The beginnings of a Megasquirt how-to guide

[icingdeath88]

Some preliminary discussion happened here in this thread (which is informative in general as well): http://www.subaru-svx.net/forum/show...451#post713451

This thread goes over my project/goals, etc and has a little discussion of the megasquirt: http://www.subaru-svx.net/forum/show...t=58090&page=4

Where my project stands right now, I need to make the engine that's currently in the car run on the megasquirt, without necessitating any down-time of the car, since I need it for work/school etc, since my brother is using my other car (the black 97) for the next couple months while he's saving up to buy a truck. Then, after I get that car back, and have moved to the new house, which has a garage, the engine swap and real fun stuff will begin, and the blue/6-speed car will be taken out of daily-driver duty.

I ordered a Megasquirt 3 Extra, a Break-out board, a GM IAT sensor, and some other little odds and ends from DIYautotune.com. Ordered 6 LS2 truck coils from ebay, and got some new connectors for the cam and crank sensors from here, since they were especially old and brittle. If you try hard enough, you should be able to find new OEM connectors online for most of what I connected directly to the megasquirt.

Anyway, here's a run-down of what I've figured out/done so far. I got a spare engine and body harness, and went through and followed the wires back from the sensors/etc to the ECU so I could be sure how everything's connected. Then, some of the wiring to the sensors at the engine, I separated, to connect directly to the Megasquirt, while some things I connected to the break-out board, which plugs in where the stock ECU does. Here's the ECU pinout, and the megasquirt pinouts underneath them:









(from here: http://msextra.com/doc/ms3/hardware.html#wiring)

Here are the wires that I connected to the break-out board (here):


ECU pinout location...........MS3/MS3X # (color)......................break-out board #.......................function

B62 - 23.........................MS37 (purple)................................4T..............................fuel pump relay

B59 - 2...........................relay...........................................1C..............................+12V to power everything

B61 - 16.........................MSX26 (green/orange stripe)............3P..............................Tacho

B59 - 21.........................MS7 (black/grey)............................1T..............................ground for CTS

B59 - 17.........................MS7 (black/grey)............................1L..............................ground for O2 (split from CTS ground)

B59 - 3 .........................MS21 (yellow) ................................1E............................. CTS signal

B59 - 6 .........................MS23 (pink) ....................................1K............................. O2 signal 1

B59 - 5.........................MSX22 (blue/darkblu)..........................1I..............................O2 signal 2

Ok, those are the wires I connected to the break-out board. The rest I wired directly to the megasquirt, to the intake manifold ground (at the back, pass. side of the intake manifold, just above the FPR basically), or to fused +12V supply. The +12V supply I used 2 of the small 4-fuse fuse blocks that's sold at DIYautotune, and each fuse box was connected to a relay, that's activated by the +12V ecu supply in the table above. This provides power to the Megasquirt, the IACV, the injectors, and the coils. The injectors and the coils are each split by bank among 2 fuses (5 amp each for the injectors, 10 amp each for the coils).

For timing the ignition, I am using the 12 tooth crank wheel, which is crank sensor #1 (the one tilted, to the (US) passenger side), and the cam wheel. The cam wheel is read as a single tooth wheel, and the crank angle sensor is 12 teeth, with no teeth missing = should be perfect for sequential COPs on the megasquirt. This is an important factor in whether or not I'd be able to switch back and forth to the stock ECU, because if I had to grind a tooth off the 12-tooth wheel, to do wasted spark, I wouldn't be able to change ECUs without changing out the crank sprocket, which would be hugely impractical.

The pinout for each plug is given below:
*Looking at the connector (not the sensor/device), with the clip side up, and the wires going away from you. Pins are from left to right.*

Device......Position from left to right.....MS wire (color)...Function
TPS..........1....................................MS26 (grey).......+5V reference from MS
TPS..........2....................................MS22 ................signal
TPS..........3....................................ground ...............ground

IACV.........1....................................MS30 (FIDLE)......IAC close
IACV.........2....................................+12V.................+12V to drive IACV
IACV.........3....................................MSX9 (Idle)........IAC open

Crank sensor*.1...............................MS24 (white)......Crank signal
Crank sensor..2...............................MS1 (black)........ground

Cam sensor....1................................MSX32 (dk green)......Cam signal
Cam sensor....2................................Any black ground on the MS main harness...Cam ground

Injectors....1...................................MSX INJ A-F (white/color).....Injector signal (grounded at MS)
Injectors....2...................................+12V at fuse box...................Injector power

IRIS**......1...................................MSX27 (VVT).........Signal (grounded at MS)
IRIS.........2...................................+12V at fuse box (shared with IACV).....power for IRIS solenoid

*The crank sensor should be connected using twisted/shielded wire, to prevent electrical noise. These are given in the DIYAutotune harnesses as such.

**The IRIS I actually haven't hooked up yet, I will need to test and make sure whether this will work in software or not. The VVT pin is a medium-current PWM ground signal, but there is a setting somewhere to change it to on/off instead of PWM, just need to play around with it.

The 2-wire CTS and IAT sensors, can be connected either way going to signal/ground, what's measured is the resistance.

All of the MS ground wires were connected to the intake manifold ground, except one (random) that was split off to provide the Cam sensor ground.

I am going to be using LS2 truck COPs, rather than the stock igniter module and coils. The wiring for the LS2 coils I found here and will follow that: http://msextra.com/doc/ms3/ignition.html#ignout

Spark plug wires I haven't quite figured out yet. I got some make-your-own plug wires at advance auto parts and I didn't notice, but the end that connects to the coil should be different from the end that connects to a distributor, which is what I got. So gotta return those and get some that will work.

If you are going to try using the stock igniter, you're on your own. Matt burned one or two igniters, and then added separate igniters, and in my testing I also burned out an igniter too. I don't know yet what needs to be done exactly, but figure it out.

The MAP sensor vac line is T-ed into the FPR line (easiest line to replace if it were to break.

I haven't removed any of the "definitely not going to be used" wires from the MS loom yet. I will wait until it's running before I start trying to clean up the wiring, which is a huge mess right now. There are wires taped up against things all over the engine bay. I gutted the glove box, and removed the AC evap core, to run my wires through the hole in the firewall that's then exposed. I don't really recommend doing the same, since it kind of FUBARs the whole ventilation system in the car (need to fix the airflow somehow to regain heater core function).

So far I have wired up all the sensors, and the break-out board, but neither the coils or the injectors yet (just no time). The sensors I could test without the car running I tested - the crank and cam sensors synced, I calibrated the TPS.

Tunerstudio has a calibration curve built-in for the GM IAT sensor. The CTS, uses a Bosch NTC calibration curve. I will attach a file with the calibration curve later, it's on the laptop at home. In fact, if you wanted, you could use a spare EG33 2-wire CTS as an IAT sensor, just input that calibration curve instead. Once calibrated, the IAT and CTS readings in tunerstudio were reasonable.

So far, I am using only a base map (.msq file) that someone uploaded to the MSextra forums a while back, that I think is also the one 2006eg33 started with. It can be found here: http://www.msextra.com/forums/viewto...?f=131&t=44607 I will upload the one I modified to match my wiring and the sensors/coils I am using later (slight, but important differences). Don't even attempt to use that one with my wiring. I'm hopeful that that map is close enough to work for me. If not I'll try doing what this guy was apparently able to do and convert one of the maps extracted from a stock ECU to the format that the MS uses, and just run it with that.

*More info to come after I have the injectors and coils wired up and finally try starting it up.*

[icingdeath88]

Reserved for updates

Update - added NTC calibration curve pdf for calibrating coolant temp sensor.
Added .zipped msq file for what the settings I have so far are.

[92 SVX]

very nice will be watching this space.

[icingdeath88]

Originally Posted by icingdeath88

If not I'll try doing what this guy was apparently able to do and convert one of the maps extracted from a stock ECU to the format that the MS uses, and just run it with that.

I think this guy got the hex maps from UK Phil's site: http://www.alcyone.org.uk/ssm/ecureverse.html

Maybe Phil or one of the others can help me make sense of that.

Also figured out that "O2 sensor 1" in the ECU pinout should be the right (passenger) side sensor, of bank 1, which is cylinders 1, 3, 5. And O2 sensor 2 is for bank 2.

The fire order is 1-6-3-2-5-4. The MS wiring will therefore be:

Inj/coil...cylinder#
A..........1
B..........6
C..........3
D..........2
E..........5
F..........4

I don't see a way to set up both the stock narrow-band O2 sensors and a wide band, but you can set up two wide-bands. I don't have a wide-band yet, I really need to order one but funds are short ATM, and I'd rather use a pair of wide-bands than a single one. For now I'll probably give it a shot with the narrow-bands.

[icingdeath88]

Well, here's some surprising good news. A buddy from the lab just happens to have an autometer wideband that he's not using. And I checked that it will work with the megasquirt, and it should. So if he'll sell it to me then I should have that going sooner rather than later.

And I just realized that this thread is sorely lacking in pictures, so I'll get on that right away. :P

[Stevebsy]

Are you tapping into the svx harness for the MS?

I swear I saw a place online somewhere that had the svx ecm connectors, I dont think it was a ms site but another aftermarket ecu. That would make things awfully nice....

Anyway...get those pics up!

[icingdeath88]

Technically, you can use the break-out board, which plugs into the body harness in place of the stock ECU, to do everything. So far, I haven't had to alter the body harness at all. However, to facilitate my own understanding and keeping track of all of the wiring, I am only using the break-out board for a few things, and keeping most of it on a separate harness, just for the megasquirt.

What 2006eg33 told me via email that he did was use a spare body harness to get the 4 body-side plugs that plug into the 4 engine harness connectors to do everything. That is a pretty clean way of keeping things plug-and-play, because you can leave the body harness of the car alone. He's got it in a legacy or impreza though.

Honestly, I am kind of shy to take pics of my car because the car itself is in kind of rough shape, and the engine bay is a mess right now because of all the wires all over the place. I have them literally taped up all over the place to keep them put while I'm driving. This would really be a lot easier if I could make the car undriveable for a while until it's finished.

[icingdeath88]

Good news, got it to start on the MS last night. Ran as ****tily as I can imagine, but I was pretty much expecting that. Had a ton of sync loss = not a clean enough reading from the crank/cam sensors. Most of the EJ and EG MS builds I've seen have required one or two resistors either inline or across the signal and ground wires in order to get a clean enough signal for the MS. So I need to figure out the best way to go about fixing that. Still, good progress, and I'm excited that it ran at all.

[TomsSVX]

Just making sure you noted the FSM's incorrect pin location for the ignition coils... Gave me a hell of a ride when setting up the Hydra. I logged the notes in the original hydra thread of which wires need to go where

Tom

[icingdeath88]

Originally Posted by TomsSVX

Just making sure you noted the FSM's incorrect pin location for the ignition coils... Gave me a hell of a ride when setting up the Hydra. I logged the notes in the original hydra thread of which wires need to go where

Oh, that explains the burned ignitor the first time I wired up the MS directly to the break-out-board. Right now, the coils are wired directly to the MS, so that's actually not an issue for me, but it will be a huge deal for anyone trying to get it working plug-and-play.

Found the post: http://www.subaru-svx.net/forum/show...7&postcount=64

Originally Posted by TomsSVX

I did take note of a couple typos in the Factory Service manuals though for anyone who may need them in the future. The pins for the coils are wrong which is what was giving me such a hard time. And since the igniter doesn't just pass the current, I couldn't trace them with a simple test of continuity. So I had to do it the hard way on at a time.

Coil-ECU connector-Pin
1-b62- 10
2-b62- 8
3-b62- 9
4-b62- 7
5-b62- 21
6-b62- 16

As always, thanks a ton for the very valuable input, Tom.

[icingdeath88]

I think I've sorted out the cam and crank sensors. Someone on the megasquirt forums suggested I use this board: http://www.msextra.com/forums/viewto...p?f=67&t=46150
instead of the megasquirt's VR conditioners. I don't quite know enough to explain what it does, but basically it acts like a noise filter and is also able to deal with a wider range of input voltage, and several people have had success with this board and the black subaru sensors, like on the EG33. So I got one and wired it up and gave it a shot and it seems to be working a lot more nicely now. Synced up right away on cranking and it didn't lose sync up to ~2500 rpms. I didn't try it any higher than that because I didn't want to rev it all the way without warming it up first. I discovered that cylinders 2 and 3 aren't firing, so that's the next thing I need to figure out. I also added a knock module, hopefully it will play nice with our stock knock sensors.

[icingdeath88]

Been looking over the wiring of the OBD2-1 adapter I bought from Tom, and I think I found another error in the FSM OBD1 ECU pinout. Pin B60 11 is assigned as both the MAF voltage and the VSS2 input to the ECU. And it can't be. After comparing it to the wiring diagrams I believe it's actually the VSS2 input. This isn't really relevant to my megasquirt project (at least right now), but I wanted to post it somewhere so someone can find it if they need to later.

[BackWoodsBob]

SUBSCRIBED!

Would have sub'd earlier but didn't know you had made a thread until you posted on rs25!

Thanks by the way , looks like I have some reading to catch up on!

[icingdeath88]

Yea, I have made some decent progress finally in the last couple of days, I'll post an update soon.

[2006eg33]

glad to see full documentation of this.

you could effectively end the enginemanagement woes with this engine.

you'd be a hero.