Stumped by TPI

[Shannen Durphey]

Jim Santoro wrote:

> Hi All,
>
> 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).
> The Problem:
> The car runs extremely rich all the time but mostly under 2500rpm.
> Motor is bone stock. No codes set. Plenty of O2 crosscounts.No vacuum
> leaks.
> Map voltage is 1.2 at an idle. Is this normal?
> Have tried 3 different proms, S+P, Hypertech etc.
> Is anyone else running this setup? (fat chance)
> Should I just bite the bullet and update to a newer harness/ECM.
> Suggestions, comments flames are welcome.
> Regards,
> Jim Santoro   sebring at vnet.net

  Hi Jim.

I'm guessing that you know it runs rich by the smell at the tail pipe?
If the O2 sensor is reading that, you should see rather high voltages on
the scantool.  In the case of an oxygen leak into exhaust, you should see
low voltages on the scanner.  Does the scanner have a rich/lean
indicator? Where does it stay?  I don't always trust crosscounts as an
indicator because aftermarket sensors/cats can send funny readings.

Your car probably doesn't have a cold start injector, I think that ended
in '87.  But if it does, make sure it isn't staying on.  And make sure
your fuel pressure is OK.  If you disconnect the O2 and force it into
open loop does it run better?  That would indicate problems in the
feedback circuit.

What are you using for a scantool?  It would be really nice to know what
block learn and integrator are doing.

Oh yeah.  I am assuming this car ran correctly at one time.  True?  If
it's always run rich there might be some kind of configuration, plumbing,
wiring, etc problem.

Hope this helps.

Shannen