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[Datsun 1200 encyclopedia]

EGI MegaSquirt

From Datsun 1200 Club

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Category: Fuel Injection

Buy MegaSquirt II (or MicroSquirt 2) fully assembled about $400 USD or $500 AUD off eBay.


Manifold and Injectors

Obtain an A14 or A15 EGI factory Datsun fuel injection manifold.

8104.jpgAlbum click to view

Make sure it includes:

  • the factory rising rate regulator and fuel rail
  • the fuel injectors included
  • the factory 2-pin water temp sensor
  • the throttle body. The Factory one is good for 92 hp
  • the air regulator. It will run without this if you want to hold your foot on the throttle while engine is warming up to 120F/45C

Everything else may be removed from the manifold.

  • if you remove the EGR passage, fit a blocking plate
  • an O2 sensor is not required
  • TPS is not needed

the only vacuum hoses needed are

  • one to the fuel regulator
  • one from the throttle body to the distributor
  • manifold to MegaSquirt


With MegaSquirt you won't need the Datsun airflow meter. Instead, Megasquirt will calculate the air mass using a MAP sensor and and IAT sensor.

  • MAP sensor is built into Megasquirt. Connect vacuum hose to manifold
  • Obtain GM IAT sensor from a Chevrolet or Holden. Drill hole in your air cleaner-to-throttle body pipe, and hot-glue the IAT in place. Or use JB-weld. Threaded bungs are available if you want to get really fancy.
* MegaManual
* GM IAT Sensor 12146312 $10
* GM sensor connector 12162193 $5 

Fuel System

Use a 280ZX fuel pump (or Walbro inline pump), connected to the stock fuel line coming from the tank.

* 280ZX Fuel Pump $45

Run a regular fuel line back to the the filler hose and Tee it in. If you keep the tank above 1/4 full no baffles or surge tank are needed.

From the fuel pump output to the fuel rail, use EFI-rated fuel hose and EFI hose clamps. Use a 280ZX-style fuel filter.

Nissan EFI fuel pump with damper can be mounted in rear of car or in engine compartment
21845.jpgAlbum click to view

280ZX EFI fuel filter $3


Wire up the MegaSquirt harness

  • 12V
  • earth/ground
  • fuel pump relay
  • injectors
  • IAT signal & ground/earth
  • Air Regulator
  • EFI Water Temp
  • Tach signal (coil negative terminal)

For full details, see

Obtain a dropping resistor pack, and connect to injectors
21853.jpgAlbum click to view

See main article: Dropping_Resistor


ECU Configuration

Download at

  • Mac
  • Windows
  • Linux

You have a choice:

  • TunerStudio free version (most popular software for MegaSquirt)
    Free version supports all MegaSquirt features
  • SuperTunix open source

In the software configure

Fast Idle Valve (FIdle): Solenoid
Fast Idle Threshold: 120F
Nissan temp sensor
-40F 30-33000 ohms
 80F 2000-2500ohms
160F 360 ohms
Required Fuel
* displacement 1397cc (A14) or 1488cc (A15)
* # of cyl 4
* injector flow rate 188
* desired AFR 13
Injector open time 1.0ms
batt V correction .20
PWM current limit 1000%
PWM time threshold  25.4
Fast Idle Threshold
Barometric Correction: Off
Control Algorithm: Speed Density [non-TPS]
Injections per Engine Cycle: 1 squirt
Injector Staging: simultaneous
Injector Port Type: multi-port
Engine Type: even fire

Generate a new table based on your peak horsepower and torque figures ('Settings/VE Table/Tools/VE Specific/Generate VETable').

EGO Step (%): 0
Warmup enrichment
-40F 180%
-20F 150%
 0F 140%
 20F 135%
 40F 130%
 60F 125%
 80F 118%
100F 110%
130F 103%
160F 100%

Afterstart Enrichment: between 25-45%for 100 to 250 cycles,

Software Tuning

Start your engine and let idle. Go to

And start tuning.

A big help in turning is to fit an Air Fuel Ratio Gauge. MegaSquirt 2 can directly read the wideband output of the wideband controller, but more importantly you can see the A/F Ratio on the gauge.

 See Main Article: Oxygen_Sensor#Air_Fuel_Ratio_Gauge


The paid version of TunerStudio has a software auto-tuner which is supposed to be great, but it still requires some work (it's not totally automatic). 

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This page has been accessed 11,703 times. This page was last modified 23:48, 2 August 2017. Content is available under Datsun 1200 Club.