Project: MegaSquirt build

[timk]

Note: This is a copy and paste of my work log on the OCAU forum. I'll try to remember to update it, but it may lag a bit behind the OCAU one.

Hey all,

I've decided to build a MegaSquirt ECU which will eventually be fitted to a Mazda MX-5. This thread will detail the whole build process including testing, fitting to the car, configuring and tuning. Don't expect to see this thing completed tomorrow as it limited by my time and finances. I'll try to keep the information fairly general and include sources where possible (I will also add MX-5/BP specific info, but I'll make it fairly obvious when doing so).

Cheers,
Tim

[timk]

This thread isn’t here to tell you what MegaSquirt is. If you’re unfamiliar with MegaSquirt, you should visit the MegaSquirt site which explains everything fairly well.

If you’re starting out with soldering, I suggest that you tackle the MegaStim build before going for the MegaSquirt itself. I ordered the MegaStim unassembled kit from DIYAutoTune.com and found the service to be great.

Building the MegaStim is fairly straightforward, as long as you stick to the instructions. If you get stuck you can look at a completed picture of my MegaStim and that may help, but the instructions are quite good anyway.

The MegaStim provides power for the MegaSquirt unit, so as suggested by the MegaStim assembly page I have given it a more permanent power supply. The power supply was borrowed from a tired old Philips Windows CE based PDA, but anything that supplies 9 to 12 volts at 300 to 750mA DC is fine. Here’s a picture of my completed MegaStim with power supply:



You can use a battery for short testing but I’ve read that it will only work for a few minutes!

I will be ordering the rest of my MegaSquirt stuff next week, so I’ll post again when it arrives.

[timk]

Tonight I ordered the rest of my MegaSquirt stuff, which came to a total of US$248.75 including shipping and insurance. If you include the MegaStim (and shipping), the total amount I've spent on this so far is US$300.75. Pretty good value considering it's a standalone ECU that controls both ignition and fuel, plus other features like boost control, launch control, water injection control etc.

My order:
MegaSquirt-I PCB 3.0 unassembled kit with black case
IAC mod kit
DB9 cable
Component lead bending tool

The IAC mod kit is to control the Idle Air Controller valve on the Mazda BP engine. You may or may not need this. I also grabbed a lead bending tool to make things easier and a DB9 cable since I didn't have one spare and it will be way cheaper than Dick Smith.

Now I have to play the waiting game, I'll post here when it all arrives!

[timk]

It is here! The kit arrived yesterday (on a Saturday) which was a great surprise. I was on my way to Repco with sabretooth when I received an SMS from my wife with the good news!

I've taken a few pictures of various things, these shots will probably come in handy if I have issues and need to draw over them to point things out. I'm really impressed with how everything has been labelled, will make putting things together really simple.

[timk]

I've spent about two hours on it so far but since I'm really pedantic (and slow) when it comes to this kind of thing I'm still on the power conditioning stuff. It will start to get interesting when I get up to the serial connectivity since I get to plug it into a PC then! I'll take a picture once I complete the power conditioning section of the build manual.

For me, half the fun is the build!

[timk]

Another update! I've built all the RS232 stuff as well as everything else that is required to get the CPU talking to the computer. Here's a pic I took tonight:



Now it was time to hook up the serial cable and see if the thing worked! Pretty exciting! I fired up MegaTune and then plugged in the MegaStim, and I was presented with the following:



It works! The only correct values were battery voltage and the timer, which is completely normal as I haven't built the input section of the MegaSquirt yet (so it's showing garbage values). I also did the same test from the main MegaTune screen, the only changes made were to right-click the last gauge shown to change it to battery voltage:



The voltage reading is fine considering I'm using a 12 volt power pack. If you're just using a 9 volt battery the reading will obviously be lower. You may notice that the gauges don't mention ignition advance or anything. That's because I'm still using the standard firmware (I haven't loaded MSnS-extra yet). I will write about this when I do the re-flash.

Now to continue building this little beast, so the MegaStim actually works! Big Kev may not be around any more, but I can still say I'm excited!

[JBT]

This is fascinating stuff even though I barely understand what you're talking about saboteur . Reminds me of the time my son tried to explain some random chaos theory thing to me when he was doing his science degree.

[timk]

I decided to work on this a little bit over lunch so instead of working on the PCB, I installed the MSnS-extra firmware. It was quite an easy and fast process.

First I had to jumper the boot header. This is only required when you are running the standard version of the MegaSquirt firmware and wish to upgrade. Once you load the MSnS-extra firmware, it is smart enough to allow upgrades without the jumper. Here's where the headers are that you jumper:



I just bent an old component lead into a U shape and installed it, then switched on the MegaStim.

The next step was to download the MSnS-extra firmware. I extracted mine into C:\\efi and then ran the download-firmware.bat file. If you read the initial setup instructions, everything is fairly simple.

This is how things looked after the firmware had copied to the MegaSquirt:



At the end of this process you'll most likely get an error saying the boot header jumper is still installed. Turn off the MegaStim, remove the jumper, and power it back on. Now you are running MSnS-extra!

[phatMX]

saboteur keep the posting, i'm interested to see what you think of the computer once its all tuned and running as your daily computer. Have you got a specific tuner that has experience with this computer or you doing it yourself??

[jules]

I just LOVE this sort of stuff. Please keep going with the thread Sabs.

I'm not too shabby with a soldering iron, having made guitar effects and amps etc...I don't think I'd have the brassy's though to do an ECU. Just the fault finding if it didn't work right would do my head in. Hats of to you.


Jules

[Steve 818]

I just LOVE this sort of stuff. Please keep going with the thread Sabs.

I'm not too shabby with a soldering iron, having made guitar effects and amps etc...I don't think I'd have the brassy's though to do an ECU. Just the fault finding if it didn't work right would do my head in. Hats of to you.


Jules

Jules, if you can solder then the Megasquirt is definitely the best bang for your bucks mod around. Imagine having full control of the engine for less than $500. It makes everything else stupidly expensive by comparison and it certainly isn't short of features either.

Besides, how many people can say that they have built/modified their ECU specifically for their own needs??

Not to mention also having the ability to develop your own maps and being able to tune the ECU yourself.

There wouldn't be more than a few thousand people on the whole planet who could boast those kind of achievements.....

[The Pupat]

I just LOVE this sort of stuff. Please keep going with the thread Sabs.

I'm not too shabby with a soldering iron, having made guitar effects and amps etc...I don't think I'd have the brassy's though to do an ECU. Just the fault finding if it didn't work right would do my head in. Hats of to you.


Jules

Jules, if you can solder then the Megasquirt is definitely the best bang for your bucks mod around. Imagine having full control of the engine for less than $500. It makes everything else stupidly expensive by comparison and it certainly isn't short of features either.

Besides, how many people can say that they have built/modified their ECU specifically for their own needs??

Not to mention also having the ability to develop your own maps and being able to tune the ECU yourself.

There wouldn't be more than a few thousand people on the whole planet who could boast those kind of achievements.....

I dunno about that, a LTX8 is about a grand and will do those things, and you don't have to assemble it.

[jules]

Are you going to do a plug and play loom for it?


Jules

[jules]

I dunno about that, a LTX8 is about a grand and will do those things, and you don't have to assemble it.

I think the LTX8 has been superseeded, and doesn't that ECU require coils as well?


Jules

[The Pupat]

Yep you're right, it's LT8s now... though if I remember the X only meant it had onboard ignition igniters ... but I'd guess that's standard now.

MX5 already has coils running in waste spark doesn't it? and an LTX8 certainly will run waste spark.