Software and Testing

Now it's time to load the software on your computer. I recommend diyautotune's tuning software package. http://www.diyautotune.com/softwarelinks.htm The software from diyautotune is already configured. Simply install the software and run Megatune. The first dialog box that pops up asks which code we have installed. Select MS2-MicroSquirt BG 2.890.

Go into the "Communications" window and select the proper COM port (the "Verify ECU operation" does not operate, so do not be fooled). Exit this screen.

Plug the stimulator into the ECU. On the PC using MegaTune, click the "Realtime Display" under "Tuning" on the main menu, which brings up a new screen. (Note that if you have MS-II 2.8+ code, you may have to set the 'ECU Type' under 'Fuel Set-Up/General' otherwise all other menu items may be 'greyed out'.) Look at the "Time(s)" near the top left corner of the Realtime Display - it should be counting up, incrementing every second (it will roll over at the value of 255, back to zero). If the seconds count is there, you are running! If not, check the cable, make sure there is power, and check the COM port. The only other value on the screen which is working correctly is the "Batt V" box - it should be displaying the battery voltage (from about 7.0 - 8.5 volts, depending on the 9-volt battery condition). All other boxes will have nonsense for numbers.

Inputs

Remove the processor from the 40-pin socket - use a thin screwdriver and pry it from the socket, first one end, then the other - place it back on the foam pad it was shipped with. Now, you are going to install all of the input sensor components.

Install and solder C3 {399-4329-ND, 0.1 µF, 104 marking}. This is located in the bottom right section of the board (near the DB37, furthest away from the heat sink) between the U2 column of holes and the SPR2(CANL)/SPR1(CANH) holes.

Install and solder C2, C9 and C10 {399-2083-ND or 399-4353-ND, 0.22 µF, 224 marking}. These install in the column of capacitors just above "Grippo" in the copyright notice on the silkscreen at the bottom of the board.

Install and solder C4, C6, and C8 {399-4202-ND, 0.001 µF, 102 marking}. These install in the column of capacitors just above "Grippo" in the copyright notice on the silkscreen at the bottom of the board.

Install and solder C5 and C7 {399-2102-ND or 399-4389-ND, 1.0 µF, 105 marking}. These install in the column of capacitors just above "Grippo" in the copyright notice on the silkscreen at the bottom of the board.

Install and solder R2, R9, and R10 {1.0KQBK-ND, 1K, brown-black-red}. These install in the column of resistors just above "&" in the copyright notice on the silkscreen at the bottom of the board.

Install and solder R5 and R8 {2.2KQBK-ND, 2.2K, red-red-red}. These install in the column of resistors just above "&" in the copyright notice on the silkscreen at the bottom of the board.

Install and solder R11 {1.0MEBK-ND, 1M, brown-black-green-gold). This installs in the column of resistors just above "&" in the copyright notice on the silkscreen at the bottom of the board.

Next is the Hall/Optical input circuit.

1. Install and solder R12 {390H-ND, 390 Ohm, ½ watt, orange-white-brown}. This is installed between the resistors you have just been installing and the CPU socket. This resistor should be mounted roughly 1/8" (2mm) above the surface of the PCB.
2. Install and solder R13 {4.7KEBK-ND, 4.7k, yellow-violet-red}. This is located 3 places close to the heat sink than R12 (which you just installed).
3. Install and solder C11 {399-2075-ND or 399-4326-ND, 0.01µF, 103 marking}. This installs at the top of the row of 'vertically' oriented capacitors above "Bowling" in the copyright notice.
4. Leave the C30 location empty - DO NOT jumper it.
5. Do not install D1, put a jumper in its place. It is located beside R12, further from the heat sink.
6. Do not install D2, install a jumper (made from a snipped off lead) in its place. It is located beside D1, closer to the heat sink.
7. Install/solder opto-isolator U3 {160-1300-5-ND, 4N25). This is located near the center of the PCB. Observe the proper orientation (notch matches PCB - towards the heat sink, or dot for pin #1 which is the square pad on PCB at the notched end of the silk screen). If neither are there, hold the chip so that the writing is facing you and the right way around. Pin #1 is on the bottom left.
8. Leave the C12 location empty - DO NOT jumper it. This is located above "Bowling" in the copyright notice.

Next install jumpers:

• Jumper XG1 to XG2 on the bottom side of the PCB, near the 40 pin socket,
• Jumper OPTOIN to TACHSELECT on the bottom side of the PCB, near the DB37 connector, opposite the heat sink.
• Jumper TSEL to OPTOOUT on the bottom side of the PCB, near the center.

Time to install the onboard MAP sensor. It mounts on the under side of the PCB, with the vacuum port facing the DB37 connector end of the PCB, and the markings on the sensor facing away from the PCB so you should be able to read the "MPX4250AP" marking when the sensor is installed. The leads are bent toward the PCB, and soldered on the top-side. The notch on the lead indicates pin #1 - this corresponds to the square pad on the PCB.

The MAP sensor is held to the PCB with two nylon screws - do not tighten the MAP sensor too tight, this will distort the case and introduce an offset in the readings by flexing the load cell inside the device. And, yes, solder the leads on the top side of the PCB. You will have to devise a scheme to run a tube from the barbed MAP fitting to your intake manifold.

Install and solder R4 and R7 {2.49KXBK-ND, 2.49K, red-yellow-white-brown-brown). These are the temperature sensor "bias" resistors. They install above the "&" in the copyright notice.

Testing inputs is important to make sure you built everything correctly. Directions for testing can be found on the megamanual V3.0 assembly instructions - Step 55.


Outputs

Install and solder R14 and R17 {10KEBK-ND, 10K Ohm, brown-black-orange). These are located near the center of the PCB, in the column of components roughly aligned with Q9 on the heat sink.

Install and solder R16, R19, R26, R27, and R29 {1.0KEBK-ND, 1K Ohm, brown-black-red}. R16 is near the MOV1 (but a bit further away from the DB37 connector). R19 is to the right (closer to the DB37 connector) of the resistors you installed in the last step (R14 & R17) on the other side of C13 and C14. R26, R27, & R29 are located near the LEDs at the DB9 end of the PCB.

Install and solder D3 {1N4001DICT-ND}. This is located near the center of the PCB, near R14 and R17. Observe the proper polarity.

Install and Solder D4 and D8 {1N4748ADICT-ND} - observe the proper polarity. These are located beside MOV1, a bit further away from the DB37 connector.

Install and solder R15 and R20 {22QBK-ND, 22 Ohm, red-red-black}. R15 is located below the Q1 location on the heat sink, R20 is located below the R38 location on the heat sink.

Install and solder R24, R25, and R28 {330QBK-ND, 330 Ohm, orange-orange-brown). These are located very near the LEDs on the DB9 end of the PCB.

Install and solder the transistors Q2 and Q4 {ZTX450-ND}. These are located to the left of the MOV1. The side of the transistor with the white label faces the DB37 connector. If you got this transistor from a distributor (as part of a kit) then they likely have special instructions for it (search the packaging or contact the distributor). Distributors sometimes make substitutions for various reasons, and thus their notes are important. If your Q2/Q4 are the standard Digi-Key part {ZTX450-ND}, but don't have a white label, then the side with the rounded edges is the 'curved side', which is oriented to be closest to the DB37 connector.

Install C13 {399-4329-ND, 0.1 µF, 104) - and solder. This is located a bit closer to the heat sink, and a bit closer to the DB9 than Q4.

Install and solder C14 {399-3559-ND, 4.7 µF). This is located just a bit further away from the heat sink than C13, which you installed in the last step. Observe polarity. Recall that the positive lead has a small + near it on the body of the capacitor.

Install and solder U4 {IXDI404PI-ND}, the FET driver. This is located near the Q3 location on the heat sink. If you bought a socket {AE7208-ND}, solder it in place and insert the chip. Be sure to orient it correctly, the notch or dot on the chip goes to the notched end on the silkscreen; this end is closest the heat sink.

Install D17 and D18 {1N5819DICT-ND}, the Schottky diodes. These are located on either side of the FET driver (U4) you just installed. Make sure the band on the diode matches the silkscreen.

Install and solder D21 {1N4753ADICT-ND}. This is located just a bit further away from the heat sink than D17. Make sure the band on the diode matches the silkscreen.

The following are directions for installing the PWM flyback dampening circuit. This will allow you to run either high or low impendence injectors.
Install R30, R31, R34 and R35 {270QBK-ND, red-violet-brown}. R30 and R31 are near R37 on the heat sink, R34 and R35 are near Q9.

Install R32 and R36 {1.0KQBK-ND, 1K Ohm, brown-black-red}. These are located besides the resistors you installed in the last step.

Install Q9 and Q12 {TIP125TU-ND}. Bend the leads to fit in the holes so that the hole in the tab lines up with the hole in the heat sink. These transistors mount to the heat sink, but they MUST have an insulator between the transistors and the heat sink. Use the insulator kits for this {4724K-ND}. You may have to trim the mica insulator somewhat to avoid hitting the transistor leads - use a sharp pair of scissors. Use heat transfer compound between the component, mica insulator, and the heat sink.

Install Q10 and Q13 {2N3904FS-ND}. The flat side of the transistors face the heat sink. These are located near Q9 and R37 on the heat sink. The pins are very close together, use a clean tip, and be careful not to bridge the joints.

Then install the standard flyback circuit
Install R18 and R33 {270QBK-ND, red-violet-brown}. These are located below R38 and Q1 on the heat sink.

Install D6 and D20 {1N4753ADICT-ND}. These are located beside the resistors (R18, R33) you just installed. Make sure the band on the diode matches the silkscreen.

Install Q3 and Q11 {497-2629-5-ND}. These mount to the heat sink. No insulator kit is necessary, the tab can contact the heat sink. Use heat transfer compound between the component and the heat sink.

Now install the current limiting circuit
Install R37 {TAH20PR050JE-ND}. It goes on the heat sink, however it does not have a mounting hole. You can use double sided thermal transfer tape {BER158-ND} to fasten it to the heat sink, however this is quite expensive if you are just doing two resistors.

Install R38 {TAH20PR050JE-ND}. It goes on the heat sink as well, however it does not have a mounting hole. You can use double sided thermal transfer tape {BER158-ND} to fasten it to the heat sink, however this is quite expensive if you are just doing two resistors.

Then install Q14 and Q15.

Install D5 and D7 {FR302DICT-ND}. These diodes should be mounted about 1/8" to 1/16" off the board. Make sure the band on the diode matches the silkscreen. These are located near R38 and Q3.

Install Q19 and Q20 {2N3904FS-ND}. These are located in line with the existing transistors (Q2 and Q4) to the left of the MOV1. Be very careful when soldering them, use a clean tip, as the pin spacing is very tight.

Install R39 and R40 {1.0H-ND, 1 Ohm, brown-black-gold}. These are located on either side of the transistors (Q19 & Q20) that you installed in the last step.

Install Q1 and Q5 {IRFIZ34GPBF-ND}, the FETs (field effect transistors, used to drive the injectors). These are bolted to the heat sink, be sure to use heat transfer compound between the FET and the heat sink. These are insulated case variety, so they mount directly on the heat sink.

Install and solder Q6, Q7, and Q8 {2N3904FS-ND}. Follow the silkscreen to orient the flat side of these transistors, which faces the DB9 end of the PCB.

Now assemble the case and mount the LEDs - D14, D15, and D16 {P301-ND} to the case font, and bend the leads down to the board and solder. The flats on the LEDs (the side with the short lead) faces the DB9 connector. First, install the LED holders on the front panel, through the front. Next, the LEDs press into the rear of the holder. Mount the case front panel to the case half (which has the PCB). Orient the FLAT on the side of the LED lip (the side with the shorter lead) towards the DB-9 socket (each LED). You will see that the PCB silk screen also has a "dash" above the LED circle symbol indicating the side of the flat. Bend the LED leads down to enter the PCB holes for them - you will have to do a trial fit, then trim the leads down a bit. See the illustrations below. Then solder the LEDs to the PCB from the top of the PCB. It is a little tricky - take your time.

Your megasquirt is now completed.