Megasquirt FI info

I thought since there were many looking at the megasquirt perhaps a topic with some tidbits of info on the system might be in order. So instead of hijacking the other threads I'd start this one. I found this while looking at the www.msruns.com forum. That forum is for projects using the MS that are running and there are quite a few projects of all different makes, models and even some peculiar engines running it. Its well worth a look. I'm doing this mainly as a hobby right now, I don't have the funds or the health at the moment to do more than try and dig up information (I'm home bound so I do have plenty of time), but I do hope to get one of these up and running someday hopefully in a CJ with a Dauntless. Here is a wiring diagram I found, I'm assuming its for a four cyl because of the obvious 4 injectors (this appears incorrect, see next msg). But it'll give an idea of how the system works somewhat. I have no affiliation with MS just feel its probably the cheapest way to go and appreciate the grassroots hobby nature of the unit.



Regards,

Don

Ps: Much of the info here is for more the DIY/Fabricator/Experimenter mechanics in the crowd and might be dry reading for those looking for kits, but here it is, bad or good.

 

Further looking at the diagram, it appears you'll see the arrows pointing away from the injectors, I believe you can us as many injectors with the diagram as you like and then its just a matter of telling the Megasquirt on the laptop how many cylinders your using. Thats just from the looks of things. When I find out more I'll let you know. I can tell you there are at least two or three CJ's on the above forum running the MS with a odd fire Dauntless, so those looking for info might want to contact the owners of those projects. I'll post some info if I have time on what they may have listed. I think many of them are running the MSD6AL.

Regards,

Don

 

Here is the web page with the Manuals for the MS, might answer some questions or give an idea whats involved:

http://www.megamanual.com/mtabcon.htm

Regards,

Don

 

Here are some step by step articles from the MS guys that might help you out. I hope I'm not making a nuisance of myself here with all this:

http://www.diyautotune.com/tech_articles/megasquirt-carb-to-efi-part1-nova.htm Carb to TBI

http://www.diyautotune.com/tech_articles/megasquirt-carb-to-efi-part2-nova.htm Ignition Control


http://www.diyautotune.com/tech_articles/megasquirt-carb-to-efi-part3-nova.htm TBI to Multiport

 

Ok guys, I spent this evening looking at the carb to TBI link in the above post and I'll tell you, once you get the thing mounted and the relay board in the engine compartment, with that pictorial I can't see how the average mechanically inclined guy couldn't do this. I'm also thinking that even if you bought all the sensors new and the fuel pumps and pick and pull the TBI unit and stuff outlined in the above link with a prewired MS unit and the relay board that this is going to be WAY cheaper than some of the kits. No not as easy and please understand I'm not against anyone that can afford the kit and doesn't want to hassle with all this going that route. What I have here is how I'd do it being relatively poor (at the moment even officially at poverty level not to cry a sad song, just like many right now the truth).


I'll try and price out what they have going on here when I have the time just for yucks to see what it truly cost, but I'd bet about a grand or so (and I could be way off base here, as I say I'll try and price it out if I'm able just to see). I know thats still pretty pricey but considering the advantages in fuel control and mileage and in the long run a motor that will last longer its worth it.

An interesting bit I'm still reading on and just to a break to post this, in the set up software getting ready to start the engine, you basically configure a few base questions, burn the setting to the ECU using a laptop and then your ready to fire and tune from there. In the windows table in the setup menu are a few items you need to fill out. One of them number of cylinders, and number of injectors, they have 6 set which I'm assuming is for a multiport, this would change to 2 for TBI but more interesting, look where it says engine type and displayed with a drop down is Even fire, hmmm wonder what is in the pull down, one can only assume Odd fire!

So the question to get answered still is will the HEI tach signal give the correct info. I'll try to see if I can find that info, I'm assuming it must be possible as several are running the TBI with the dauntless motors. They do mention using shielded cable at this signal point and its obviously for noise reduction so it gets a good clean signal (as a sidebar, I build guitar amps for myself and in tube amps, shielded wire is usually always a good idea from the input to the first tube to reduce noise, so I'm familiar with why its done). Here is the table I was referring to in the configuration menu of the MS programming done prior to starting the engine:



Regards,

Don

 

At the end of the article, it gives what he spent on the components and of course there is a wide variation of what some things are going to cost. Filters pre and after pump were nearly 200.00, I think there are probably some places like that, that could be shaved, I seriously doubt GM used 200 bucks worth of filtering. The MS shows a assembled price of 405 bucks, probably can be found cheaper. There are a few items where you just probably aren't going to get by much cheaper, but I'll (or We'll you want to get involved right?) see what we can do with a sharp pencil to get the numbers down a bit. Oh well, insomniac me headed to bed finally nearly 4:00 am my time. Take care.

Regards,

Don

 

I spent $750 total on the MS I was running on my 258 w/GM TBI.

That is after having to buy the computer 3 times. I built my own and the first one died from a known issue with running low impedence injectors without flyback protection (Ver I board) and the second was because I installed a Diode backward during the build and shorted unfused 12v from the tach input straight to ground (Ver II board).

It is not difficult to do at all. Just take your time and read the manual several times before you start.

It does not matter how many injectors you run. I think the current system can run up to 12. And the number of injectors have no corrolation to the number of cylinders. Ths is why the GM TBI can work on virtually any engine.

 

BTW: The drop down will let you select odd-fire. This puts the computer into a mode where it averages the pulses coming from the tach to determine the engine RPM for the fuel calculations.

The problem with the odd-fire is if you intend to run your ignition timing from the MS. If not then it should work just fine.

 

I've been running megasquirt on my VW for about three years now. It's a pretty slick setup. I've just finished setting up to run "coil on plug" so no more plug wires even. It's pretty fun, but it is a LOT more setup work than just throwing on a carb. But in my opinion, worth it.

 

Thanks guys, I appreciate the info, I think if more people understood the MS a bit better they'd be less on the fence about using it. Although I haven't installed one, I'm no stranger to EFI and am pretty comfortable with it.

Hudson, I'm glad to see a number on what it cost you, I was thinking for around that it could be done, but didn't want to say it without confirmation. Boy do I know the feeling of putting components in a boad backwards. As I mentioned I build tube amps and on more than one occasion have I put things backwards, wired something wrong or put something of the wrong value. The deal with Amps though is its high voltage and they don't always take kindly to it, I've had some pretty good flashes and explosions. (I'm sure that 12v straight to ground was exciting though, a lot more amps than I mess with haha) Heh. Anyway thanks for the reply, much appreciated.

Thanks again!

Regards,

Don