New member needs help

[Mark Romans]

Sounds like a restricted fuel filter or bad pump.  You need to check the
fuel pressure when it is acting up.  14.7 at wot won't cause much of a loss
of power.
Mark
-----Original Message-----
From: J Norris <jwn at sgi.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, November 18, 1998 5:44 AM
Subject: New member needs help


>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
>