[Fwd: New member needs help]

[J Norris]

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Date: Wed, 18 Nov 1998 08:27:01 -0500
From: J Norris <jwn at sgi.net>
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To: "diy_efi at efi332.eng.ohio-state.edu" <diy_efi at efi332.eng.ohio-state.edu>
Subject: New member needs help
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Reply-To: diy_efi at efi332.eng.ohio-state.edu

Hello everyone:

    I am new to this list and I am looking for some help.  I have been
having a problem with my 89 Corvette L-98 6 speed.  For months now I
have been battling a problem that has been really frustrating.
Sometimes, when accelerating the car has no power at WOT and I have a
rapid popping/backfiring/missing thing going on.  I finally broke down
and got a Diacom and recorded the event.  When it happened at WOT, my O2
reading dropped to 0 and my integrator climbed to 180 while my inj.
pulse width was 9.5ms or so.  Now there was two thing I immediately
noticed.  One why the extremely lean condition and two, how come my Int.
and BLM were not 128?  I found the answer to number 2 last night.

    My TPS voltage was .55 at idle and 4.98 at WOT.  The ECM will not go
into open loop PE mode at this high of a voltage.  At this high setting,
the ECM was trying to maintain a 14.7:1 air fuel ratio.  I readjusted
the TPS to 4.63 volts max and BINGO!  The ECM goes into open loop rich
condition.

    Now, the million dollar question is could the high TPS voltage at
WOT cause the lean condition I am experiencing?  The fuel pressure is
fine (37 psi at idle 45 psi at WOT) but I never had an opportunity to
check it while the seemingly lean condition was occurring.  The fuel
filter is new, the injectors were leak tested and balance tested and the
O2 sensor is new.

    I have Excel sheets I send if anyone would be nice enough to view my
data and try to help me.

Thanks again,

Jason Norris


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