This write up is for installing a Mega Squirt II using the MS2/Extra firmware (there are many versions of Mega Squirt so be sure to pay attention) on a 2.4LD9 or any other earlier Quad 4, HO, LO, W41 families. Please forgive me I have not been on here in a while and I may have forgotten some things about j-bodies but I should be able to recall quickly if asked or with little refreshing. I felt that I owed it to all of you being that I have played with this engine for 15 years. This install will need to use an Ignition Control Module from an OBD I General Motors 4 cylinder such as a 94 Saturn or similar (easy to find in your local pick and pull junk yard for 20 bucks). This will make the engine run as a batch fire injection strategy (instead of the factory sequential injection strategy and will remain a wasted spark ignition configuration and will not need to use the stock cam position sensor. Yes this means you can run the HO cam swap with out having issues other than the power steering, but who needs power steering when you are racing haha)
This Mega Squirt II is a stand alone Engine Control Unit. It will not interface with stock gauges or Body Control Modules. Someone can try that out if they wish to piggy back the stock instrument cluster. I am sure there is a way to do it. I went with more of a complete custom installation and used aftermarket gauges.
Please read and understand the Mega Squirt II manual and configuration documents prior to attempting any Mega Squirt installation. This is not the one safe source every thing to know about Mega Squirt. There are several pages of documentation for the Mega Squirt. This is simply the key topics in Mega Squirting the engines mentioned above.
I will be happy to make this a working document. Mega Squirt is continuously evolving tuner power tool. New things will come up and be offered with code development. Forgive me ahead of time I’m not on here regularly anymore.
WARNING. If you do not understand engines, and engine tuning principals you can destroy your engine and or Mega Squirt with 1 key stroke.
ATTENTION It is important to know what code you are running and when using the support forums to mention it in your post if you have questions. There are several code versions floating around and some early versions may have a feature flip flopped (such as the Idle Air Contorl stepper motor map for example).
This is the main index. Very helpful
This is the main Document for the MSII, but the index site above has this info and I think is more up to date
This is the shop that sells all the Mega Squirt goodies and has the latest Code down loads.
Abbreviations that will be used in this write up
ECU – Engine Control Unit
MSII- Mega Squirt II
Ms – Milliseconds
MSQ- The flash file for your vehicle (tune)
ICM- Ignition Control Module
VE- Volumetric Efficiency
First of all this example install is on MS2/extra firmware and is for a built 2.4L using 4, 1000 cc Low impedance injectors running a modified fuel pressure so the injector constants will be different than most other cars, but this is easy to overcome with changing some variables in the settings using the Tuner Studio software on you PC/ computer. This is why you will need to know every thing about your engine and hardware. This will make sense once you read the documents I suggested earlier. All other settings will be the same other than the VE table and injector constants/ settings.
Study and wire up you engine like the main engine harness/ MSII harness wire diagram
Wire up your electric fan to the fast idle wire. This is a programmable out put and you will configure it to run your fan at the temp you set it to.
Wire up your ICM as displayed in this image
You will need to wire up the GM HEI by pass relay as shown here
To use the GM DIS module, build your MegaSquirt® as shown in the GM HEI section. To connect the module to MegaSquirt:
Module pin B or C - white wire - DB37 #36 (V3 main board, ignition output signal pin for V2.2),
Module pin A - tan/black wire - Connect to a bypass relay as shown for the HEI modules,
Module pin E - purple/white wire - DB37 pin #24 (tach),
Module pin F - red/black wire - ground,
Module separate connector - black/white - ground,
The module also has connections for power (pink), the crank position sensor (yellow & purple), and tach (white).
Once you are wired up and powered on you will need to load your code/ firmware, if you have not already. Download the code from http://www.diyautotune.com/
Use these instructions for loading firmware scroll down to the MS2/extra section http://www.msextra.com/doc/ms2extra/upgrade.html
Next you will need to calibrate you throttle position sensor, under tools, calibrate TPS. Follow instructions on screen
Next select the wide band you are using, under tools, calibrate AFR table
Follow instructions on screen
Next you will configure you MSQ file/ tune
Use the pictures below
These are all the settings under the basic set up tab in tuner studio. You will need to hit the required fuel button on the standard injection menu with you engine and injector specifics. Pay close attention to the Ignition Options window (not the More Ignition Options window) This is how to set up the trigger using the the OBD 1 ICM. Zoom in on these pictures so you can see every thing.
This is the Spark Advance map that has worked really well for me. It is conservative. Going too aggressive here can destroy your engine so be careful.
VE table this will be different on every set up depending on the engine build, cams, turbo, injector size and fuel pressure.