Megasquirt Build

Re: TBI thoughts!

In addition to the Moates APU1 AutoProm option a person may want to look at the Burn2 and a HDR1 adapter which only costs substantially less. This is what I have. I have been able to satisfy all of my programing needs with these units.

http://www.moates.net/burn2-chip-programmer-p-197.html

http://www.moates.net/hdr1-memcal-header-p-52.html

 

Re: TBI thoughts!

http://www.moates.net/burn2-chip-programmer-p-197.html

http://www.moates.net/hdr1-memcal-header-p-52.html

 

I built the stimulator on a scrap of vector board. I found almost everything I needed in my junk pile, including a 9V DC wall wart (not seen). There is a Stimulator V1 and a Stimulator V2, both schematics are on the MS site.



Here's my stimulator hooked up to the MS1 on a 2.2 board. Above it is the MS2 on a 3.0 board. Yes, I built one of each. The plan is to use the MS1 on the J10 to make a working system as cheaply as possible. I will use the MS2/3.0 on the CJ-6.

The schematic for the V1 Stim I built using a NE555 timer is here: http://www.megamanual.com/v22manual/v1stim.htm Pretty sure all I had to buy was the PN2222 transistor. If you don't have a lot of resistors, LEDs and pots lying around, it's probably no cheaper to build as to buy the kit.

I used the DB37 male connector from the kit (meant to go to the engine), so I ended up short the male half of the DB37 when i go to install. They aren't cheap - I think another one was $15 from Mouser. If you don't care about ever using the Stim again, you can test and then unsolder and use the same connector for your Jeep.

You can build the relay board pretty easily. Here's my version -

 

Well, if I were going to run a fuel-only system on a 225, I would build a MS1/2.2 for about a hundred bucks less than the MS2/3.0.

The main drawbacks to the MS1/2.2 will be no support for the stepper motor IAC valve on the ubiquitous GM/Rochester throttle body, and no drivers for low impedance injectors. The coarser fuel table seems to work fine in practice, and you can add either resistors to your injectors or build a driver circuit if you need it. The diagram for the driver board to go with the 2.2 board is given on the MS site.

You can work around the lack of IAC motor support by either picking a TB that does not have the stepper motor (ie the Ford CFI TB) or us the GM TB and add an external IAC valve.

You can see that the 2.2 board is a lot simpler than the 3.0 board, with a much lower parts count. The premium between the 2.2 and the 3.0 board is $50, and the difference between MS1 and MS2 is $60. If you get the 3.0 board, support for the GM IAC and the driver circuits are included.

 

Mmm. I think I wrote that wrong. I believe the GM IAC support comes with MS2, and the injector drivers (flyback support) comes with the 3.0 board. I can check the Megasquirt site.

Yes - http://www.megamanual.com/ms2/IAC.htm

And http://www.megamanual.com/v22manual/minj.htm#fb

Note that MS1 does support an on-off idle valve, just not the stepper motor that is used in the GM throttle body.

If you have questions I'd be happy to answer them if I can - I could say more.

 

Looks like a good start!

I'd grab the CTS (coolant temperature sender) too, if I could get it thrown in. You are going to need one for the coolant and one for the intake air. The GM air filter should have some provision for an IAT sensor, though I'm not sure what it looks like. That may work fine, but IIRC they are much more expensive than the CTS, which also works for the IAT with Megasquirt.

What do you plan for an adapter? Is Mike in production yet?

 

I don't know what the 3-wire sensor is.

If you scroll down about half-way here, the specs for the temperature sensors are given - http://www.megamanual.com/v22manual/mwire.htm

They show a 2-wire sensor for both. I picked up a couple of them and their connectors from GM TBI cars at the pick-a-part. One turned out to be broken, so I bought one new one and am using one for IAT and one for CLT (aka CTS). Apparently all the GM temperature sensors have the same characteristics. You could test your existing temperature sensor at a few temps to see if it has the same curve (likely), but if it's currently driving your temperature gauge, you cannot simply parallel the Megasquirt and the gauge and expect it to work. The input impedance of one will affect the other, and they will both be wrong. Instead, you'll need to find a place for a sensor spectifically for the MS input.

 

Yes it does. However, making spark control work for an odd fire engine would be difficult.

 

Your profile says Hurricane. I was assuming that you want to put this on a Dauntless 225.

 

The board does not know how to advance and retard the timing for the changing firing angle of the Dauntless. It can average the spark rate to adjust fuel for RPM, but it needs to look ahead to the next firing angle to calculate the advance. There is no support anywhere for odd fire spark control, AFAIK. Fuel only is it.