Using TBI on moded 5.7

[Mike Vannorsdel]

Cheating?  Sorry but I assembled the engine and had it running in 5 hours(day after
the first post).  I have tons of engine building experience, mostly carbed, anywhere
from 200-1000hp.  The TBIs I have used were Holley and were fully adjustable.  I'm
not too familiar with the Rodchester.  My soul problem lies in just a rich idle
circuit and too much accelerator charge(causing poor response).  I have removed the
PCV and plugged the port because I was tired of the oil coated intake runners.  The
injectors give a nice cone spray and seem to be great.  All I could figure that was
responsible for the rich idle and heavy accelerator shot is the TPS.  So naturally I
replaced it.  Same thing.   I'm trying to understand why the ecm is wanting to give
so much fuel at idle and throttle opening.  All of the engine sensors have been
replaced and give good readings except for the TPS which I was told specs for it
were 0.5v idle and 4.5-5v WOT.  The problems occur in closed and open loop.  I know
the problem but don't know how to correct it on the TBI.  That's what I'm looking
for:  how do I lean the idle and lean the accelerator shot?

Shannen Durphey wrote:

> gmecm at efi332.eng.ohio-state.edu wrote:
> >
> > I'll keep messing with it hope to find something.  The part that really bugs me
> > is no TPS adjustment.  It's possible I'm looking in the wrong spot.
> >
> Ok, I've reached my limit.  If you suspect the TPS is causing a
> problem at idle because of the voltage, use your spare TPS and set it
> at the voltage you want.  In my experience, .78v is not a problem.  My
> 747/crossfire equipped pickup is set to .75v.  The specs I posted are
> the specs I use in the dealership.  Take that however you'd like.
> Next...
>
> You're smarter than the ECM.  Do you suspect the engine's running
> rich?  Lean it out.  Do you suspect lean?  Richen it up.  Eliminate as
> many sensors as possible, force the ECM to do what you want.  Have you
> diagnosed problems with a carburetor? If you've been succesful before,
> you can do it here.
>
> Is the ECM in closed loop when it hesitates?  Open?  What are the O2
> voltages?  Fuel pressure?  Block learn and integrator numbers?  Does
> the engine smooth out if you bring up the rpm?  What tools are you
> using to diagnose this?  Do you have a scan tool?  Factory manual?
>
> The engine in my pickup is a Chev 302, crossfire injection, 7747 ECM,
> 9.5:1, with 214/224 dur @.050, 140 deg LSA,.443 gross lift cam.  It
> idles well, little sign of lumpedy-ness (far cry from the old
> crossfire ecm ; > ).  Your combination should also work well.  The cam
> is smaller and the displacement is larger.
>
> Lotsa sharp folks on this list.  Ask for what you want, give us a good
> starting point, and you'll get some useful answers.  You snuck in with
> a request for opinions on possible modifications, and ended up talking
> about a driveability problem.  That's cheating ; ) and it doesn't
> really paint a clear picture of what's going on.
> Shannen