Hey everyone,

I've just finished a major update to my Megasquirt install article. It now covers all current versions of the Megasquirt including MS1, MS2, MS3 and MS3-Pro.

When I say "step by step", I mean a complete writeup that covers the entire process from starting with a bone stock car, to wiring in the Megasquirt, programming it in TunerStudio and even some basic tuning instruction. The writeup includes how to choose your Megasquirt version, what you need to do to prepare the car, parts required, mods to the Megasquirt (if applicable), wiring it in with full step by step instructions and schematics, programming the Megasquirt, first startup and a little basic tuning. It's broken down based on Megasquirt version with wiring and programming sections for MS1, MS2 and MS3/MS3-Pro. A base map is available for MS3 / MS3-Pro which will give you a good place to start your own tune.

Much of my previous information has been updated as well. Megatune has been replaced with TunerStudio, and MS2 settings now reflect the most current firmware. I have also made some corrections, updated some links and in general, fleshed out a lot of the information.

In my opinion (though I am biased) it may be the single greatest Megasquirt writeup outside of the Megamanual and MSExtra sites.

You'll find it here:
How To Megasquirt Your 2nd Gen RX-7

As always, I look forward to any feedback you may have.

 

The write up is much appreciated Aaron. How did you come up with the required fuel values for the 460cc and 550cc injectors? When plugging 550 into the calculator I get a required fuel of 15.9 which vastly differs from the values you're stating to use.

 

The newer firmware revs should be set up as "rotary" stroke, and the mazda-specified displacement of 1308cc should be used rather than 2616 or similar.

This should yield a req fuel of 8-10 or so.

 

Awesome Aaron. I've been waiting for this, THANK YOU!

 

I ran the VE calculator but as mentioned already, there was a firmware change between now and when I was making those screenshots. With the new firmware the displacement should be entered as 1300CC and with the stroke set to rotary it will give the correct numbers. Older firmware wanted to see 2600CC.

You don't need to use the VE calculator though. Just type in the numbers I provided.

I don't think the engine CC number is used for anything but the VE calculator. Someone will correct me if I'm wrong but at least in the older MegaSquirts it was only used to calculate Req_Fuel.

 

The CC number is still used for req_fuel calc.

Ken

 

So to clarify, is it used only to calculate the Req_Fuel value using the calculator, or is it used in the live fuel calculation while the ECU is running? One means I have to change my screenshots, the other does not. Firmware changes so quickly that there was an update while I was working on the programming page.

 

On the Parts-list page (How To Megasquirt Your 2nd Gen RX-7: Parts List) you mention that the S5 NA injector plugs are hard to find - they are available at Ludwig Motorsports, "Denso Injector Connector":

http://www.lms-efi.com/sunshop/index...duct_list&c=25

 

Official word from MegaSquirt:

I replied that this is very dissapointing - given we're paying $90 for a pre made harness that we then have to hack into with a $15 part. I figure maybe if enough of us complain they'll bring it back

~Geoff

 

Adjusting pots
How To Megasquirt Your 2nd Gen RX-7: Modding And Setting Up Megasquirt MS3X

So you mention that we need to back the pots out all the way, and that there will be a "click" or an "indent." I've been going on these things for a long time (at least 10 minutes each, 15-20 on the first one) and have felt or heard nothing distinguishable.

I've heard a very subtle tick noise, which at first i thought was the sound of the pcb flexing under the light pressure of the mini screwdriver. I decided to call that the click you were talking about and back it off and tighten again, but if i try to get the click again its not there. Is that what you're talking about? It was so quiet literally the sound of breathing could cover it up.

 

That's it. It's very faint and can sound different between two different pots. The screws on the pots have a spring and shoulder so they don't fall out of the threads. You can keep spinning CCW forever but after the first click you're not really doing anything.

 

Yep. 5.0 Motorsports has them as well, I've even ordered them. Just sort of forgot to include that as I was concentrating on all the new content. Added to the list of minor updates to be made next time I'm in the mood.

Yeah, that's a little annoying. I don't know why the main harness would have been updated with the double shielded cable yet not the MS3X harness. Fact is most people who are using 2nd trigger are using VR sensors. At least DIY now carries the dual shielded cable so I can update the parts list with a source.

The noise on the DIY supplied pots is very, very faint and easy to miss. The good thing is that the pots are clutched. You can turn them forever and it won't hurt them.

 

I've been around airplanes for the last 35 years I've given up on trying to hear the damn things. LOL

 

On the Leading Coil wiring, you mention hooking up the MS3 trigger to the red wire and "that's it"... There are two wires on the igniter, the red one and a tan one (i think, maybe its black), I'm assuming the other wire is 12v switched power? Seems pretty obvious but you specifically say only hook up one wire to the Leading Coil. Just wanted to double check.

I'm putting the MegaSquirt on an FC engine, into an FB chassis/harness, so all of these connections must be either extended from factory wiring or pulled new. Don't want to make any assumptions that I shouldn't.

 

You don't mention which wire on the trailing coil is for tach signal, so i'm guessing between the grey wire and yellow wire. The factory wiring diagrams only show harness side colors, not igniter colors, so its harder to determine. Adding that info would be nice

UPDATE: some internet sleuthing found this old diagram (had to use the Wayback Machine as the site it was hosted on is NLA). It's the yellow wire.

 

Great find Geoff!!! Just so I'm clear the pink and the white are the trigger wires?

 

As the writeup deals with installing a Megasquirt on an FC specifically, the FC harness already provides 12V to the coils.

But since you are installing on an FB, you'll need to run a switched 12V wire from the main relay (which powers the ECU) to the trailing and leading coils. That wire connects to the TAN wires at each coil. Note the leading coil has two tan wires. The coils are about a 10A draw so if your main relay is already loaded (shouldn't be) then you might want to use a separate relay for ignition with its own fuse.

Yellow wire. Will hook directly to the SA/FB tach.

Oddly I am pretty sure I mention this in my Cosmo Megasquirt video. That video will help greatly if you are Megasquirting an SA/FB as the Cosmo as well needed all the wiring for ignition.

 

Just finished installing my MS3X while relying heavily on this write-up, and it was a success! I didn't realize just how conservative (rich) the provided VE map was until I tip-toed my way into boost for the first time and was met with a boggy 9:1 AFR. An hour or so with VE analyze cleaned that up though.

Thanks!

 

That's on purpose so people don't post things like "I used Aaron Cake's map and it blew up my car!". I considered just setting boost cut to 1 PSI but then that would create a flurry of posts with people wondering why their car stops running when they try to go into boost. Always best with any map to start way rich and lean out from there.

 

Might want to add a note that the new Firmware and TunerStudio register the engine as 1308cc, not 2600cc.

How To Megasquirt Your 2nd Gen RX-7: Programming The ECU (MS3X / MS3-Pro)

 

Yep. Unfortunately the firmware was updated while I was making the writeup. Such is the nature of working with an ever changing and improving product.

But, if the user just types in the numbers I have provided (assuming stock sized primaries) they are good to go without using the VE calculator.

 

You mentioned in your write up that you need a few cards to build a MS3X. So I am guessing that this kit, linked below, is still missing pieces? I am currently still try to make up my mind on what version to run. I am not sure if you could help me out.

MegaSquirt-III Engine Management System w/PCB3 - UnAssembled Kit with black case DIYAutoTune.com

 

That kit is the basic MS3 kit (I will have to update the writeup with a link) which gives you the main board and the MS3 daughter card (CPU). You'll need to add the MS3X expander card to get sequential injection, the extra I/O, VR conditioner, etc.

MS3X:
MegaSquirt-III MS3X Expansion Card DIYAutoTune.com

 

Anyone had any success with the Bluetooth and GPS add-ons?
I'm thinking of throwing those in there

 

I'm using MSdroid and my phone or tablet GPS. It's a pretty low ping rate so I don't think it'd be useful for 0-60 or quarter mile, but it's free. It's loggable via USB OTG or Bluetooth. It's still in beta and bugs are being fixed every week, but it's nice to have speed displayed on my tablet screen and logs.