MS3/X Assembly for GM DIS

[cammmy]

Hi Guys

New to MS and would appreciate some advice on my build. I've got a PCB 3.0 MS3/X and am putting it into a Lotus Esprit GT3. I'm going to be keeping the standard GM DIS setup and idle control valve.

The Idle control valve is GM 17111826 (stepper motor)
I believe the DIS module is GM 10467214

Now, I've just been stepping through the assembly instructions and as told, I put aside the following parts:

"17) Find Q16, (Ignition Transistor), D14, D15 and D16 (LEDs) Q4 and Q20 (small transistors) and MS3 CPU
card. Put these to one side but don’t lose them!!"

I stopped for the night, came back after work today and carried on. Unfortunately I realised that I've now soldered in Q4 and Q20. Is this going to be a problem? I've done a bit of a search and I don't think so but am not certain.

I've not soldered in Q16 yet. Will the DIS need this or can I leave it out?

I'm new to all this and having a bit of difficulty getting my head around it all. I'm trying to achieve as drop in a replacement as possible. On this car that also means boost control and sequential injection (4 primary and 2 secondary).

In the future I'd like to configure launch control and flat shifting

Any help appreciated.

Cheers
Cam

[cammmy]

Hi All

I've done some more reading and think I'm okay with having Q4 and Q20 installed.

For the majority of installs not using PWM idle on the mainboard, solder components Q4, Q20, R39 and D8 in
place. Note, this gives you a programmable output that can drive a relay e.g. cooling fan on FIdle (Pin 30 of the
db37).

Still not 100% about Q16 but will continue reading and hopefully I'll spot the answer.

Ta
Cam

[cammmy]

Further study suggests:

No Q16

Follow below:

a) Solder a link between VRIN and TACHSELECT
b) Solder a wire between VrOUT and TSEL
c) With a small screwdriver, turn the pots, R52 and R56, about 12 turns anticlockwise (sometimes you may feel
d) Turn R56 back about 6 turns clockwise.
Optionally, when adjusting R56, you can measure the voltage at the "top" of R54. You'll need the board powered
up. Set your meter to volts, and connect the +ve probe to the top of R54 and the -ve probe to ground. Adjust
R56 to get around 2.5V on your meter.

E = Electronic spark timing (EST) from Megasquirt IGN - Pin 14 on MS3/X
R = Reference (REF) to Megasquirt Tach in - Pin 24 on MS3
B = Bypass from Megasquirt bypass output (SPR3 shown) - Pin 33 on MS3/X
G = Ground to Megasquirt Sensor ground

Following settings:

Ignition capture = "Falling" (check!)
Spark output = "Going High" (check!)
Spark A output pin = "MS3X spark"
Dwell type = "Standard Dwell"
Nominal Dwell = "3.0"
GM/HEI options = "GM bypass"

Is anyone able to confirm? Sorry for the spam, just a bit nervous about getting it right.

Ta
Cam

[DaveEFI]

Hi All

I've done some more reading and think I'm okay with having Q4 and Q20 installed.

For the majority of installs not using PWM idle on the mainboard, solder components Q4, Q20, R39 and D8 in
place. Note, this gives you a programmable output that can drive a relay e.g. cooling fan on FIdle (Pin 30 of the
db37).

Still not 100% about Q16 but will continue reading and hopefully I'll spot the answer.

Ta
Cam

If you're driving a stepper motor, this uses a different and separate driver from the Fidle driver. Leaving the Fidle driver free for other uses - if you've built it.

Q16 is a high current ignition coil driver - very rarely used on its own. Mainly with points ignition.

[cammmy]

Brilliant, thanks. I'll finish building that then and will leave Q16 off.