How To Megasquirt Your 2nd Gen RX-7: Prerequisites And Requirements

There are several requirements and prerequisites that must be met before the Megasquirt installation is to take place.

The Car

The Car Must Be In Good Running Condition

Before you start it is important that the car be in proper working order. It should run well on the stock ECU and not have problems like bad sensors or vacuum leaks. It should receive a full tune up, the injectors should be clean and there should be no mechanical issues. Starting with a car that does not run would be considered an advanced installation because it is impossible to know the condition of any of the components. Maybe the coils are bad? Maybe an injector is clogged? The fuel pump may be burned out. Any of these issues can quickly complicate a standalone installation whether it be Megasquirt or any other EMS.

The "Throttle Body Mod" Should Be Applied

This is not a hard and fast rule, but will be beneficial in the end. The tertiary set of throttle plates in the TII is there to smooth throttle transitions. In the NA, it is there to prevent wide open throttle when the engine is cold. As we can now tune the car better then the factory ECU, and no self-respecting driver will floor the car when it is cold, these can be removed. While not part of the throttle body mod, removal of the thermowax and coolant feed to the throttle body is often lumped in. While absolutely a bad idea on a stock ECU street driven car, the whole cold start cam and thermowax is unnecessary with a standalone as the BAC now takes over it's functions. You will find a great writeup on performing the throttle body mod at FC3S Pro

Emissions Equipment Needs To Be Removed

As the Megasquirt is an aftermarket ECU for off road use only, it cannot control the stock emissions equipment. Therefore, an emissions removal must be performed on the vehicle. Rotary Resurrection has a good set of articles on emissions removal for S4 NA, S4 TII, S5 NA and S5 TII. You can also find similar articles by searching the RX-7 Forum. However, no matter what any emissions removal article you may read says, do not remove the BAC valve. This writeup makes full use of the BAC valve for warmup idle, idle regulation and dashpot function. For the record, it is crazy under almost any circumstance to remove the BAC.

The BAC Valve Must Be Installed

As I mentioned above, the BAC valve must be present. The stock ECU uses the BAC valve to control engine idle speed and the Megasquirt is no different. We will be modding the 'Squirt to run the BAC valve. It will be used for the fast idle when cold, normal idle regulation when warm, and to electronically replace the mechanical dashpot that was removed with the throttle body mod. If you don't have a BAC valve on the car, go get one and install it.

You

You Must Have Some Mechanical Ability

You're going to need to know how to work on your car. How to remove and reinstall the intake manifold, how to work with the vacuum system, etc. General mechanical ability is going to be required.

You Are Going To Need Some Electronics Knowledge

Or, at least have access to someone who does. The Megasquirt needs to be modified (or built, if you go with a kit!) and of course the whole system needs to be wired in. You need to be comfortable with automotive wiring, know the basic concepts of soldering and making a loom, etc. If you don't have these skills, access to a friend who does is also acceptable. It may just cost you a lot of beer by the time the install is finished...

You Need A Place To Work

A nice place to carry out this project is important not only because you need space, but your mental health depends on it. There is nothing more frustrating then working in a confined area with barely enough room to work, or having to step over disassembled parts. The car will be stationary for at least a few days or more realistically a week. If you choose to assemble your Megasquirt from a kit, you will need a well lighted work bench with a comfortable stool or chair.

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