectors. This is general and applies to most if not all ECU's from MS to Vems to Electromotive. The first and more preferred way to drive low z injectors is PWM (pulse width modulation) this modulates current during injector hold (open) time to prevent injectors from overheating (with this method the you don't use inline resistors). The second method which I am doing is to run inline resistors on every injector and drive them as you would normal high z injectors. L28et injectors are approximately 2.2-2.3 ohms and I will be running a 50w 6ohm heatsink resistor inline on each injector. I will be putting the resistors on the ground(computer) side of the injectors . They will be mounted in the car near the ECU. Injectors are wired independently for sequential injection.

TPS- in my setup I use a GM TPS 5v 3 wire. most TPS that are continuous not switch type will work. The stock one i believe is a 3 position switch. this will not work. I made 2 small brackets to mount it to the l28et throttle body.

IAT- for my intake air temperature sensor I also used a GM IAT. It may be tricky to find a good spot to mount it keep in mind it has to be in the manifold area (after the turbo). 

MAP- for my manifold air pressure sensor I simply used the supplied Vems internal sensor. My pre assembled Vems unit has an internal 3-bar MAP sensor. There is a vacuum hose output on the ECU that is ran to a port on the intake manifold. Very convenient and simple.

IGNITION- for my ignition setup I will be using a single coil ran through the stock dizzy. I will experiment with using the internal Vems igniter and using the stock l28et coil/igniter. Coil has +batt on one side and the other ground side goes right in the computer (coil-0) this is the simplest setup. In the future I plan on goin coil on plug or do a 3 coil setup. If you are doing a coil on plug setup you have to remember it's going to be waste spark Unless you have a cam position sensor (which simply indexes whether the motor is on exhaust or compression stroke).

CTS- I have not decided on what coolant temp sensor I'm going to use Yet. The stock one is a 1 wire and I believe is useless. I believe GM sensors have the same size/thread. I will experiment with CTS and let you guys know what fits into my thermostat housing.

O2 - For the oxygen sensor I will remove the old 1 wire sensor which is also useless and use a Bosch Wideband sensor. i believe The particular Bosch o2 is somewhat specific to Vems and I believe can even be used from any Audi/vw 1.8t. Wideband O2 sensors are essential in tuning a car. Vems have built in Wideband controllers so all I will need is the sensor which is under 100$. 

please correct me if any of my information is wrong. i anticipate to do the first start in about 1-2 weeks. i will continue to keep everyone updated and hopefully post some pictures soon.