Running a Northstar on a 1227730 ECM

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300 horses 6700 rpm redline (stock), capable of 7500 RPM with just some valve springs from chrfab.com .... Or 8500 RPM with upgraded rods. Now, the problem is one of controlling the engine. The stock computer is great, but doesn't offer you much flexibility. When you take it out of a cadillac, it is going to miss all of it's auxiliary computers (ABS, climate control, BCM, etc), plus, the stock computer can't handle major engine changes (cams, blower, etc). So you're stuck with running a Holley, Haltech or Megasquirt ECM. Right? WRONG! Aftermarket ECMs have their place, but not on a street car. If you want to read about my misadventures trying to get a Holley Commander 950 to run my Northstar in a Fiero, read here: Why aftermarket computers suck

Long story short, don't do it.

Well what's left? Anyone that's been around F-bodies knows about the 1227730 ECM. This is the computer that runs the speed density small block chevies (and pontiacs, heh). They're everywhere, well hacked and documented, and cost you $20-50 in a u-pull-it yard. Even the megasquirt can't compete with those prices. Plus, when you're stuck in BFE because your computer blew up, the chance that there is a 1227730 within 10 miles of you is almost 100%. A megasquirt? 0%. So that's part 1 of the story.

What do I need?

-A 1227730 ECM (Used in:

   1987-88 2.0 L4 TBI 
   1987-89 2.8 V6 PFI “W” LB6 (exc. “W” body) 
   1988-94 3.1 V6 PFI “T” LH0 (exc. “W” body) 
   1990-92 5.0 V8 TPI “F” LB9
   1990-92 5.7 V8 TPI “8” L98 (“F” body))

-A memcal from a 2.8 or 3.1L V6 (all aluminum - i.e. from a FWD car, not RWD)
-A memcal adapter, or patience to install a chip socket.
-A 29C256 or 27SF512 flash EEPROM "chip"
-An EPROM burner
-Tuning Software -Definition files for the northstar chip -Northstar binaries -A 7.5K resistor

First, we need to install the tuning software. Tunerpro RT is highly recommended. It is free with a suggested registration of $30. Please register it if you find it helpful!

Next, download the definition files here.(rename to .xdf) This file allows you to edit the binary (chip). Things like rev limiter, ignition timing, fuel curves, speedometer calibration, all the good stuff is user editable.

Now you need the northstar calibration here. This is the custom program that will run your northstar. Many, many, many many many man-hours went into this program. I programmed literally over a thousand chips to get to this point. Sometimes I thought it wasn't going to be possible to run a Northstar on a '7730. Please, do not download this and sell it on ebay. In fact, don't sell it at all. If you have something cool you're working on and want to sell this as part of your sand rail, please contact me first.

I won't get into tuning here. That's a whole 'nother website. Just know that the stuff above will run a 96-99 northstar (93-5 with mods) just fine without any need for tuning. However, perhaps you have cams or something that requires custom tuning. That's possible with this system, but I'll leave you to figure that out on your own. You will need the ALDL file (rename to .ads) so you can get a laptop to communicate with your ECM.

Okay, so you customized your binary to your engine (or not). Now what? Now you need to install it on your EEPROM chip. The 29C256 from Atmel were great. They programmed perfectly every time. Then Atmel discontinued them. They're now impossible to find. So us tuners had to use something else for our custom chips. The 27SF512 is a good replacement. I sometimes have problems writing them, but it could be a problem with my Willem Eprom burner, not the chip itself. I don't like them, but it works because the chips are cheap.

Here is the Willem EPROM programmer:

It is powered by USB and costs about $30 on ebay. Dirt cheap!

You plug your chip in there and use the software to write the binary on the chip. If you are using the 27SF512, make sure you change the "offset" to 8000. This is because the chip is actually twice as big as needed, and you just need to write to the last half of the chip. That's the cliff notes anyway... You'll need to modify your memcal to accept the new chip (or use an adapter from moates).

Update! Links to the wiring diagrams:

Page 1 wiring diagram
Page 2 wiring diagram
Page 3 wiring diagram

Last update: 2/22/09

(C) Copyright 2009 Ryan Hess. All rights reserved. Information NOT FOR RESALE!