[Gmecm] TBI Swap - Iron Duke Tech IV

[Jay Vessels]

Hi there!

>    The actuall installation of the manifold/TBI is nothing for me to 
> do... its all the wiring!  I took all the wiring that was attached to 
> the two plugs on the ECM (which is a 1227748).  I noticed that the ECM 
> controls the Transmission in the Oldsmobile, which I have cut off from 
> the harness... also the electic fan wiring has been cut off...

I would have kept the fan wiring in case the move to an electric fan was 
ever planned.  It's easy enough to add back in later, I guess.  Electric 
fans can help pick up a bit of power versus a clutch fan.

>    So, can I just cut and cap off the wires that I don't need?

Yes.  Make sure they don't have any opportunity to short against 
something and you'll be fine.  If there are wires going to the ECM that 
I don't intend to use, I remove the pin from the connector -- no wire, 
no chance of a short.  Removing pins from the ECM connector shell isn't 
difficult.  The pins have a tab that sticks up and bites into the shell. 
  Use a paperclip or something similar (thin screwdrivers work well) to 
push the tab down, and pull the pin/wire out.

For your setup, the transmission wiring is only controlling the lockup 
torque converter, so as long as you don't need the ECM to run the torque 
converter, it's okay to remove it.

Do you have a wiring diagram for the Olds?  If not, try your local 
library and see if they have any service manuals.  Or, go to a local GM 
dealer -- many will let you photocopy pages from their shop manuals. 
I've done this before and I've never had a dealership refuse (and many 
have copied a page or two for me for free).  That will be a great help 
getting the harness in shape.

> Tell me whatever you all know, even if it sounds stupid, lol... what 
> parts I need etc, and I'll make sure I've got everything squared away 
> before I undertake this!  (BTW, I'm hoping to do this in about 2-3 
> weeks, and will attempt to complete the entire swap within a week... 
> Like I said, once I plug everything in and plug it into the ECM the 
> thing will run flawlessly being the same engine, I'm just scared it 
> wont, lol)

I assume you still have the harness out of the vehicle -- that is, you 
haven't installed it yet.  Lay the harness out on the floor, and 
carefully remove all the wire loom and tape from the harness.  Clean it 
up, rebundle it, and go over each wire and connector with the wiring 
diagram and an ohmmeter.  As you go over it, check each connector to 
make sure that it's in good shape, and that the ohmmeter tells you that 
it is connected where you think it is.  This is also an opportunity to 
re-lace the harness and arrange it so it looks and fits better on your 
vehicle.  As you get to each connector, figure out what that connector 
plugs into, what that component does, and why you need it.  This study 
can come from any number of good books (i.e. the Helm manual for the 
donor car or one of many books on EFI), the Web, or here.

This will make your conversion take longer, so why do this?  Three 
reasons.  First, it will give you confidence that the harness is in good 
shape and that if you run into problems, it's not a fault lying inside 
the harness.  Second, if you do find a problem in the harness (i.e. bad 
spot in a wire) you can fix it while it's off the vehicle.  Third, it 
will give you a better understanding of the harness's layout and how all 
the pieces are connected.  This basic understanding will go a long way 
to understanding how a computer can run the engine, and what to do if 
you have a problem with the installation.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)