Get your 86-93 Fox Body Mustang up and running in minutes!

Using the MegaSquirt-I (MSnS-E) with a MSD 6A Ignition Box on a TFI Vehicle

(such as the 86-95 Mustang)

This setup drives the MSD box through a BIP373 transistor (for a V3.0 board) or 2N2222A (for a V2.2) and works with the stock Ford fast idle valve. The V3.0 version can also drive a coil directly.

MegaSquirt-I PCBv2.2 Mods Required: 

• Input mod:  You install a 1k 1/4w resistor in place of D8
• Output mod: Run a jumper wire from the negative lead of LED 17 to jumper X11.
• Fast idle mod: Replace transistor Q5 with a TIP120/121/122 power Darlington, as shown on our MK-PWMIAC catalog page.
• That's it!

MegaSquirt-I PCBv3.0 Mods Required: 

• Input mod:  You install a 1k 1/4w resistor in place of D2. Jumper TachSelect to OptoIn, XG1 to XG2, and TSEL to OptoOut.
• Output mods:
• Jumper IGBTOUT to IGN to send to IGBT ignition coil driver signal out of pin 36 on the DB37.
• Install Q16 if it is not already installed (Our units will have this already soldered in).
• Cut out R57 if fitted (This won't be there on my units, though).
• Get a 330 ohm 1/4w resistor and cut the leads down to about 1/2" at each end. Maybe a bit less.
• Tin each end of the resistor with a bit of solder.
• Cut a 5" piece of hookup wire (22ga is fine) and strip just a 1/8" or so. Tin the stripped wire with solder.
• Melt the tinned wire tip to one end of the tinned 330 ohm resistor tip and let it cool.

• Heatshrink wrap this wire/resistor assembly.

• Use this wire/resistor combo to jumper the 'top' (top as in when you facing the silkscreen side of the PCB, with the text so that you can read it normally) lead of R26 to IGBTIN on the opposite side of the PCB.

• Fast idle mods:
• Remove Q20 and D8.
• Remove R39 and install a jumper in its place.
• Install a TIP120/121/122 in place of Q4. For more information, see our MK-PWMIAC page.
• That's it!

MSnS-E Ignition Configuration

• Configur MegaTune for MSnS (NOT TFI) Spark Output using LED17 (D14).   (You'd only set it to TFI if you weren't using the MSD box and had done the TFI mods)

• In MegaTune, you MUST have "spark output" set to "inverted." 
• The MSD box will control the dwell.

External Wiring

Here is an external wiring diagram for the V3.0 board. V2.2 wiring is identical except that you will connect the MSD white wire to pin 25 instead of 36. Note that the fuses and relays are already in the stock wiring, so you will not need to change these. The injector configuration shown is intended to promote smooth flow through the fuel rails and is one of several possible ways to wire the injectors.

Using the MegaSquirt-I (MSnS-E) with the factory TFI Ignition

(such as the 86-95 Mustang)

MegaSquirt-I PCBv2.2 Mods Required: 

• Input mod:  You install a 1k 1/4w resistor in place of D8
• Output mods:
• Run a jumper wire from the negative lead of LED 17 to jumper X11.
• Get a 1k ohm 1/4w resistor and cut the leads down to about 1/2" at each end. Maybe a bit less.
• Tin each end of the resistor with a bit of solder.
• Cut a 5" piece of hookup wire (22ga is fine) and strip just a 1/8" or so. Tin the stripped wire with solder.
• Melt the tinned wire tip to one end of the tinned 330 ohm resistor tip and let it cool.

• Heatshrink wrap this wire/resistor assembly.

• Use this wire/resistor combo to jumper the negative lead of LED17 to the left pin of U5 to add a 12 volt pull-up.
• Fast idle mod: Replace transistor Q5 with a TIP120/121/122 power Darlington, as shown on our MK-PWMIAC catalog page.
• That's it!

MegaSquirt-I PCBv3.0 Mods Required: 

• Input mod:  You install a 1k 1/4w resistor in place of D2. Jumper TachSelect to OptoIn, XG1 to XG2, and TSEL to OptoOut.
• Output mods:
• Run a jumper wire from the lead of D14 nearest the DB9 connector to the IGN jumper.
• Wrap a 1k resistor in a length of heat shrink tubing, about 1" long, so that the leads of the resistor stick out both ends of the tubing.
• Use this insulated resistor to connect the S12 jumper hole to the IGN jumper to provide a 12 volt pull-up on the ignition output.
• Fast idle mods:
• Remove Q20 and D8.
• Remove R39 and install a jumper in its place.
• Install a TIP120/121/122 in place of Q4. For more information, see our MK-PWMIAC page.
• That's it!

MSnS-E Ignition Configuration

• Configure MegaTune for TFI Spark Output using LED17 (D14). 

• Set Spark Output Inverted to Yes.
• Set Trigger Angle to 10 degrees.
• Set Dwell to Fixed Duty, and Spark Output Duty Cycle to 50% duty cycle. 

External Wiring

Here is an external wiring diagram for the V3.0 board. V2.2 wiring is identical except that you will connect the TFI SPOUT signal to pin 25 instead of 36. Note that the fuses and relays are already in the stock wiring, so you will not need to change these. The injector configuration shown is intended to promote smooth flow through the fuel rails and is one of several possible ways to wire the injectors.

Using the MegaSquirt-I (MSnS-E) with a MSD 6A Ignition Box on a TFI Vehicle

using the Fast Idle Output for spark control

This is an older setup that is somewhat easier to build, but does not offer fast idle support, nor does it use quite as reliable a transistor to drive the MSD box as the BIP373.

MegaSquirt-I PCBv2.2 Mods Required: 

• Input Mod:  You install a 1k 1/4w resistor in place of D8
• Output Mod: None Required when using MSD 6a Box.

MegaSquirt-I PCBv3.0 Mods Required: 

• Input Mod:  You install a 1k 1/4w resistor in place of D2
• Output Mod: None Required when using MSD 6a Box.

MSnS-E Ignition Config

• Configured for MSnS (NOT TFI) Spark Output using FIDLE (pin 30)   (You'd only set it to TFI if you weren't using the MSD box and had done the TFI mods)

             <--- Click here for a closer look at the proper settings

• In MegaTune, you MUST have "spark output" set to "inverted." 

Thanks to 'stangdrvr' for the drawings and notes and permission to use them here!

These diagrams are very useful if you are planning on running your MegaSquirt using a MSD 6a box to provide the ignition signal.

There are a few changes to the second diagram as compared to the MegaManual on the msefi site.  These changes are TFI + MSD specific.

A1 = Connect to oxygen sensor, LM-1, or LC-1 output.
B2 = Connect to blue wire from TFI module.
C3 = Connect to coil outputs from MSD.
D4 = Connect to white wire from MSD.

Using the MegaSquirt-II PCBv3 with the factory TFI Ignition

(such as the 86-95 Mustang)

If you're assembling your MegaSquirt-II from a kit (Part# MS230-K):

• For the most part, stick with the standard assembly documentation at http://www.megamanual.com/ms2/V3assemble.htm.  I'll just be covering any differentiation from that doc here.

• Step 22:  You really don't need any of the 5 jumper wires listed in this step.  If you ever use this ECU on a different car that does use a stepper motor IAC you can add them then.  Personally, I'd leave them out for your Mustang as you can use the IAC outputs for other cool stuff later.

• Step 50:  You'll be installing the 'Hall/Optical Input Circuit'  (currently all steps under 50a).  If you see any steps that say 'only do this if you are triggering from the negative terminal of the coil', you aren't, so don't. ;)

  • INSTEAD OF JUMPERING D2 as directed here, install a 1k 1/4watt resistor in it's place.

• Step 51:  You don't need these components, but I'd recommend installing them anyways in case the MS ECU is ever used on another car with a VR sensor.

• Step 52:  Set the jumpers for Hall/Optical/Points.  That would be XG1 to XG2, OPTOIN to TACHSELECT, and TSEL to OPTOOUT.

• Step 59:  You will be doing the PWM Idle Mod using the parts from the mk-PWMIAC.  That means you leave D8 out when you get to this step.

• Step 62:  Follow the steps in the blue box following step 62 to finish installing the mk-PWMIAC for control of your 2-wire idle valve.

• Step 65:  You ARE USING THE IGBT High Current Ignition Driver Circuit.  That means you complete step 65.  Install everything just as this step directs you to (which does mean no R57), and install the jumpers to enable the circuit. (IGBTIN to JS10 and IGBTOUT to IGN) Note that if you are using a metal backed transistor like a BIP373 or certain switching transistors, you must use a mica insulator under Q16.

NOTE-- there was originally an error in the MS2 TFI docs that said to leave R43 out for this setup, I've found that to be incorrect and it's been corrected it in the MS2 docs, so LEAVE R43 in!

• Step 69:  Choice time -- Install the PWM Flyback Circuit bits....

• Step 71:  Choice time -- Install the  current limit circuit for FET protection....

• Step 74:  Do not install Q20 (part of the mk-PWMIAC mod)

• Step 75:  Leave R39 out and jumper it instead (part of the mk-PWMIAC mod)

• Now for the final step (Mod for TFI Ignition Output).  Use a 100ohm, 1/4watt resistor.  Solder one leg of this to the IGN/IGBTOUT jumper wire.  Solder the other leg of this to the hole labeled S12.  (Not to be confused with the hole labeled S12C !)  The S12 label is on TOP of the board, but you'll place this resistor on the bottom generally.  Check out this diagram.

  

  Image courtesy of Bowling and Grippo

   

That's it-- you've got your Megasquirt-II Engine Management System fully prepared to receive the ignition input from your TFI module, and return the Megasquirt controlled ignition output back to the TFI module giving you full control of your stock TFI ignition system.  At the same time you've also 'modded' the FIDLE output to be able to handle your Pulse-Width Modulated (PWM) Idle-Air-Controller (IAC). 

If you're modifying a DIYAutoTune.com MS230-C MegaSquirt-II Assembled ECU:

Input Mod:

• There will be a jumper wire in the D2 position.  Remove this jumper wire and place a 1k 1/4 watt resistor in this position instead.

Output Mod:

• There will be a jumper wire from JS10 over to IGN.  Desolder and remove this (don't just cut it, you'll need the holes clear of solder).
• Install new jumper wires to enable the IGBT High Current Ignition Driver Circuit (IGBTIN to JS10 and IGBTOUT to IGN)
• Use a 100ohm, 1/4watt resistor.  Solder one leg of this to the IGN/IGBTOUT jumper wire.  Solder the other leg of this to the hole labeled S12.  (Not to be confused with the hole labeled S12C !)  The S12 label is on TOP of the board, but you'll place this resistor on the bottom generally.  Check out this diagram.

Image courtesy of Bowling and Grippo

That's it-- you've got your Megasquirt-II Engine Management System fully prepared to receive the ignition input from your TFI module, and return the Megasquirt controlled ignition output back to the TFI module giving you full control of your stock TFI ignition system.  At the same time you've also 'modded' the FIDLE output to be able to handle your Pulse-Width Modulated (PWM) Idle-Air-Controller (IAC). 

Wiring it all up...

I couldn't possibly hope to cover all of the wiring information that is so thoroughly covered in the MegaManual here, and for the most part there's really no need to.  Sensors and Injectors wire up the same on most every vehicle out there... You can use the MegaManual's wiring section for this information.  I'm going to cover the Mustang specific stuff here.... that would be the Ignition Wiring and the PWM IAC valve wiring.  Those are the only two missing pieces of the puzzle.

Ignition Wiring:

• Input: Pin 24 on MS-II DB37, PIP from TFI module

• Output: Pin 36 on MS-II DB37, SPOUT to TFI module

Image courtesy of Bowling and Grippo

PWM IAC Wiring:

To wire this up without the relay board (directly to the ECU), wire up the hot wire from the idle valve to switched 12v+ (hot in RUN), and wire the negative wire from the idle valve directly to pin 30 on the MegaSquirt DB37.


To wire this up with the relay board, you will need to jumper the FIDLE relay to take it out of the loop, below is a picture of how to do this. Then you will still wire up the hot wire from the idle valve to switched 12v+ (you could use the fuel pump power from the relay board), and wire the negative wire from the idle valve directly to the FIDLE terminal on the relay board. This will allow full control of your PWM idle valve.

Image 'borrowed' from the MSnS-E pages

You should also put a 1N4001 diode across the PWM Idle valve itself - the banded end goes to the 12 Volt supply, the non-banded end goes to the lead that goes to MegaSquirt (this diode is for flyback purposes on the idle valve).

Megatune Ignition Configuration:

(from B&G's TFI Control page for the MS-II)

• Trigger offset = 10° (this will vary, depending on the distributor orientation, see below)
• Ignition Input Capture to 'Falling Edge'
• Cranking Trigger to 'Trigger Rise'
• Coil Charging Scheme to 'Standard Coil Charging'
• Spark Output to 'Going High (Inverted)'

Then set the dwell setting to 8.0 milliseconds with no battery voltage compensation. This will get the spark output to closely imitate the square wave signal that the EEC-IV computer sends out.

More information on setting Trigger Offset:

You must also set the initial position of the trigger (called the 'trigger offset'), then check it using the Trigger Wizard in MegaTune  (Tools Menu).  The trigger offset setting will vary according to your distributor position (where it is in rotation) but you'll need to set it properly...  Basically you use the Trigger Wizard and adjust the 'trigger offset' and/or twist your distributor until the advance number in the Trigger Wizard matches what you're reading with your timing light.  The +/- buttons on the trigger wizard will adjust your trigger offset.  You'll need to use these buttons and a timing light to make the number on your light, and the big number on the left in the Trigger Wizard, match up.

Here's the information on this direct from the MegaTune Manual:

Before tuning your advance table, be sure to use a timing light to verify that your 'trigger offset' is calibrated. Changing the Trigger Offset in MegaTune will not change the displayed advance, instead, it changes the actual advance as seen with a timing light. Your goal is to make these two match.

To do this, get your engine warmed-up (otherwise the timing moves as the temperature increases) and idling, then use a timing light to verify to be certain your actual advance as shown by a timing light equals your the advance display on the advance gauge in MegaTune. (8° in this case). (Note that positive numbers denote BTDC, and negative numbers denote after TDC.)

Image courtesy of Bowling and Grippo

Megatune PWM IAC Configuration:

• First open the MegaTune Configurator, and open CAR1>SETTINGS.INI>SETTINGS>IDLE_CONTROLLER and select PWM_GAUGE from the dropdown box at the top right.
• Save and exit the Configurator.
• Open MegaTune and connect to the ECU, and from the SETTINGS menu choose IDLE CONTROL.
• Select the PWM Warmup ‘Algorithm' and then you can configure the values for your vehicle and click ‘Burn to ECU'.
  

MS/2Extra settings for the IAC valve are found in the base map below.

Coolant (CLT) / Intake (IAT/MAT) Temperature Sensor Calibration

You can use your stock IAT and CLT sensors, and with the MegaSquirt-II you can calibrate these sensors through MegaTune.  It's best to leave the standard R4 and R7 'Bias Resistors' in place in the MegaSquirt and just configure this in the software.  You get better accuracy this way.

• Open MegaTune>Tools>Calibrate Thermistor Tables
• Select 'Coolant Temp Sensor', Select 'Fahrenheit', and enter these values:

• Click OK and the Coolant sensor will be calibrated.
• You're not quite finished yet though--- You need to repeat these steps, but choose 'Air Temperature' as the sensor table and use the same temp and resistance values from above as the sensors use the same curve.  This will calibrate the IAT as well.

NOTE-- Make sure you chose Fahrenheit or your readings will be WAY off with the above values....

More Information

• Everyone should thoroughly read the MegaManual.  I mean... you wouldn't buy a new doo-dad and install it without using the manual would you?  OK now seriously though... this is your pride and joy we're talking about here...  read the manual and the FAQ!!!   
  • Read both the MS1 and MS2 sections, not all of the MS1 section will apply to you, but MUCH of it will, and the MS2 section isn't really complete without this information.
• Another great resource I refer to often is the MegaTune Tuning Software Manual.

Using the MegaSquirt-II PCBv3 with a MSD 6A Ignition Box on a TFI Vehicle

(such as the 86-95 Mustang)

If you're assembling your MegaSquirt-II from a kit (Part# MS230-K):

• For the most part, stick with the standard assembly documentation at http://www.megamanual.com/ms2/V3assemble.htm.  I'll just be covering any differentiation from that doc here.

• Step 22:  You really don't need any of the 5 jumper wires listed in this step.  If you ever use this ECU on a different car that does use a stepper motor IAC you can add them then.  Personally, I'd leave them out for your Mustang as you can use the IAC outputs for other cool stuff later.

• Step 50:  You'll be installing the 'Hall/Optical Input Circuit'  (currently all steps under 50a).  If you see any steps that say 'only do this if you are triggering from the negative terminal of the coil', you aren't, so don't. ;)

  • INSTEAD OF JUMPERING D2 as directed here, install a 1k 1/4watt resistor in it's place.

• Step 51:  You don't need these components, but I'd recommend installing them anyways in case the MS ECU is ever used on another car with a VR sensor.

• Step 52:  Set the jumpers for Hall/Optical/Points.  That would be XG1 to XG2, OPTOIN to TACHSELECT, and TSEL to OPTOOUT.

• Step 59:  You will be doing the PWM Idle Mod using the parts from the mk-PWMIAC.  That means you leave D8 out when you get to this step.
• Step 62:  Follow the steps in the blue box following step 62 to finish installing the mk-PWMIAC for control of your 2-wire idle valve.
• Step 65:  You ARE USING THE IGBT High Current Ignition Driver Circuit.  That means you complete step 65.  Install everything just as this step directs you to (which does mean no R57), and install the jumpers to enable the circuit. (IGBTIN to JS10 and IGBTOUT to IGN) Note that if using a metal backed transistor like a BIP373, you must use a mica insulator under Q16.

NOTE-- there was originally an error in the MS2 TFI docs that said to leave R43 out for this setup, I've found that to be incorrect and it's been corrected it in the MS2 docs, so LEAVE R43 in!

• Step 69:  Choice time -- Install the PWM Flyback Circuit bits....
• Step 71:  Choice time -- Install the  current limit circuit for FET protection....
• Step 74:  Do not install Q20 (part of the mk-PWMIAC mod)
• Step 75:  Leave R39 out and jumper it instead (part of the mk-PWMIAC mod)

That's it-- you've got your Megasquirt-II Engine Management System fully prepared to receive the ignition input from your TFI module, and return the Megasquirt controlled ignition output out to your MSD 6a CD Ignition box-- Giving you full control of your fuel and ignition!.  At the same time you've also 'modded' the FIDLE output to be able to handle your Pulse-Width Modulated (PWM) Idle-Air-Controller (IAC). 

If you're Modifying a DIYAutoTune.com MS230-C MegaSquirt-II Assembled ECU:

Input Mod:

• There will be a jumper wire in the D2 position.  Remove this jumper wire and place a 1k 1/4 watt resistor in this position instead.

Output Mod:

• There will be a jumper wire from JS10 over to IGN.  Desolder and remove this (don't just cut it, you'll need the holes clear of solder).
• Install new jumper wires to enable the IGBT High Current Ignition Driver Circuit (IGBTIN to JS10 and IGBTOUT to IGN)

That's it-- you've got your Megasquirt-II Engine Management System fully prepared to receive the ignition input from your TFI module, and return the Megasquirt controlled ignition output out to your MSD 6a CD Ignition box-- Giving you full control of your fuel and ignition!.  At the same time you've also 'modded' the FIDLE output to be able to handle your Pulse-Width Modulated (PWM) Idle-Air-Controller (IAC).

Wiring it all up...

I couldn't possibly hope to cover all of the wiring information that is so thoroughly covered in the MegaManual here, and for the most part there's really no need to.  Sensors and Injectors wire up the same on most every vehicle out there... You can use the MegaManual's wiring section for this information.  I'm going to cover the Mustang specific stuff here.... that would be the Ignition Wiring and the PWM IAC valve wiring.  Those are the only two missing pieces of the puzzle.

Ignition Wiring:

• Input: Pin 24 on MS-II DB37, PIP from TFI module

• Output: Pin 36 on MS-II DB37, connected to white wire (points trigger) on the MSD 6a box

Image courtesy of Bowling and Grippo

PWM IAC Wiring:

To wire this up without the relay board (directly to the ECU), wire up the hot wire from the idle valve to switched 12v+ (hot in RUN), and wire the negative wire from the idle valve directly to pin 30 on the MegaSquirt DB37.


To wire this up with the relay board, you will need to jumper the FIDLE relay to take it out of the loop, below is a picture of how to do this. Then you will still wire up the hot wire from the idle valve to switched 12v+ (you could use the fuel pump power from the relay board), and wire the negative wire from the idle valve directly to the FIDLE terminal on the relay board. This will allow full control of your PWM idle valve.

Image 'borrowed' from the MSnS-E pages

You should also put a 1N4001 diode across the PWM Idle valve itself - the banded end goes to the 12 Volt supply, the non-banded end goes to the lead that goes to MegaSquirt (this diode is for flyback purposes on the idle valve).

Megatune Ignition Configuration:

(from B&G's MSD 6a Control page for the MS-II)

• Ignition Input Capture to 'Rising Edge'
• Cranking Trigger to 'Trigger Rise'
• Coil Charging Scheme to 'Standard Coil Charging'
• Spark Output to 'Going Low (Normal)'
• Maximum Spark Duration to '25.5'

Under the dwell settings:

• Maximum Dwell Duration to '25.5'

To set the dwell to 25.5, you'll have to change one of lines in the megasquirt-II.ini file.  You'll find this file in C:\Program Files\MegaSquirt\MegaTune2.25\mtcfg

Edit the following line: (use CTRL-F to search for max_coil_dur to find the line)

to

You must also set the initial position of the trigger (called the 'trigger offset'), then check it using the Trigger Wizard in MegaTune  (Tools Menu).  The trigger offset setting will vary according to your distributor position (where it is in rotation) but you'll need to set it properly...  Basically you use the Trigger Wizard and adjust the 'trigger offset' and/or twist your distributor until the advance number in the Trigger Wizard matches what you're reading with your timing light.  The +/- buttons on the trigger wizard will adjust your trigger offset.  You'll need to use these buttons and a timing light to make the number on your light, and the big number on the left in the Trigger Wizard, match up.

Here's the information on this direct from the MegaTune Manual:

Before tuning your advance table, be sure to use a timing light to verify that your 'trigger offset' is calibrated. Changing the Trigger Offset in MegaTune will not change the displayed advance, instead, it changes the actual advance as seen with a timing light. Your goal is to make these two match.

To do this, get your engine warmed-up (otherwise the timing moves as the temperature increases) and idling, then use a timing light to verify to be certain your actual advance as shown by a timing light equals your the advance display on the advance gauge in MegaTune. (8° in this case). (Note that positive numbers denote BTDC, and negative numbers denote after TDC.)

Image Courtesy of Bowling and Grippo

Megatune PWM IAC Configuration:

• First open the MegaTune Configurator, and open CAR1>SETTINGS.INI>SETTINGS>IDLE_CONTROLLER and select PWM_GAUGE from the dropdown box at the top right.
• Save and exit the Configurator.
• Open MegaTune and connect to the ECU, and from the SETTINGS menu choose IDLE CONTROL.
• Select the PWM Warmup ‘Algorithm' and then you can configure the values for your vehicle and click ‘Burn to ECU'.
  

MS2/Extra closed loop settings can be found in the base map below.

Coolant (CLT) / Intake (IAT/MAT) Temperature Sensor Calibration

You can use your stock IAT and CLT sensors, and with the MegaSquirt-II you can calibrate these sensors through MegaTune.  It's best to leave the standard R4 and R7 'Bias Resistors' in place in the MegaSquirt and just configure this in the software.  You get better accuracy this way.

• Open MegaTune>Tools>Calibrate Thermistor Tables
• Select 'Coolant Temp Sensor', Select 'Fahrenheit', and enter these values:

• Click OK and the Coolant sensor will be calibrated.
• You're not quite finished yet though--- You need to repeat these steps, but choose 'Air Temperature' as the sensor table and use the same temp and resistance values from above as the sensors use the same curve.  This will calibrate the IAT as well.

NOTE-- Make sure you chose Fahrenheit or your readings will be WAY off with the above values....

More Information

• Everyone should thoroughly read the MegaManual.  I mean... you wouldn't buy a new doo-dad and install it without using the manual would you?  OK now seriously though... this is your pride and joy we're talking about here...  read the manual and the FAQ!!!
  • Read both the MS1 and MS2 sections, not all of the MS1 section will apply to you, but MUCH of it will, and the MS2 section isn't really complete without this information.
• Another great resource I refer to often is the MegaTune Tuning Software Manual