[Gmecm] Vortec swap info needed

Wed Sep 14 05:01:07 UTC 2005

Beau,
	I disagree that you want a manual trans bin.  The ECM does
communicate with the 4L60E or 4L80E, but if that communication isn't
done right I think it just throws codes.  I have been helping a friend
put a vortec into an '84 Suburban with a TH400, so hopefully next week
I'll have some more information.  In his case, we started with an auto
trans bin, and plan on disabling the codes.  I bought TunerCat's tuner
software for it, but I haven't had a chance to try it out yet.  I talked
with Speartech early on in this project, and they told me it would be no
problem to remove trans control from the software for use with the
TH400.  Their quote was reasonable, at $100-$200 as I recall.  They
required a program to start from, and as I recall (This was a year ago)
they wanted the automatic version.
	As for what is causing the problem, I'm just speculating since
I've never tried to look the code.  However, given other software I have
some experience from, I'd wonder about whether the speed sensor is
hooked up or the emissions.  If the speed sensor is not connected, then
the ECM may not allow it to develop full power.  I hope it is not
emissions, since I don't want to install cats on the '84.
	Another possibility is whether the fuel pump is up to spec.
I've read a lot about troubleshooting these engines, and they need 60
psi at the unit or it just won't work.  I've done another conversion
with a '97 engine into a '95 truck, and we had trouble at first with the
fuel pressure.  The fuel pump relay was bad, so it would only run while
the motor was cranking (oil pressure switch).  Anyway, while we were
cranking we would get absolutely nothing until the guage hit 56 psi.
Even when it was at 50 psi, the engine would not fire.  As soon as it
hit ~56 psi, it would fire right up and run like a dream.  If your pump
couldn't provide the pressure at higher RPM's, then it would likely run
poorly then.  If you have a fuel pressure gauge that goes up to 60 psi,
check out the fuel pressure and rule that out.

Jake

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of Ne14RoxCJ
Sent: Tuesday, September 13, 2005 6:31 PM
To: gmecm at diy-efi.org
Subject: RE: [Gmecm] Vortec swap info needed

I'm sure you're right. The data should tell a lot. What would the
difference be if I got the ECM re-flashed to a manual? I know the ECM
doesn't support the TH400, but what support does the TH400 need? Would
the engine run fine just not having a trans hooked to it, or does it
expect to see some input from the trans? If so, what does it need? Would
changing the program to a manual cal change the spark tables and other
parameters? It's not really a manual and (from what I've seen in the
older stuff) the spark and fuel tables are different for a manual. But,
if we're getting it re-flashed anyway, I'll see about getting that trans
control removed. The install of the ECM and wiring is embarrassing to
look at. The guy spent well over $30k in the last year building this
buggy and it looks like he is really skimping in this area. I just want
to make it run like a chevy truck should. If we can do it inexpensively,
that would be great. The engine uses a MAF and no, the engine light is
not on. There isn't one installed. Its going to be a bit of a project to
make this thing right. Thanks for the replies.

Beau

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of terry
Sent: Tuesday, September 13, 2005 7:07 PM
To: gmecm at diy-efi.org
Subject: Re: [Gmecm] Vortec swap info needed

the pcm will have to be flashed to manual trans if it
has not already been done, the vortec pcm doesn't
support the 400 trans.are you running a maf or is it 
speed density, is the engine light on, i believe data 
will tell the story
terry

--- Ne14RoxCJ <ne14roxcj at comcast.net> wrote:

> A friend of mine is having problems with his rock
> crawler. He built the
> buggy and put a Vortec 5.7l in it without any smog
> equipment, no AC, and a
> TH400 trans. Whoever he bought the engine and wiring
> from just hacked off
> the wires that weren't needed. I tried to hook up
> the Snap-on scanner only
> to find out that the data wires were also cut out of
> the DLC connector. The
> problems he is having is a lack of power. It idles
> great and in low range it
> crawl's fine (a geo engine would crawl great with
> the 4:1 t-case and 5.13
> gears). But when it gets revved a little, it starts
> cutting out. I know that
> we need to properly cap these un-used wires and I
> expect we will need to
> have the ECM flashed to get rid of the smog stuff
> and whatever else is not
> used. I haven't dealt with these later model systems
> yet, so can anyone tell
> me what else I'll need to do to make this a V-8
> again instead of the 4-cyl
> that it's acting like. I know that getting the DLC
> put back together and
> looking at the data is the first thing, but what
> else needs done if
> anything?
> 
>  
> 
> Thanks a lot in advance,
> 
> Beau
> 
> > _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org http://lists.diy-efi.org/mailman/listinfo/gmecm
> 

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