Initial RPM testing with an MS2 or MS3

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Initial RPM testing with an MS2 or MS3

Postby jbelanger » Thu Mar 26, 2015 8:45 pm

This post gives a description of the first tests that should be done to make sure you have an RPM reading from the JimStim on your MS2 or MS3 ECU (including Microsquirt and MS3-based units). This may not apply to plug-and-play units so refer to your vendor if that's what you have. Read through this completely a few times before starting the actual testing so that you know what you'll be doing and how to proceed with your specific setup. Refer to the manual on msextra.com for your specific unit or your vendor documentation, if needed, to perform the tasks mentioned below if you're not familiar with how these are done.

You will want to use a TunerStudio project specific to this test so you will need to create a new project with all the default settings for your unit. Also, make sure to save your settings (msq file) if you have started to enter settings specific to your installation or if your unit came with some setup-specific settings.

Initial settings

The first thing you will do is to check that you have a good primary (crank) tach signal and that you get an RPM reading. Since the MS2/Extra and MS3 firmware come with a 36-1 default setting, that is what is going to be used. That will get you a known good setup. Either start from a fresh load of the firmware on your ECU or load the default configuration (msq file) for your unit; don't change any of the settings. This will give you a setup that will work with a 36-1 crank wheel.

On the JimStim, set the wheel mode for a 36-1: set the DIP switch #3 to "ON" and all the other switches to "OFF". Set the primary tach signal jumper to the square wave position. If your ECU was built with a pull up resistor on the primary tach input, do not use another jumper. If your ECU does not have a pull up, set the pull up jumper for the primary tach to the 5V position.

Hall

If you have a V3.0 or V3.57 main board and are using the universal (VR) tach input circuit, set the trim pots for a Hall sensor: turn both pots fully counterclockwise and then turn R56 6 turns clockwise. If you are using a jbperf dual VR board V2.1 or have a Microsquirt V3.0 or MS3Pro, connect the primary tach to VR+ but leave VR- unconnected (floating). Other circuits used for a Hall sensors should work; refer to documentation or vendors since this out of scope of the present post. If you are using another VR circuit that requires a zero-crossing signal such as the LM1815 of the Microsquirt V2 or the Microsquirt module, skip further down this post.

With the default configuration on the ECU and the 36-1 configuration on the JimStim, you are ready to start the test. Open your TunerStudio project and turn on the unit. You should simply have to turn the RPM pots on the JimStim and see RPM reported on the TunerStudio dash. If that's not the case, the first thing to do is to check that the JimStim is working as intended: perform the tests described here. If the tests are successful, you will need to troubleshoot the MS circuit. The troubleshooting details are out of scope of this post so refer to documentation or vendors or post on the appropriate forum: the jbperf forum for JimStim issues and the msextra forum for MS issues.

VR

Once you know that you have a basically functional setup, you may want to go further. If your setup will use a VR primary tach sensor and you want to test this configuration on the bench or if you use an input circuit that requires a zero-crossing signal, you will need to change a few things to perform this initial test. The MS hardware and settings will remain as mentioned above. On the JimStim, you will need to set the primary tach signal jumper to the VR emulation position. You will also need to set the pull up jumper for the primary tach to the 12V position.

If you have a V3.0 or V3.57 main board, you will need to set both trim pots to the fully counterclockwise position. If the input circuit you use has a VR- input, connect it to ground since the JimStim does not generate a specific VR- signal.

You can now perform the test as described in the previous section. If successful, you can proceed with your testing. If not, you will need to troubleshoot your setup as described in the previous section.

Secondary tach (cam) / Hall

If your setup has secondary tach input (cam), you again will need to do a basic test to validate that you have a working setup. You will need to change one setting on the MS so that it can see and use the cam signal. You will go to the ignition options/wheel decoder screen and change the trigger wheel arrangement from "Single wheel with missing tooth" to "Dual wheel with missing tooth". That's it; do not change anything else. The only exception is if you have an MS3/MS3X setup and you are not using the MS3X cam input; you will then need to set the correct cam input.

There are many different setups used for the secondary tach input. If you're using an MS2 or an MS3 without the MS3X, connect the 2nd trigger header pin to the appropriate pin on the 19-pin header corresponding to the spare pin you used on the DB37 connector or to the pin you use on another connector. If you are using and MS3X, connect the signal to the MS3X DB37 (pin 32) or to the JimStimX cam header pin. If you are using another MS version, connect the 2nd trigger signal to the appropriate location; consult your unit documentation or your vendor.

On the JimStim, you will need to set the pull up jumper for the secondary tach to the 5V position. If there is any adjustment available on the circuit you are using, adjust them as per the Hall sensor settings. If you are using an input circuit that has a VR- input (dual VR board v2.1, Microsquirt V3, MS3Pro), leave it unconnected (floating). If you are using a VR circuit that require a zero-crossing signal (LM1815), skip further down this post.

With the single change to your MS ignition settings and with the connection as described above, you are ready to run the test with the primary and secondary tach signals. Open your test TunerStudio project and turn on your setup. You should see an RPM begin reported by TunerStudio when you turn the RPM pots on the JimStim. Make sure you get a full sync and not just a half sync. Also, you will want to check the composite log to see that you are getting a crank and a cam signal. Check your MS documentation to learn how to check those.

If you get the expected result, you know that you have a fully functional setup that gets both tach signal. If you are using a Hall or optical sensor as your secondary tach input, you are now ready to proceed with your bench testing and to use the actual settings you'll be using. Any issue related to RPM you have will be either a configuration issue or a mismatch between your MS settings and your JimStim settings. If you can't get a functional secondary trigger, you will need to troubleshoot your MS circuit since you should already have validated that the JimStim is fully functional. Consult your documentation, your vendor or the msextra forum to see how to proceed.

Secondary tach (cam) / VR

If you will use a VR sensor as you secondary tach input and you want to do your bench testing set for that or if you have an input circuit that requires it (LM1815), your will need to change the way you connect you 2nd trigger signal. The JimStim doesn't come with a VR emulation option on the 2nd trigger as it does with the primary one. To do the equivalent of this, you will need to add a capacitor in series with the signal. One way to do this in a quick and reversible way is to use 2 wire jumpers and a capacitor (the value is not critical but a 0.1uF ceramic capacitor can be used). The picture below shows how this can be done.
inline_cap_small.jpg
Series capacitor with wire jumpers
inline_cap_small.jpg (20.61 KiB) Viewed 5372 times

You simply put one lead of the capacitor in one end of a wire jumper and the other lead in one end of the other wire jumper (upper left on the picture above). You may need to put a small bend in the length of lead that goes inside the connector to make sure you have a solid connection. Then the free end of one wire jumper goes to the 2nd trigger header pin and the other free end goes to the MS secondary tach input as described in the previous section. You will also need to set the pull up jumper for the secondary tach to the 12V position.

Once those configuration changes are made, you can now perform the test described in the previous section. If successful, you can proceed with your testing using your own settings. If not, you will need to troubleshoot your setup as described in the previous section.

Jean
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jbelanger
 
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