Megasquirt Support Forum (MSEXTRA)

See it in action here! https://www.youtube.com/watch?v=zU27vj9RZaw

Just thought I'd make a quick post for getting my 95 Saturn SC2 (LLO) fired up on MS2-Extra 3.4.2, 3.57 board, using the stock OBD1 ICM.

GM DIS Pinout
6pin connector:
A) 12v power (pink), needs to be hot in run & crank. Use 7.5 amp fuse.
B) 6X ref (white) -- unused, might drive a tach output?
C) EST wire (WHITE) -- used for Timing Advance signal. Wired to D14/SparkA.
D) Reference High (Purple w/white tracer) -- Tach input to MS
E) factory dash tach on 92 dash
F) EST Bypass wire (Tan w/black tracer) -- when 5v is applied, module will use timing signal from MS on pin C. When no signal, timing should be in limp-home 10* BTDC. I have this wired to D16 via SPR3.

5pin connector:
A) Positive crank sensor wire (yellow) -- goes to crank position sensor
B) Negative crank sensor wire (purple) -- goes to crank position sensor
C) not used
D) Reference low (red w/black tracer -- Goes to MS sensor ground
E) High current ground. Ground to the block.

Used with Basic Trigger ignition setting, with a 10 degree trigger angle, it seems to work pretty good.

Nice, what's your plan with it?

It's going into a Chumpcar endurance racer since ECU is now a no-points modification.

-Dave

Just wanted to post an update. So I migrated the MS2 to our '92 Saturn SC2 Chumpcar this past winter. The Megasquirt made its racing debut at the 24 Hours of Nelson Ledges this weekend, where we took 3rd overall and 1st in class! The ECU never missed a beat during the race and allowed us to finally make it a full 2 hours on fuel, something we could never do with the stock ECU. We covered over 1800 miles in harsh (hot) conditions. It was definitely a factor in our performance.

thanks to James, Ken, Philip, DIYAutotune and all the folks who've made MS2/MS3 what it is!

edit:
2018, 24 Hours of Nelson Ledges, 3rd overall, B-class winner,
2019 Double-10s @ Indy: B-class winner on Sunday
2019 24 Hours of Nelson Ledges, 5th overall, B-class winner

https://forum.champcar.org/topic/18445-mostmint-racing/

-Dave

I really hate to necro an old thread, but I have a question about your wiring that I cannot seem to find anywhere else.
I understand the 6 pin connector slot D (ICM) is used for the tach input signal for MS. But on the MS end, what did you connect the negative side of the tach input to?
In other words, you have the positive tach input signal going to the positive MS tach input on the DB37 connector. But what did you supply for the negative side of the MS tach input?
Thank you,
Chris

P.S. I am currently running fuel only on my 95 with a MS2 v3.57, switching to fuel and spark after I finish my complete harness. I would like to used the OBD1 ICM output for the tach input to MS instead of the crank sensor VR signal, since the ICM provides a cleaner signal.

Sorry I didnt see your 2nd reply on Youtube... pin 1 on MS doesn't need to be hooked to anything. You're getting a hall-signal from the ICM. The tach reference signal from the ICM (6pin connector, D, purple/white tracer in OEM harness) goes to MS pin 24. If it's not listed above, you don't need it. We have thousands of racing miles on this setup.

Good luck,

-Dave

ChevelleFan wrote:Sorry I didnt see your 2nd reply on Youtube... pin 1 on MS doesn't need to be hooked to anything. You're getting a hall-signal from the ICM. The tach reference signal from the ICM (6pin connector, D, purple/white tracer in OEM harness) goes to MS pin 24. If it's not listed above, you don't need it. We have thousands of racing miles on this setup.

Good luck,

-Dave

Dave,
thank you very much for the clarification, hoping to be running by the end of the weekend!