The Stimulator board allows you to fully bench-test all standard inputs and outputs on your MegaSquirt unit. It will apply power to the MegaSquirt ECU and allow you to simulate engine sensor inputs such as the ignition system RPM signal, the Intake Temperature Sensor, the Coolant Temperature Sensor, Throttle Position Sensor and the Oxygen Sensor. You can manipulate these signals via the potentiometer knobs on the stimulator to simulate different engine running conditions.

During assembly of your MegaSquirt ECU the stimulator is VERY highly recommended. The assembly documentation will actually direct you to use the stimulator to test the ECU at several points during assembly, allowing you to detect any issues before you move on while they are still easier to find and correct.

After assembly, or if you buy a pre-assembled ECU, the stimulator will help you to get familiar with the MegaSquirt and the tuning software before ever attempting to install the ECU on your engine. This is also an excellent tool for testing your Megasquirt ECU while you are working through building your wiring harness. While not an essential or required tool it is highly recommended. If you don't purchase a stimulator for yourself you should at least make sure you know someone who has one that you can borrow if needed.

Understanding the MegaStimulator v2.2 (tweaked excerpt from the MegaManual)

There are 5 LEDs on the Stimulator, and 3 on the MegaSquirt. On the Stimulator, the 4 LEDs are:

• IG (pin 36 Ignition Output) - lights when the ignition is fired on pin 36.
• I2 (Injector #2) - lights when the second injector bank is grounded [injectors firing].
• I1 (Injector #1) - lights when the first injector bank is grounded [injectors firing].
• PMP (Fuel Pump) - lights when the fuel pump relay is grounded.
• IDL (Fast Idle) - lights when the Fast Idle solenoid is activated.

On the MegaSquirt, there are three LEDs, which are:

• Injectors - lights when either injector bank is instructed to be grounded [firing].
• Warm Up Active- lights when Warm-up Enrichment (WE) is activated.
• Accel Enrich Active - lights when Acceleration Enrichment (AE) is activated.

   

Note that these LEDs all do separate things.

The Injector LED on the MegaSquirt lights when either Injector bank is commanded to fire, while the injector LEDs on the Stimulator light when each injector bank actually is grounded. The MegaSquirt LED will flash synchronously with the Stimulator Injector LEDs in simultaneous mode, and will flash twice as fast as either LED in alternating mode.

The Warm-up Enrichment values are separate entries in the software from the Fast Idle Threshold value, so these two LEDs will generally light at different, though similar, coolant temperatures.

The Fuel Pump LED is light whenever the fuel pump relay is grounded. Since the Stimulator puts out about 1 pulse per second minimum, and the MegaSquirt leaves the pump on for 2 seconds after the last ignition event, the fuel pump LED should be light whenever the Stimulator is plugged into the MegaSquirt.

By using these LEDs, and adjusting the RPM, coolant and air temperature, EGO, and throttle potentiometers on the MegaStimulator, while viewing the PC Configurator or MegaTune tuning software, you ought to be able to test every function of your MegaSquirt, except MAP function [for which you can suck and blow].