# How to: Megasquirt V3 board setup for MSnS-e ignition



## TheTimob (Sep 13, 2003)

Here's how one mods a V3 board for MSnS-e (Megasquirt I processor) to work with a VW distributor.
I think this is the ideal setup for reliability. The Megasquirt I processor is VERY inexpensive, hell you can buy like 8 or 9 of them for the price of the MS2 daughter card. BUT - I really like the V3 PCB because of the better circuitry, better board, more options built in like the ignition driver, and it has protection against faulty connections and all that.
330 OHM 1/4 watt resistor. Solder it to a jumper wire.








The heat shrink it - so it doesn't short out.








Run da wire across the board to the corner hole








On the other side, form the jumper wire into a hook, and solder it onto the leg of R26, toward the DB9








Now, add the small jumper from IGN to IGBTOUT








Make sure that TSEL is jumpered to OPTOUT
and that XG1 is jumpered to XG2








And lastly, make sure TACHSELECT is jumpered to OPTOIN








Now, for the wiring of the spark. The hall sender on a VW can use either +5v or +12v - it does not matter, it works fine with both. You need power and ground to the outer pins of the distributor as in the following pic:
I took +5v power and ground right from my TPS connector - they are right there. Make sure to run the wires well away from the spark plug wires. You can see in my pictures that I used Green for +5v power, Blue for the signal, and black for the ground. The Audi connector boot matches the split loom PERFECT!!
























Here's the whacky part. Megasquirt can't read the RPM from the hall sender till you add a 1K resistor between your signal wire and +12v. I added this right behind my megasquirt in the wiring harness. *THIS IS VERY IMPORTANT*
Then run the coil wire from Pin 36 to the negative side of the ignition coil. Power to the coil should come (with a fuse) off of the Fuel pump relay as in the diagram. If you run this new power wire, remove the one from the car from the positive terminal.
I used a shielded wire for my coil - I grounded the shield at the megasquirt side to one of megasquirt's ground pins. Your car's tach uses a Red/black wire, keep that connected to the negative side of the coil along with your megasquirt coil wire.
Here's the wiring diagram








I have two cars running on this setup. An 84 Scirocco with a stock 1.8 JH 8v, and a 92 Fox with an ABA bottom and stock top. Both cars are running stock Digifant fuel injectors, and digifant distributors.


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## need_a_VR6 (May 19, 1999)

*Re: How to: Megasquirt V3 board setup for MSnS-e ignition (timbo2132)*


_Quote, originally posted by *timbo2132* »_Here's the whacky part. Megasquirt can't read the RPM from the hall sender till you add a 1K resistor between your signal wire and +12v. I added this right behind my megasquirt in the wiring harness. *THIS IS VERY IMPORTANT*


You need it on 5v too. I'd do it on the board, just jumper the 5v to tach select.


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## TheTimob (Sep 13, 2003)

*Re: How to: Megasquirt V3 board setup for MSnS-e ignition (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_
You need it on 5v too. I'd do it on the board, just jumper the 5v to tach select.

I'm gonna try that out today, and remove my previous one.


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## apavlov (Dec 4, 2005)

I'm trying to get my megasquirt to work. I have fuel and spark, but the spark does not consistently fire, and fires at the wrong time. I am confused about how far the distributor should be twisted, and what trigger angle I should use. I am also not sure what dwell settings the VW coil requires. What do you have set up? And does the hall send a low-to-high trigger, or a high-to low?(with your setup)


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## need_a_VR6 (May 19, 1999)

*Re: (apavlov)*

Trigger should be low to high (XG1 to XG2 cut) and you need a pullup for both 12v and 5v 1k to supply from the signal. 
The trigger angle on all watercooled VW's with a distro should be about 60deg. You should set the fixed angle to 6deg and the timing light should flash on the 6deg mark when the distro is in the right spot. You can also lock at 0 if you don't have that mark but the car might not run well, depends. 
For the dwell 6 cranking, 3 running and 1 min work for most applications. Set it to fixed if you're using a 'smart' ignition amp or MSD.
Make sure if you're using a VB921 on board you have the output to inverted and non inverted if you're using a VW ignition module.


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## apavlov (Dec 4, 2005)

I have a 1k pullup installed at the harness connector from the +12 in to the hall signal wire. Do I add another 1k from the +5Vref to the hall signal? My hall is running off of the +5.
It seems from timbo's post that he ise trying using a pullup from the +5 *instead* of the +12 resistor.
Sorry for jacking the thread...this may be considered clarification for other noobs like me reading this this thread.


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## need_a_VR6 (May 19, 1999)

*Re: (apavlov)*

You need the pullup from the signal wire to whatever voltage your hall runs on. 5v, pullup is on 5v; 12v the pullup is on 12v.


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## 1.8T16vhead (Aug 3, 2006)

*Re: (need_a_VR6)*

so what one is right 

































for the v3 board


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## apavlov (Dec 4, 2005)

As far as i can tell, the 2nd one is the only one that uses the VB921 to drive the coil directly, the first and third use the stock Bosch ignition module, and the 4th is a red X. Any of them are right, it just depends on what setup you want.


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## Reijer (May 15, 2007)

*Re: (need_a_VR6)*

hi there
i don't get it...







you said: 

_Quote, originally posted by *need_a_VR6* »_Trigger should be low to high (XG1 to XG2 cut)

but whem i'm reading the manual on msextra, the setup from timbo above is for hi to low.....
the setup for a hall sensor for low to high is way different... (xg1 to tachselect and tsel to optout)
wich one is right and should i use for a g60 engine??
Reijer


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## need_a_VR6 (May 19, 1999)

*Re: (Reijer)*

I always use the low to high circuit and trigger angle of ~60 and it works great.
You can use high to low, but the trigger angle can become low (under 40deg) which can limit your max advance.


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## sdezego (Apr 23, 2004)

*Re: (need_a_VR6)*


_Quote, originally posted by *need_a_VR6* »_
You can use high to low, but the trigger angle can become low (under 40deg) which can limit your max advance.

If you go this route (like I did) you should up with a Trigger Angle of ~0* which is just as acceptable as TA of 60* (leading edge vs falling edge). It's only when you end up with a TA of 10-40* that you can be screwed up and not be able to attain full advance.
I think it is just a matter of preference, but correct me if I am wrong.
Also, for the 1k Pullup, I used weatherproof ATC fuse holder near the Distributer plug (+V to sig) and then took and ATC fuse, snipped the bridge and soldered the 1K across the back. Plugged it into, closed the fuse holder's rubber cap and viola. It is a Immobil device







shhhh 
S


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## need_a_VR6 (May 19, 1999)

*Re: (sdezego)*

With a trigger of 0 you're in next cyl mode, which can get confusing. The stock one is low to high and that's why I use it.


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## sdezego (Apr 23, 2004)

*Re: (need_a_VR6)*

Makes sense. Thanks for that tidbit.
I think the reason I ended up this way and any others with the same config, is by ignoring anything on the tex during the build and just following the std B&G directions for Dist on -e. Then afterward, realizing the VW hall needs the 1K Pullup and adding it in, but never going back and making the board change.
I personally never went back to make any board changes (As simple as they are) because I will need to revist things when I go from Dist to 60-2 very soon anyway.
Shawn


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