Converting to EFI from Carb - help

[steve ravet]

> Hi,
> I have a 3.4L (oversized 2.8L) in my '84 Jeep Cherokee.  Don't be
> too dismayed by the engine - everything that can work on the 2.8L
> will work on the 3.4L.
> 
> The current induction setup is a E2SE carb, part 49 state - part
> calif.  I recently obtained a 220 TBI EFI setup from an '86 Chevy
> S-10.  This includes the computer, wiring harness for entire engine
> well (firewall forward) including setup to the computer, TBI and
> intake.  I would like to switch to EFI from the carb setup.
> 
> Now the fun part.  I need to make a 'stand alone' wiring harness for
> the Jeep.
> 
> Does anyone have an exact wiring diagram for the '86 S-10 so that I
> may accurately create this stand alone harness?
> 
> How about anyone who could help me in ANY way to get this thing to
> work.

Having just replaced the engine in my '86 Blazer, with one that 
was never supposed to be in there in the first place (TBI 5.7l) I'm 
pretty familiar with the wiring.  First things first, call Helm and 
get the service manual for the Blazer and the Jeep.  They're 
expensive, but I promise you will appreciate them once you are done.  
I managed my swap using a Chiltons and an Alldata automotive CD, but 
I wouldn't do it that way again.

Now, I'm not sure why you need to make a harness since you have one 
from the engine firewall forward.  Seems like you should be able to 
bolt on the hardware, and use the S-10 harness.  I guess you'll have 
to use Chevy sensors so the connectors will mate.  The engine harness 
has a lot of wires in it, but it is for the most part "self 
contained", in that there aren't a lot of connections between it and 
the body harness.  The things that do go thru are most non-engine 
related, like A/C controls, wiper motor controls, sensors for the 
dash gauges, etc.

In the S-10, there is a bulkhead connector where the connection is 
made between the engine harness and the body harness.  I'm sure your 
Cherokee is similar.  Once you have the service manual for both 
vehicles, look at the pinouts for both connectors.  I suspect you'll 
find that they share a lot of the same signals, like fused/unfused 
power, sensors for the gauges, wiper motor controls, etc.  

For my swap, I bought a spare engine harness from the junkyard so I 
wouldn't have to hack up the original one.  I plugged it into the 
body harness at the bulkhead connector, and one by one spliced the 
wires into the 5.7L engine harness.  It'll go faster if you get the 
whole thing figured out first, then spend an evening clipping and 
twisting.  I typed the whole thing into a speadsheet, printed it out. 
 I twisted the wires together initially, to make sure the engine 
would start, then crimped them.  Other people here have said that 
they should be soldered rather than crimped, but it all seems the 
same to me.  Time will tell.

One thing I wonder about, will the 2.8 ECM be able to compensate for 
the increased flow of the 3.4?  I guess the block learn can 
compensate, but can it compensate that much?

--steve