I am going to be running a GM250 I-6 in a rockcrawler project of mine in the future. This motor will need to run EFI and I have been looking at the megasquirt setup using a stock GM TBI.

The motor will be mildly hopped up. Intake, header, cam (260H).

So what I am reading is you add the megasquirt in with the stock GM computer to make it programable and tuneable is this correct? So what all will I need with the setup on the Megasquirt end?

I know I will need the GM TBI setup from a 88-92 4.3L V6 but will I just need MS computer to piggyback the GM comp? I am not new to EFI just Megasquirt. I did a TPI conversion on my 85 Blazer offroad truck already so I understand the mechanical end of the EFI install just not the megasquirt side. Thanks

Harley

Harley,

"So what I am reading is you add the megasquirt in with the stock GM computer to make it programable and tuneable is this correct?"

Correct!


You will need the following MS parts:

1) MS V3.0 main board
2) MSII processor
3) MS to GM tbi adapter board
4) laptop to tune with.

Also you will need a junk GM ECM from a '88 to '92 GM truck last 3 digits in the ECM part number are 747 . You will reuse the GM case and ECM connector from the GM ECM - the stock GM ECM board gets tossed once you have got the connector and heatsink removed.

Check Scott's site for instructions on getting the ECM connector off of the GM board - it show a ford eCM but the process is the same.

http://megaefi.com/

To get the MS parts except the MS to GM tbi adapter board look here: http://www.megamanual.com/v22manual/mintro.htm#group and click the purchasing link. I use Glen's garage but its up to you.

I will have the MS to GM tbi adapter boards available real soon (within a couple of weeks).
Email me at ca434sbc4@yahoo.com when your ready.
Pix are here : http://www.msefi.com/viewtopic.php?t=25391
I'm working on a mini version that is a lot simpler - I'll have pix of the mini version next week.
The harness can come out of any '88 to 92 GM truck that used TBI.

Hope this helps.

Here is a pix of the 1st GM TBI to MS adapter board with the megasquirt board installed inside the stock GM case. I needed to move 2 mounting holes -nothing a 1/8 drill won't fix...


By efi_diy , shot with u710,S710 at 2007-07-10
URL=http://img412.imageshack.us/my.php?image=p7100022pg6.jpg] [/URL]


By efi_diy , shot with u710,S710 at 2007-07-10

If your running a manual transmission or non lockup automatic transmission then the only parts that need to be added to the board are 2 resistors and 1 diode. I'll install these tomorrow.

So the parts that get installed for a manual transmission or non lockup automatic transmission are:
The GM connector
the megasquirt connector
2 relays
2 resistors
1 diode...

for a lock up automatic add:
1 transistor
2 more resistors.
1 more diode

Assembly time for the adapter board is 30 min's for someone who has built an electonics hobby kit before and most likely 60 min's for a newbie. Its really not that hard.

M.

So you only need the GM case and connections and NOT the ECM board. <<<< correct the GM ECM board goes into the garbage once you have the connector removed.

What about controlling the 4L60E Trans.?

If you want to control a 4L60E transmission then you need to use the other board I have ready and posted about a few weeks ago. The smaller board posted above only has enough capability to do the EFI and t/c control. I did this board for folks who have a 700R4 aka 4L60.

The transistor and 2 resistors are for converter lock up on 350 Lockup, 200-4R or 700-R4, right? <<< Correct!

EFI for the masses