Break out the soldering Iron!

I just ordered up a full megasquirt 2 kit for the SRT-4 powerplant that is destined for my Midlana.

I'm thinking that after I build and test the megasquirt with a stimulator I will try wiring it up to the engine and testing/rough tuning it on a stand before I install it (or start building) the car. Any reason not to? I'm excited, and a bit intimidated, by this part of the project.

Make sure the stand is sturdy (i.e. not a standard engine stand) and it should work, but the required components to provide fuel, coolant, etc. to the motor should be provided in a safe manner.

Is it a PNP kit or is it a generic standalone?

If its Generic, I'd spring for the relay board, I wish I had as it makes things so much easier to wire up, especially in combination with with the DIYAutoTune labeled wiring harness.

Biggest thing to remember? Go slow and make sure your solder is the proper type, clean the soldering iron tip often. A helping hand tool, especially one with a magnifying glass helps quite a bit.

Good luck!

bgkast wrote: ...I will try wiring it up to the engine and testing/rough tuning it on a stand before I install it (or start building) the car. Any reason not to?

You probably won't have any means to put load on the engine, so you'll be very limited in what you can tune (essentially, you'll only be able to tune the idle and a small zone on the fuel map where there's no load on the engine). I don't know that it's worth the time to set up the fuel system, cooling system and engine stand just for that.

I would strongly recommend against the relay board. There isn't much it does for the extra harness it needs. Just wire direct and add the two relays you need.

I wouldn't bother with running it on a stand unless you want to test something mechanical on the motor itself before you drop it in. Seems more hassle than it's worth.

Paul_VR6 wrote: I would strongly recommend against the relay board. There isn't much it does for the extra harness it needs. Just wire direct and add the two relays you need. I wouldn't bother with running it on a stand unless you want to test something mechanical on the motor itself before you drop it in. Seems more hassle than it's worth.

Really? After dealing with fitting the extra relays and fuses into my own install, the relay board looks to make more sense, but I'll defer to your experience on that one.

I agree on the relay board. I have installed nearly 10 MS systems. I use my own relay and fuse block systems.

Paul_VR6 wrote: I would strongly recommend against the relay board. There isn't much it does for the extra harness it needs. Just wire direct and add the two relays you need. I wouldn't bother with running it on a stand unless you want to test something mechanical on the motor itself before you drop it in. Seems more hassle than it's worth.

I agree with this, having 3 MS'ed vehicles, including the one I drove to work today.

The double ended cable, relay board and wiring bundle seemed $$$$ to me. I plant to just grab an appropriate looking (and hopefully watertight) fuse/relay box from the junkyard and use it.

I don't need to test the engine, I drove around the block in the donor before I pulled it. How well do the stimulators work to test out the system? Since I have a few months before I get the plans to the car I thought I could keep myself busy by building, programming and testing the megasquirt system.

Stimulator works fine for testing. Just go through the build manual and test it along the way like it says.

On the other hand I have done 4 ms installs and covered 30k miles of daily driving and always use the relay board.

I like the silly thing. Absurdly simple to wire and makes troubleshooting a breeze since everything is labeled.

I made this adapter to mate a generic MS2 to my Festiva powered Miata.

The adapter allowed me to use the existing relays already in the car.

If you are scratch building a full harness then you may find the relay board to be easier.

Getting the engine to run on a stand has some benefits but overall you are limited to the amount of tuning you can do.

Good luck with the MS build!

So many blue wires!

I ordered the 12' harness. I figure I can use about 6' or less of it to run to the "junkyard" relay box and another 6' from my relay box to the engine with the same wire colors. It probably would have been easier to just order the relay board, but I could not bring myself to order a $73 relay board, $85 relay cable and $46 wiring bundle, when I can get about the same effect with the $85 12' harness a $10 fuse box from the junk yard and an extra hour or two of time.

I'm trying (poorly) to stay on a challange budget here!

In use these in a lot of installs. 2 for simple installs and the 8 for race cars, including mine:

http://leashelectronics.com/Relay-Boards_c5.htm

Don't knock the all blue wire as long as you lmow whats going on and can troubleshoot it. I have used all white aircraft grade wire before. You just need to keep things labeled and straight.

Not knocking it, just know that if I tried it I would end up getting things crossed up!

He he he I did a Porsche wiring from a MS2 to a DME connector and lets just say it gets complicated. You first have to figuar out learn how the OE system works and is wired. Then figuar out what has to attach to what to make ti work and what you have to custom wire. If I was to do it again I would probably just get a made up harness from DIY and not use the OE but it taught me more than I ever wanted to know about the engine management of a 944.

It works but I use a lot of brain cells.

This

resulting in this

I did not use a relay board because I am running through the OE one where needed (power etc). I also down the road found that the whole putting of resistors in line with the MS is a wast of time. Just load limit the Injectors with the MS. In short the two gold resistors in the photo were eliminated.
For those trying this or if some one down the line is goggling and finds this. It is for an 87 924s that I am running a 72-2 cam fired EDIS based ignition system with it and the stock TPS was removed and replaced with one from a 951 that is used in conjunction with MAP. I am also running a GM IAT and eliminating the stock AFM. Use at you own risk!!! (and I thought this was going to be a plug and play deal LOL)

Regarding the stim... GET ONE!!!! Put it together first. It is good practice for when you solder the MS together. It is also invaluable for testing your MS as you go along. Did I say GET ONE? Ohya GET ONE !!!!!

This is important as well. Get a small 10-12 wat pencil soldering iron. The 20-30 wat ones will damage things / burn the board / burn components. Seriously this is a case where smaller is better. You want a surgical tool not a hammer.

Get solder that is fine I like the .025" (23 ga) solder. The standard radioshack stuff is just to thick. (Again think surgical tool)

Have fun you will learn a lot. You will also start wanting to solder other things together. After my MS I built a AM/FM radio and a couple other LED blinking things with my son.

I just got a big box from DIY autotune! I got the JimStim simulator kit that I will put together first.

Paul_VR6 wrote: In use these in a lot of installs. 2 for simple installs and the 8 for race cars, including mine: http://leashelectronics.com/Relay-Boards_c5.htm Don't knock the all blue wire as long as you lmow whats going on and can troubleshoot it. I have used all white aircraft grade wire before. You just need to keep things labeled and straight.

Oh damn. Those are kind of slick....

Agreed on labeling. As long as it is labeled, one or two colors is fine over short lengths.

Paul_VR6 wrote: In use these in a lot of installs. 2 for simple installs and the 8 for race cars, including mine: http://leashelectronics.com/Relay-Boards_c5.htm Don't knock the all blue wire as long as you lmow whats going on and can troubleshoot it. I have used all white aircraft grade wire before. You just need to keep things labeled and straight.

First time I cracked into an olde tyme Porsche 914 FI harness every damn wire was white. Turns out Bosch uses connector cavity numbers instead of color codes.

I have done the Vulcan mind meld on a few EFI harnesses, last one was a hybrid S4/S5 13B harness. I used the cavity numbers instead of the color codes on those, made some notes for future reference.

For you experienced ms guys, I did one car with a microsquirt, so just had to make wire connections. What's the advantage of all this extra work?

The kits are about $100 cheaper than the assembled units, plus I think it will be fun to learn about the system as I assemble it.

icaneat50eggs wrote: For you experienced ms guys, I did one car with a microsquirt, so just had to make wire connections. What's the advantage of all this extra work?

Slightly cheaper, and it's a learning experience - if that's what you value. You can also get a bit more inputs and outputs off a customized, kit built MS2. If you don't need a ton of I/O, want something cheap that is ready to wire up out of the box, and want simple - MicroSquirt is a great route. B&G marketed it towards the powersports crowd, so a lot of people expect it to only be for bikes and ATVs - but it's a great automotive ECU as well, and can work out to be cheaper than an MS2.

Agree on the relay boards being mostly for cars that weren't wired for EFI from the start. They're a bit of a judgement call. I usually recommend them for street rod type applications, not so much for modern cars that already have the relays and fuses to support EFI.

That would explain that. I have only squirted cars like my 71 fiat or diesel and CIS VWs from the late 70's. I plan on slapping a relay board into my 63 Falcon too.

When I squirted Dr.Linda's Sportster, all I had to add (electrically) was a fuel pump relay and a couple fuses.

Oh, the DIY labeled harness rocks. Pick up a wire, read where it goes, run the wire, solder, heat shrink, pick up the next wire.

Dr. Hess wrote: Oh, the DIY labeled harness rocks. Pick up a wire, read where it goes, run the wire, solder, heat shrink, pick up the next wire.

This!!!!!

Haven't done a MS (although that should change soon) but I am a big believer in taking whatever load I can off of a circuit board. That's why I like using relays for higher amp draw stuff, that way if something shorts the relay takes the butt whippin' not the circuit board.

Like this: a fuel pump might only draw, say, 5-8 amps. So a circuit board can easily handle it- UNLESS the pump decides to seize. Now my 5-8 amps jumps to 30, 40 or even higher and now I have to replace a (possibly custom built, maybe low production) circuit board. OTOH, if I'm using a relay to isolate the pump now all I have to replace is a fuel pump and a $6 plug n' play relay. Yeah, I'm a cheapskate.