I was to start off by saying nothing in this post is my own work… It is compiled from information in various threads on this forum (mainly the FAQ thread). I’m posting this because I don’t know much about Megasquirts and I want to make sure I understand what needs to be done before attempting the mod.

This procedure for a Megasquirt2 (purchased with built-in VR signal conditioner) going in a S4 FC. Please let me know if it looks correct and complete. Thanks in advance.

Step 1 – Connect CAS to MS2
A. Build a second VR signal conditioner for trailing ignition system in proto area of MS2 V3 board (shown below).

B. Make the following connections
Ne+ (CAS) to pin 24 of DB37 on MS2
Ne- (CAS) to pin 7 of DB37 on MS2
G+ (CAS) to VR2 in LM1812 circuit
G- (CAS) to ground on LM1812 circuit
OUT2 to “JP4" on the MS2

Questions:
1. Does the 82k resistor need to be replaced with a 39k resistor like the 56k resistor needed to be replaced by a 39k resistor (in the omitted left side portion of the complete dual LM1815 signal conditioner)?
2. Does OUT2 need to go through a 1k resistor before going to “JP4” like it did when it used to go to pin 11?
3. Is the 0.01 capacitor a 0.01 F or uF?
4. Is the 33 capacitor a 33 F or uF
5. Where is JP4 located? I looked at the V3 schematics but could not find it.

Step 2 - Install a 4.7K resistor from negative lead on each LED to +5V source (picture shown below).

Step 3 – Connect LEDs to Igniter
Connect the following…
Negative lead of LED17 to leading igniter (IGt-L)
Negative lead of LED18 to coil select wire on trailing igniter (IGs-T)
Negative lead of LED19 to IGt wire on the trailing igniter (IGt-T).

Question
1. Are there any additional connections that need to be made to make the trailing ignition work?

Step 4 - Since I’m planning on using the stock air temperature sensor – replace R4 on MS2 board with a resistor between 30k and 50k.

Step 5 – Connect MS2 to wiring harness using following connections…
DB37 Pin 7 to Ne- (CAS)
DB37 Pin 8, 9, 10, 11, 19 to ground
DB37 Pin 20 to Intake Air Temp (positive side)
DB37 Pin 21 to Coolant Temp (positive side)
DB37 Pin 22 to TPS (signal)
DB37 Pin 23 to Narrow Band O2 (positive side)
DB37 Pin 24 to Ne+ (CAS)
DB37 Pin 26 to TPS (5V reference)
DB37 Pin 28 to +12V source
DB37 Pin 32 to Front Primary Injector (negative side)
DB37 Pin 33 to Rear Primary Injector (negative side)
DB37 Pin 34 to Front Secondary Injector (negative side)
DB37 Pin 35 to Rear Secondary Injector (negative side)
DB37 Pin 36 to Ignition Module????

Question
1. How should the leading ignition be connected?

Step 6 – Upload Settings
I’ve seen various settings posted in this forum… Are there any sets of complete settings available? Is this something someone can share with me in the form of a file to be uploaded to the MS2?

Step 7 – Start ‘er up and break out the wideband for tuning.

 

No. Use the 82k resistor.

Yes.

That is uF

It's 330 pF

It's on the MS2 itself.

No.

All good, except I recommend getting a wideband instead of using the narrowband.

Pin 36 doesn't need to be hooked anywhere.

The way you described above to LED17

You're mostly on your own here... I didn't drive around on ms2/extra ... just idled, did some throttle blips... pissed off the neighbors... we're going to be tuning (possibly on the dyno) at the MS meet this weekend.

If you want to post an msq after doing what you think your settings should be, post it, and I'll look over it, and let you know what's wrong.

Ken

 

Thank you very much! I feel pretty good about doing this now that it's clear in my head... I actually already have a wideband for my PLX-R500. Also, I ordered the parts for the signal conditioner from Digikey today. With any luck I'll be able to get started this weekend!

I do have two more questions... What software/firmware should I use? Also, do you happen to know of any sources for stock tables (fuel, ignition, ect)? I poked around for both these but didn't find them after searching for a bit... I'm going to keep looking but maybe you could point me in the right direction. Thanks again!!

 

Lastly, I remember reading somewhere that you should replace the TPS with one that reads 0-100% over the entire range of motion of the throttle body (not WOT at <100 throttle)... What TPS do you recommend? Thanks again!

 

You don't really need a TPS now... if you use EAE (enhanced accel enrichment) it runs off the MAP sensor... so the only thing the TPS is good for is enabling fuel cut. The stock TPS is fine for that..

For software, you'll want megatune 2.25 I believe ... it's the latest stable version.

For firmware, you'll want ms2/extra 1.0.1, which I'm releasing over the next day or two. I fixed a bug which was keeping the second trigger from working properly, and fixed a staged injection bug that made the gradual transition incorrect if you're using different-sized injectors... both of those bugs exist in ms2/extra 1.0.0.

Ken

 

The components from Digikey arrived today. I think I have everything straight now. Thank you very much for all your help. I'll keep an eye open for the firmware you mentioned you would release. Thanks again!

 

Hi Ken,

I'm building a new harness now. Hopefully everything will come together. I was just wondering if you released the MS2/extra 1.0.1? Thanks!

 

yes I did.

Ken

 

Hi Ken,

I looked for it in the firmware sticky thread but didn't see it. Did you release it elsewhere? Thanks for your help!

 

It can be found on msextra.com in the ms2/extra section.

 

Sweet, thank you very much!