Hi all, I just put an LO3 in an Astro. THe problem is I was told that I would need to change from a 7137 to 7747. could you just change the chip instead? or would you have to change the ecm's. I'm trying not to have to change the wiring on the plugs to make it work.
Thanks DksAstro

 

Just double checked. The program is different between the 7137 and the 7747 or a 8746. The chip will not change over. If it won't run with a good 8746 ECM, it isn't going to run on a 7747. You have two options from here. Reprogram the ECM using 305 parameters, or change a couple of wires around. It looks like the early 4.3 ECM uses different pins for the injector drivers. The 8746 and 747 drive the injectors on pins D14 and D16. The 7137 appears to drive them on C15 and D15. Check to be sure you have a Blue wire in D16 and a Green in D14. Looks like they are currently Blue in D15 and Green in C15. PS, the connectors are labeled A, B, C, and D. Here is a pinout for the 7747.

ftp://ftp.diy-efi.org/pub/gmecm/manu...47/747ecm1.jpg

Here are the 8746 camaro ecm pinouts.

http://www.diy-efi.org/gmecm/ecm_inf...6/89FTBI_4.JPG

 

THANKS! You make it sound like it won't be too bad to do.
I called the local junk yard and can get a7747 for $30.00
which don't sound to bad.
Thanks for ALL your help, I was looking at your spec's on your van,sounds pretty cool,probally alot of fun to drive!
I'll be happy to get this running right then I can start thinking of upgrades[maybe]. There's alot to learn.
Thanks again
DksAstro
P.S.
thanks for the pin out diagram,I owe you a cup of coffee or something

 

Thanks for your help 355, I went and got a 7747 made sure all the wires were right and it fired right up! Runs allot better now and even found a vaccum leak I didn't know about before.
Thanks Again DksAstro

P.S.
do you know anything about the claims that those tbi spacers, do they increase torque and h.p.?