Megasquirt FAQ, writeup (Updated 30/10/09)

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pit_celica

Member
I emailed you the wiring diagram files.

The tach input came from both negative side of the coilpack. Run this line to your stock tach input in the IG1 or IG2 connector... I don't remember which one...

My diagram explain it well.

If anyone want them, let me know how to put it on a server like photobucket but for any type of files, and I will be glad to share it.

Sam
 
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tw2

New member
Thanks, I can load them onto the alltrac server if you like? I will update yours which is already on there.

So basically if you only remove the stock ecu and use connectors C, D and E to make your megasquirt connection then the only additional wiring is:

- EDIS with VR sensor, noise filter and coil pack
- Tacho signal board to pin 14 IG1
- Wideband wiring
- Wiring for GM IAT sensor
- RSC 40ohm 50w resistor to enable idle up valve to work

If you keep the stock loom and keep IG1 and 2 plugged in then no other changes should be needed. Is this correct?

I am trying to make sure I haven't missed anything since all of this is new to me and apart from the actual MS wiring itself nothing else is really obvious.

Do we have two coolant temperature sensors? One for the gauge and one for the ecu?
 
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tw2

New member
Here is my 1st attempt at a stock 3sgte loom to megasquirt adaptor harness. It isn't pretty but I think it might work ok.
Plug3.jpg

All of the wires in the wiring diagram I made I have confirmed are those particular colours and locations in my JDM gt4 with the exception of EGR etc which is not present.

I will probably check resistance, wire colours and locations all again for all the connections prior to installing MS.
 
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Quark

New member
Hi TW2, Looks good, and its a great idéa, I just think you make it a little to long to fit stock ECU location.

About settings, I will rather have you ask, if there is something thats bugging you, then writing alot down.

This is my 3´th MS build, so I have been around, but not on 3sgte.
 
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tw2

New member
Haha yeah I didn't want to shorten it too much in case I messed it up. I will have to coil it in a circle on top of the ecu or something. Thanks I will ask you some questions when I am closer to setting it up.

I might still remove the whole engine loom and wire it straight to the MS loom once the car is running and tuned. Then I can remove all the excess unused wires at the same time.
 
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pit_celica

Member
the link doesn't work...

BTW, what kind of fuel are you using (octane)? What is your boost set at? How are you listening for knock? Using knock sensor? Using det cans? Let me know!

Sam
 
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tw2

New member
pit_celica":57eclff5 said:
BTW, what kind of fuel are you using (octane)? What is your boost set at? How are you listening for knock? Using knock sensor? Using det cans?
Click to expand...
x2. It would be really great to have a complete map like this to just load on, listen for knock and leave. I plan on using a retarded version of the AEM map to tune fuel first and then try one of the maps you guys have posted.
 
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Quark

New member
http://www.msextra.com/download/file.php?id=9682

Regarding knock/ping. Use your ears and feelings. You can feel when the car is knocking, its not pulling so hard as before. Knock has a very high deep sound, you will for sure cut rpm if you hear it. Ping has a lighter sound and is not so destructive. I have only had the 3sgte to ping (even with the original ecu), but i got i removed by cutting 4 degress of the spark table from AEM.

There is really no safe way to detect knock at high RPM, all knock sensors react to slow, and all sensors have there own setup. So using a knock detection with the MS is useless, and by best does more harm than good, because you think you are safe, because of you knocksense system.
 
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Quark

New member
I use only 95 gas. Tw2 build your own map with a Wideband and Megalogviewer, its very easy.. Our maps are no good for you, expect ignition.
 
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tw2

New member
Thats what I mean, I will obviously make my own fuel map since I will probably have a completely different fuel system and VE mods just by chance.

So did you simply listen for knock? Or did you use detonation headphones?
 
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tw2

New member
I read an article which said that listening is the worse way to detect knock. It is very hard to pick it up unless it is quite bad. Electronic knock detectors are better but it still needs to be significant before they will pick it up. The most sensitive way is to listen with either a stethoscope on a dyno or make headphones which are the best way. If you use an electronic amplifier for them it is very good and you can hear the slightest ping.

This is what I have read and I would be careful with your map if I were you.
 
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Quark

New member
If you cant hear the knock, then its not bad.. :) hehe People have alot of opions about this area. Read the tuning part of megamanuel.

Eletronic pickup is only good for low rpm, not high, simply because its to noisy for the eletronic to pick op the knock or ping. On top of that, if you use a eletronic pickup circuit for your ms, then it needs to be adjusted for the engine and for the sensor, not something you can do yourself.

You should do what you feel like, I´am not so worried because I have another engine that I will drop in anyway. But hand on my heart, that ignition map that I uploaded dosent ping or knock.
 
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tw2

New member
I meant an aftermarket unit, something like a J&S safeguard or whatever they call it. I am just saying what I read. I will be playing it safe since I don't really have an option for a blown enigne but I have no tuning experience. I will probably try your ignition map since it saves me creating one myself but I will make some headphones to test it.
 
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Quark

New member
Its okay. People have alot of opions about tuning! ALOT. If you are on at budget, and dont want to risk anything, then pay a tuner to do it for your.

The reason why I dont it like I do, is because I´am a DIY guy, and I have paid my lesson money many times, but I am getting smarter everyday.. :-D

The first supra I made, put down something lige 550 crank hp, and I popped a pistons because of my homemade waterinjection who got stuck open.. Shit happens :-D

The next supra made ~430 crank hp and lasted a long time.
 
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pit_celica

Member
So, any update on your projects guys?

For my part, I'm currently redoing my whole engine wiring harness. It should be finished this saturday. I'll post pics of the finished product.
 
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tw2

New member
I have my pulley spacers for my trigger wheel and picked up the first parts of my VR sensor mount from the engineers this morning. I have some alluminium to finish it off sometime. Then I just have a couple more projects on the car- intake manifold, re-do exhaust, intall profec spec 2 instead of crappy MBC before I order MS. I will probably get it in about 6 weeks time.
 
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