# Megasquirt MS3 1.8 20v Naturally Aspirated



## mk1scott (Jun 24, 2002)

*Megasquirt MS2 1.8 20v Naturally Aspirated*

Hey guys, I'm new to standalone management but have been reading for quite some time, picking up parts and am ready to play with Megasquirt (MS2) using the Microsquirt Controller. I have a complete 20v 1.8t AWP motor with full harness and sensors that I'm going to run naturally aspirated (have never been a turbo guy) in my MK1. I'll be switching over the drive by wire to drive by cable through an ABA throttle body with TPS. My intent is to start learning Megasquirt and build from there but have some questions/ need some guidance. In a years time, I want to build upon this and go high compression, big cams and individual throttle bodies. But the current plan is to just wire it up and get it running. As I clean, prep and check the engine in the shop during the day, I want to prepare the wiring at home during the night. I have all of the OEM sensors and wiring harness to splice into.

I currently plan to wire up with;
- Knock sensor(s)
- Intake air temp sensor
- Coolant temp sensor
- Stock injectors
- GM MAP Sensor
- ABA 2.0 throttle body with TPS
- Wideband O2 sensor

And that list comes with a few questions;

Keep the coil on plug ignition with the stock cam position sensor? Most of my search says this can be a real pain in the ass but those threads are from years ago
Recommendations on a Wideband? I have zero intention to run an AFR gauge in the car - so if the plus side to an O2 sensor is the fancy gauge, not a concern
I have both knock sensors, but is both necessary? Should I just run one? Which one?

Those are probably all the questions for now. Still going through the wiring and removing the factory tape and loom. Damn tedious work. Oh, and, would anyone have a base tune for the AWP 20v with or without turbo as a starting point? Or would I be better off with a 16v tune?

Thanks in advance. I plan to spend a lot more time in this forum :beer:


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## ps2375 (Aug 13, 2003)

You don't need the GM map sensor, as the MS board has one on it. 

For the wideband, I use an older system from http://www.14point7.com/, but the Spartan would fit your application perfectly.
I'm not sure how the MS3 deals with knock sensor(s), but I'll be fitting Knocksense (http://www.viatrack.ca/) to my next motor with 10:1CR, and I run an MS1. And for a 4 cylinder, 1 sensor should be just fine.


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## Prof315 (Jan 5, 2009)

MS3 works fine with the stock cam sensor just use Polling level as the capture choice. However the MS3X coil drivers won't work with the stock VAG coils without booster circuitry, there are a bunch of threads about that issue in the MS/Extra forums. Personally I like using GM LS coils on my 1.8L 20V installs.

There is an add-on 2 channel knock module available for the MS3 that will fit your needs perfectly. And for a wideband, I agree with PS2375......14point7 Spartan is the way to go.


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## mk1scott (Jun 24, 2002)

Thanks guys :beer: It helps steer my build in the right direction.

I'd like to pose the debate between coil-on-plug versus plug wires and coilpack (wasted spark)? I like the idea of keeping it as OEM to Volkswagen as possible rather than running something like a Ford EDIS system or (cough) GM parts (cough/ ignore the GM sensor I plan to use). I'd like to set myself up so that in the future when I move towards high compression, large cams and throttle bodies I won't have to revisit and start replacing the engines wiring and electrical.


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## ps2375 (Aug 13, 2003)

Seems you may have a bit of reading to do on MS, and I would get the build configuration buttoned down first, then see id MS will support what you want to do. It'll do almost anything with any hardware, some just takes more mods to make work than other stuff does.


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## Prof315 (Jan 5, 2009)

As PS2375 stated you can make almost any ignition work with MS. I personally like using GM LS2 truck coils for the following reasons:

1: They are effectively plug and play with an MS3/3X

2: They are just about the hottest ignition coil made

3: They are extremely reliable

4: The are easy to find for cheap at most junkyards


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## mk1scott (Jun 24, 2002)

ps2375 said:


> Seems you may have a bit of reading to do on MS


Haha, couldn't agree more. My original plan was to MS my 8v and go from there. I had everything buttoned up until this new motor fell into my lap last week. Now I'm in a mad scramble to get everything pieced together and am clearly jumping the gun on this. I've seen a handful of motors in a similar configuration as to what I want to achieve; however, the ignition system from motor to motor seems to have the most variances. The COP is my ideal goal but it seems much simpler to run a coilpack with plug wires.



Prof315 said:


> I personally like using GM LS2 truck coils for the following reasons...


Thank you for your recommendation and reasoning. I skipped passed both the LS1 and LS2 only because I wanted to keep it VW. But as I'm learning, I'll have to venture out of the VW parts bin to get this built.

Do you find it best to tie into the factory harness or start from scratch?


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## Prof315 (Jan 5, 2009)

For me (I build, repair, install and tune Megasquirt products for a living) it depends both on the condition of the factory harness and the customer's desires. In general though and certainly on my own stuff I start from scratch using the unterminated wiring harnesses that DIYAutotune sells, the 8ft version is done for most installs.


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## need_a_VR6 (May 19, 1999)

You CAN run the VAG coils from a modded MS1/2/3 you just need to run a PNP driver and not everyone likes to use them (or stocks the parts). 

MS3-PRO will run the VAG coils as-is. 

I agree that the LS1/2/Truck coils are an all around better choice in any case.

Unless you need/want to do a PnP setup, wire it all fresh it saves so many headaches later!


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## Gary_808 (Jan 2, 2014)

need_a_VR6 said:


> You CAN run the VAG coils from a modded MS1/2/3 you just need to run a PNP driver and not everyone likes to use them (or stocks the parts).
> 
> MS3-PRO will run the VAG coils as-is.
> 
> ...



Out of curiosity, why can't the ms3x run them out the Box? 

I assumed they were standard 5v logic Coils?


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## mk1scott (Jun 24, 2002)

I should have mentioned already, but haven't, I'm running the Microsquirt Controller.










I edited the initial post to include this information.


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## need_a_VR6 (May 19, 1999)

Ah big difference. The npn driver can't pull up high enough with the later coils 200ohm shunt resistor and wont fire. The pnp gets around that by direct sourcing the 5v. You can only drive 8 on an ms before you overload the 5v supply regulator. They are current hogs. 

If you have a uS and want vag you can run the hitachi bolt down coils (or highly unrecommended early push down coils). Those both work fine with direct processor and npn drivers.


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## mk1scott (Jun 24, 2002)

need_a_VR6 said:


> Ah big difference.


Yea, my mistake. I've been collecting parts over the past year and had started to forget exactly what I had. My car projects have been pushed to the side lately so it wasn't fresh in my mind. But now that I've unloaded my jetski and jeep builds I'm back focused on my VW's.


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## need_a_VR6 (May 19, 1999)

No worries, I don't do much with uS so I assumed you were using a std MS.


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## A2TDI (Apr 8, 2004)

I have run the edis system for years on my car and provides more then enough spark for over 500whp 20v.. I don't run knock sensors and I run an AEM wideband and tune off of that. I use a gm coolant sensor, gm IAT , GM tps on a chev astro 72mm throttle body, and a 4 bar map daddy map sensor obviously that map sensor you wont need lol. if you use the coil pack route do yourself a favour and make your own spark plug wires and hide the coil pack. I use 2006 chevy AVEO 1.6L spark plug boots and they sit flush with the vw valve cover.


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## A2TDI (Apr 8, 2004)

I hope that shows a good enough pic of my ignition wires.. Long wires but it never breaks up and thats with and old ford escort ignition coil.


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