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V3 MicroSquirt® - QuickStart Guide

Configuring Your V3 MicroSquirt® Controller

Tuning Software

The software application you use to tune and configure your MicroSquirt® controller is called TunerStudioMS by Phil Tobin.

You also need Java-enabled PC and a conventional serial port to communicate with your MicroSquirt® controller. USB will may work, and many people have reported that they have been successful using a USB-serial adapter. Just about any computer that is capable of booting Windows 95 (or better) will be fast enough, but get the fastest laptop computer you think is reasonably priced.

To tune all the parameters of MicroSquirt® controller so that your engine runs the best it can, you will need to do the following:

  1. First, install and learn to use TunerStudioMS,
  2. Next, set the constants,
  3. Get the engine started and idling,
  4. Then tune the cold start and warm-up enrichments (and IAC parameters, if you have one),
  5. Then tune the VE table, the AFR table, and the spark advance table,
  6. Finally, set the acceleration enrichments,

This section of the manual covers the first two items. The remaining items are covered in the 'Tuning Your MicroSquirt® Controller' section.

General Advice and Operation

Some general principles to follow when setting the configuration parameters are:

Note that it is possible to damage your engine and/or MicroSquirt® controller by choosing inappropriate tuning or set-up parameters in TunerStudioMS. Be sure to read this document, and all associated tuning documents that apply to your engine, vehicle, and tuning circumstances. In particular, read the safety precautions.

  • Install and launch TunerStudioMS. Double-click the TunerStudioMS icon (created above) on the desktop. In order to communicate with your MicroSquirt® controller, you may need to set the serial port configuration. To do this, got to the Communications/Settings dialog on the TunerStudioMS menu.

    When TunerStudioMS is loaded and communicating with your MicroSquirt® controller, the first thing you will see is the front page. A number of the sensor readings are displayed, as well as some outputs. For example, the injector pulse width is the measure in milliseconds of how long the injector is opened for each pulse, regardless of how many times it is opened in a cycle. Duty cycle gives the percentage of time the injector is open irrespective of individual pulse duration.

    TunerStudioMS+ allows you to save and restore configurations as disk files (they have an .msq extension). Use the 'File→Open, Save and Save As' menu items to do this.

    Setting the General Parameters

    Note that as the code develops, some advanced options may not be documented here. To find information on these advanced options, see the TunerStudioMS help file.

    Some general principles to follow when setting the configuration parameters are:

    Now we are ready to start configuring your MicroSquirt® controller!

    On the main TunerStudioMS menu is an item called 'Settings/General'.

    You can set these as follows:

    If you are using a knock sensor, separate baro sensor, or non-standard MAP sensor, you can configure your MicroSquirt® controller to work with them using the 'Sensor Calibration' dialog under 'Tools'.

    The code in your MicroSquirt® controller is set up for the standard General Motors temperature sensors. If you are using other sensors, you can use the 'Calibrate Thermistor Tables' dialog under 'Tools'. You enter the bias resistor value (2490 Ohms for your MicroSquirt® controller) and three temperature/resistance points, and the table is created and downloaded to your MicroSquirt® controller for you.

    If you are using temperatures sensors in a high temperature application such as an air cooled engine, see: Air Cooled Engines and Other High Temperature Applications

    IMPORTANT NOTE: Do NOT burn tables ('Calibrate AFR Table' or 'Calibrate Thermistor Tables') on a running engine. Even idle is NOT allowed, because these tables ONLY exist in flash, so once a table is erased, there is nothing but garbage in there until it is re-programmed, one word at a time. Until that reprogramming is complete, operating the engine is unsafe.

    Idle Control Settings

    The basic idea of IAC is that the motor or PWM solenoid starts out with a large opening of the air valve at cold startup, then gradually closes as the coolant temperature rises. The basic motor position at any given time is determined from the input table of step position versus coolant temperature. To this basic control algorithm, several features have been added as described below.

    Note: If you have an IAC stepper motor, you cannot control this with your MicroSquirt® controller.

    Setting the Injector Criteria

    Before attempting to start your MicroSquirt® controller equipped engine, you will need to set a number of parameters that determine how your MicroSquirt® controller injects fuel. These include the injector open time, Req_Fuel, injector control criteria, EGO characteristics, etc. These constants are either calculated, or based on the configuration of your system. For the most part, these are very similar to those from MegaSquirt-II™.

    Note that for a Wankel rotary engine (Mazda 13B, etc.), see the MegaSquirt & Rotary Engines document for settings and other advice.

    On the Settings/Injector Characteristics page:

    High impedance injectors (> 10 Ohms) can run on 12 Volts without problems. Low-impedance injectors require some form of current limiting. For low-impedance injectors (less than 3 Ohms), must add resistors in series with the injectors. See the Injectors and Fuel Supply section of the your MicroSquirt® controller manual for more details.

    On the 'EGO Control' page:

    Note that after you select your EGO sensor type, you should go to the 'Tools/Calibrate AFR Table' dialog and select the sensor output curve.

    For example, if you have a narrow band sensor, select that; or if you have a DIY-WB controller select that, etc. Then click on the 'OK' button and a file will be create and downloaded to your MicroSquirt® controller that indicates the corresponding air/fuel ratio for various sensor/controller output voltages.

    You can also create your own custom table by entering two point on the output curve.

    There is more information on how to use these settings while tuning in the Tuning section.

    IMPORTANT NOTE: Do NOT burn tables ('Calibrate AFR Table' or 'Calibrate Thermistor Tables') on a running engine. Even idle is NOT allowed, because these tables ONLY exist in flash, so once a table is erased, there is nothing but garbage in there until it is re-programmed, one word at a time. Until that reprogramming is complete, operating the engine is unsafe.

    Setting the Tables:

    Before starting your engine, you need to populate three types of tables: the VE table(s), the AFR table(s), and the ignition advance table.

    Setting the Ignition Options

    Your MicroSquirt® controller has a number of ignition options:

    If you are not entirely sure about your ignition settings, check the supported list for the settings you should use:

    If your module isn't on the 'officially supported' list yet, you'll need to understand the relationship between the trigger offset, the input capture (falling or rising edge), and the spark out (going high or going low). There are some tip on setting these parameters in the tuning section of the MS-II manual.

    In the 'Settings/Ignition Options' dialog you can select the:

    Dwell Setting

    Dwell is the length of time the coil charges to make each spark. It has to be long enough to make a decent spark, but too long heats the coil unnecessarily. It is in milliseconds, since the time between spark is typically a few dozen or less milliseconds. For example, for a V8 at 600 rpm, the time between sparks is 25 milliseconds. At 6000 rpm the time is just 2.5 milliseconds.

    MAP Sensor

    If you have a MAP sensor that does not match the default table in your MicroSquirt® controller (i.e., not the default MPX4250AP), then you need to do a calibration under 'Tools/Sensor Calibration'. You need to set both the MAP and barometer sensor to match the sensor(s) you are using. Press F1 while in the sensor calibration dialog to see values for some common sensors. See the MAP sensor calibration section of the manual for more information.

    Therer are many more configuration parameters for your MicroSquirt® controller, you can find them all here:

    Once you have configured your MicroSquirt® controller, you can start tuning it, see: Tuning Your V3 MicroSquirt® Controller

    If you have any questions or problems that can't be answered from the links above, or a search the MicroSquirt® manual:

    you can ask questions at the MicroSquirt® support forum which is at: Click the links for more information.

    MicroSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
    MicroSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a MicroSquirt® or MicroSquirt® controller is legal for your application.
    ©2004, 2011 Bruce Bowling and Al Grippo. All rights reserved. MicroSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of V3 MicroSquirt® boards from Bowling and Grippo.