Engine swap computer & wiring question

[Tim De Coster]

Well... I thought about it, but figured the tranny I have now would be
easier to work with.  I don't mind the automatic transmission.  I have had
no real problems with the 125C.  I have one in my Z24 with 185,000 miles on
it, and it still has no problems.  The one in question is in my Sunbird, and
has 102,000 on it, and with a rebuild it'll be good as new.  This is the
same engine that was used with the Sunbirds that had the turbo and that put
out 165 HP from the factory, so a few extra HP shouldn't hurt it.  The guys
on my v6jbody list kind of persuaded me to shy away from the electronically
controlled transmissions, because there is question as to whether or not it
will physically bolt in, and nobody has had any serious trouble with an auto
tranny - they will stand up to a quite abit of punishment.  There is a guy
with the manual transmission on the v6jbody list who has a modified turbo
3.1 and the stock manual transmission is holding up fine, the same is true
with another guy with a supercharged 3800 in a z24.

My question is more with the computer programming end of things... I think
with enough time and right manuals I'll figure all the connections out.  My
biggest concern is will the 3.1 computer control a 3.4 engine.  There can't
be TOO many differences, and if they are, can the EPROM be re-flashed.
Also, in what ways might the programming be different?  I know of the
obvious difference with the fuel injection.  the 2.8 is MPFI and the 3.4 is
SFI.  I'm told that the OBDI computer isn't advanced enough to handle the
batch program to run in SFI.  Can the injection timing, spark advance, etc
be changed?

Thanks again,
Tim De Coster
'89 Z24 Conv.
'88 Sunbird GT Conv.
'98 Intrepid
www.sunbirdconvertible.com


----- Original Message -----
From: "Bruce Plecan" <nacelp at bright.net>
To: <gmecm at diy-efi.org>
Sent: Wednesday, July 12, 2000 2:08 PM
Subject: Re: Engine swap computer & wiring question


> Subject: Re: Engine swap computer & wiring question
>
> Somethings to look at:
> The 96 uses a pcm.
> They control the powertrain not just the engine, as in tranny shifting,
do
> you think the oem tranny is going to last with this new engine?.
> I'd think about going engine and tranny,  then just use the harness as a
> whole,
> For the dash end of it ya need to get the manuals and see what hooks to
who,
> and then what signals they are to see if they are the same.
> If you go to a manual tranny was that an option with that engine?.  If not
> you might spend some serious time getting things running right.
> Any thing is possible, just some things not practical.
> Man gotta know his limits, and then work on em.  ie, get all thenfo you
can
> (like your doing, but gotta dig for as much as ya can)
> Grumpy
>
>
> > Steve,
> > Thanks for the tips.  Man, that Blazer must fly!  The reason this swap
may
> > get a little bit hairy is because I don't think I'll be able to use the
> > entire harness out of the donor car because it will be an OBDII
computer,
> > and from what I understand, it's not easy to get a OBDII computer to
> > function in an older car.  So do you think that my existing computer
could
> > control this new engine if I get a new EPROM module for it?  I already
> have
> > one from a '91 Z24 (It had a 3.1 v6), and I am hoping that it will work.
> It
> > may because the 3.4 is basically the same exact engine as the 2.8,
except
> it
> > has revised heads, among a few other things.
> >
> > I know that the Cadillac Cimarron's digital dash does talk to the ECM,
> > because I was going to put the Cimarron digital dash into my Sunbird...
> > until I found that most of the info. for the gauges goes through the ECM
> > before it gets to the dash.  This probably would mean that the Cimarron
> > wiring idea is out of consideration, right?  The only reason I thought
of
> it
> > was because the dash is physically the same in it, and it has a 2.8 mpfi
> v6
> > engine.
> >
> > I'm not sure exactly where the vss signal comes from in the Sunbird, I'm
> > still working on getting a GM manual for this car.  I know that the
> digital
> > dash in my Z24 does, but that's a different application.
> >
> > Thanks again,
> > Tim De Coster
> > '89 Z24 Conv.
> > '88 Sunbird GT Conv.
> > '98 Intrepid
> > www.sunbirdconvertible.com
> >
> >
> > ----- Original Message -----
> > From: "steve ravet" <sravet at arm.com>
> > To: <gmecm at diy-efi.org>
> > Sent: Wednesday, July 12, 2000 12:31 PM
> > Subject: Re: Engine swap computer & wiring question
> >
> >
> > > Tim, I'm not familiar with those models, but I have been through an
> > > engine swap (replace 2.8L w/ 5.7L in my Blazer).  What is the concern
> > > with the dash?  Is it electronic, and wants to talk to the ECM to get
> > > MPG info or something?  If not then I don't think it matters too much.
> > >
> > > I'll talk about my swap some, it's probably similar to what you'll
> > > find.  There are two places where wires cross from the engine
> > > compartment to the inside of the vehicle.  One is the ECM harness,
which
> > > runs from the engine thru a hole in the firewall to the ECM behind the
> > > dash.  This bit of wiring is almost completely isolated from dash/body
> > > wiring.  Exceptions that I can recall are ALDL signals like data, TCC,
> > > etc. that have to run over to the ALDL connector.  VSS also comes from
> > > the dash in my app, not sure about yours.  Anyway, as long as you use
> > > the ECM that comes with the engine there is no problem here, just
splice
> > > in the handful of wires for ALDL/whatever and the rest plugs right up.
> > >
> > > The other connector is the bulkhead connector.  The car side is
anchored
> > > to the firewall, the engine side comes from the engine bay.  When you
> > > get your new engine it'll have it's own bulkhead connector, and there
is
> > > basically no chance that it will plug directly into the existing car
> > > half of the plug.  Wires and signals here can be different even on the
> > > same year model cars, depending on options etc.  Fortunately there is

> > > little/no engine wiring through here.  Typical things here are wiper
> > > controls, A/C controls, power to and from fuse box, engine sensors
that
> > > go to dash gauges (but NOT ECM sensors, they are in the ECM harness),
> > > etc.
> > >
> > > What you'll have to do is go to the junkyard and buy an engine side
> > > bulkhead connector that is physically the same as yours (from the same
> > > model car), and all the wires attached to it as long as possible.
> > > You'll cut off the bulkhead connector from the new engine, and connect
> > > the wires to the appropriate places on the junkyard bulkhead
connector.
> > > Use crimps, and then solder them, like the service manual shows.  The
> > > junkyard connector may have blank places in it where yours has wires,
in
> > > that case you'll have to add pins and wires.  You could re-use your
> > > current bulkhead connector but I wanted to leave the old engine as
> > > intact as possible so I could sell it.
> > >
> > > You'll need a service manual/schematics for both the donor engine and
> > > your car to properly match these up.  I spent probably 20 hours or
more
> > > sitting in front of the computer, going over the schematics, typing in
> > > what went where, and double/triple checking all of it.  Then I printed
> > > it out and started cutting and twisting wires together.  I wrapped all
> > > the twists with bright green electrical tape.  Lots of time but I had
no
> > > wiring errors to track down later.  Once it's working, take off all
that
> > > green tape, crimp and solder the wires properly, put them back in the
> > > loom, tape it up nice, and off you go.
> > >
> > > All bets are off if the dash wants to talk to the ECM via ALDL,
though,
> > > like the digital dash vettes did.  hope yours isn't like that.
> > >
> > > You'll make the swap easier if you get the new engine intact with all
> > > it's wiring, accessories, sensors, etc.
> > >
> > > write back if you have more questions.
> > >
> > > --steve
> > >
> > > Tim De Coster wrote:
> > > >
> > > > Hello,
> > > >
> > > > I'm new to this list, and have to admit that much of what goes on
here
> > is a
> > > > little over my head.  I do however, have some advice to ask for.
> > > >
> > > > I have an '88 Sunbird GT with a 2.0 OHC non-turbo engine and am
> > eventually
> > > > going to install one of the '96+ 3400 OHV v6's.  My question is:
what
> > is
> > > > the best way to handle the wiring and computer change-over?
> > > >
> > > > Ways I have thought of:
> > > >
> > > > Getting the complete dash wiring and engine wiring from an '87 or
'88
> > > > Cadillac Cimarron (it had the same style dash and a 2.8 mpfi v6
> engine).
> > > > This way I would have the v6 wiring that I need, though the computer
> > will be
> > > > programmed for the 2.8.  I think it would work, but I'm not sure in
> > > > real-life what sacrifices would have to be mad going this route.
I'm
> > sure
> > > > that I would have to run the engine in MPFI mode like the 2.8 is,
> unlike
> > the
> > > > SFI mode that the 3400 was built for.
> > > >
> > > > Another idea was to use the existing dash wiring and computer that
is
> > > > currently in my Sunbird and getting the wiring out of a '91+ Chevy
Z24
> > that
> > > > had the 3.1 v6.  I would then have to change the EPROM, but I'm not
> sure
> > if
> > > > the engine wiring will plug right into the existing harness and
> > computer.  I
> > > > think the computer itself is the same, but this isn't confirmed.
> > > >
> > > > Getting a computer for the '96+ GM minivans or other GM vehicles the
> > 3400
> > > > came with is probably out of question because they use the OBDII
> > computers
> > > > which I understand are a pain as far as engine swaps are concerned.
> > > >
> > > > Any comments or suggestions on this would be VERY appreciated!
> > > > If you're interested, check out my website listed below.
> > > >
> > > > Thanks in advance,
> > > > Tim De Coster
> > > > '89 Z24 Conv.
> > > > '88 Sunbird GT Conv.
> > > > '98 Intrepid
> > > > www.sunbirdconvertible.com
> > > > www.z24convertible.com
> > > >
> > >
> >
>
> --------------------------------------------------------------------------
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> > >
> > > --
> > > Steve Ravet
> > > steve.ravet at arm.com
> > > ARM,Inc.
> > > www.arm.com

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