Re: EPROM Programming

[Shannen Durphey <shannen@grolen.com>]

WEG1192@aol.com wrote:
> 
> Mark and all,
> 
> I had searched the archive for VSS and apparently Greg Parmer came to the
> same conclusion I did that the VSS is needed although the "experts" say I
> don't need one. What I am trying to determine is if the "experts" at TPIS,
> Turbocity, and Howell are all wrong.

I have an efi converted pickup.  It has a manual transmission. I have
not yet installed the VSS.  I have had to play with spark and fuel and
increase idle speed slightly so it won't stall on deceleration. 
Mileage is down from 18 mpg with previous ecm (with VSS installed) to
about 10.  The ecm will not enter highway spark mode (which is used to
improve mileage on road trips) without VSS input.  I am also a
professional mechanic.  I have worked on many GM cars.  I have seen
problems similar to the ones described above, caused by a faulty VSS. 
Do you _need_ one?  No.  Then again, did you _need_ to swap to efi? 
You've gone through the work to realize the benefits, why not continue
the effort and get the most you can?

Oh, yeah.  TC story.  Converted the pickup to crossfire, used ecm that
came with the crossfire.  TC made a chip, cost like $117, said would
work fine.  Truck stalled when engine partly warmed up and coming up
to stop sign.  Also ran too rich until in closed loop.  Called TC,
spoke on phone for a while, was told to record all the data I could
with the scantool, send the chip back, and would get reburn for $50. 
Spoke more, I said that first burn was supposed to be right, shouldn't
have to pay for #2.  Was told to turn up the throttle opening if I
felt that strongly.  TC had bad answers, and (to be fair) chip maker
had no way to get the chip right the first time.  Never sent the chip
back for retune, started down the road to DIY.
BTW, has anyone gotten past the secretary at Howell?

> They all say a VSS is not needed except
> for autos. 
"They"?  "They"?? "They" also said flight was impossible at one time.
: )  Your dilemma is a definite result of "asking someone who's been
there".  I have also been there, I have a different opinion.

Also, TPIS charges $475 for their level 5 EPROM chip. Are you
> saying that even at that price they are not that good? 
Lessee....  $475 gets you a burner, eraser, 50 blank eproms, and ~
$250 worth of time to burn your own.  Do you want to know your
calibration like a cowboy knows his horse?


> I began to question things when I was told by TPIS how to set my fuel
> pressure on my TPI. They said to run at WOT and measure the voltage on my O2
> sensor. It should be 0.85 volts according to them. Well, I can't get there.
> It pegs at 0.72 volts. But according to Thrasher-EP's site, since the BLM
> cell 15 is used in WOT calculations for fuel, the ECM is compensating for the
> increased fuel pressure and I will never get there. Their chip supposedly
> fixes this problem by resetting cell 15 to 128. So are they correct or are
> they not? TPIS says no. It's frustrating when the truth depends on who you
> ask. Does anyone here agree with Thrasher?

Engine tuning by committee.  I like it.  First question:  Have you
caught on to the fact that the O2 sensor reading is not a reliable
tuning aid?  Next question:  Did you determine that the stock pressure
and regulator was not sufficient?
Sorry for the beating, just seems like you're main concern is finding
flaws with the commercial sites' info, not tuning your vehicle.
Shannen
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