Stumped by TPI

[Ludis Langens]

Jim Santoro <sebring at vnet.net> wrote:
>I have a '88 5.7 Chevy with TPI running in my Sebring MX. The wiring harness
>is an old Street and Perf. speed density job using a '7170 ECM.(V6-Fiero).

What does your harness do with pin J1-D3 on the ECM?  The ECM hardware
defaults to a six cylinder port injected setup.  Grounding J1-D3 switches it
to work with eight cylinders.  (There is no way for the CalPak and MemPak to
do this switch for you.)  What this changes is the number of distributor
reference pulses needed per injector pulse.  (There is also an ECM input
that makes the ECM hardware go to a four cylinder setup.)

>Thanks Steve,I have a scantool and the coolant sensor seems ok. Here are
>the readings.
>Temp sensor 200

Is that 200 degrees F, or just "200"?  "200" means 110 C or 230 F.  (I assume
this is the CTS - this ECM also uses a MAT sensor.  A MAT of "200" is 20 C.)

>TPS voltage .58

256 * (.58 / 5) => 30  Looks OK.

>MAP 1.2v

256 * (1.2 / 5) => 61 => 33 KPa absolute pressure.  Looks OK.

>about 80 O2 crosscounts in 5min running
>inj pulse width 100ms (this can't be right, may be a bug in scantool)

Does it say "100mS" or just "100"?  It could mean 100/65517.1875 or 1.5 mS.

>idle speed 950

This ECM is hard coded to compute the RPM for a V6.  So your real V8 RPM is
950 * 6/8, or 712 RPM.  Do you have a tach that can confirm this?

>and for some reason the scantool does not report the BLM or Itegrator.

What sort of scan tool do you have?  Is there a way to get a raw dump of the
ALDL data - I could tell you what all of it means.  It would be _real_ useful
to know the BLM and Int.

>Have tried 3 different proms, S+P, Hypertech etc.

What sort of PROMs are these?  Are they meant for this setup, or are they
Fiero PROMs?  As I mentioned, this ECM is hard coded for a six.  This cannot
be changed via the PROM.  It ought to be possible to have a calibration for
an eight, but all the RPM related items will have to be specified in
different units.

Did this setup ever run fine?  If not (and you have a stock V6 PROM), the
volumetric efficiency of your V8 might be different enough from the Fiero V6
that the ECM can never get the fueling correct

                   unsigned long BinToBCD(unsigned long i) {unsigned long t;
Ludis Langens         return i ? (t = BinToBCD(i >> 1), (t << 1) + (i & 1) + 
ludis at netcom.com                 (t + 858993459 >> 2 & 572662306) * 3) : 0;}