[Fwd: New member needs help]

[J Norris]

The distributor has a new cap, rotor, pickup coil, ignition coil, module,
capacitor and new wire leads on both ends.  The entire unit is brand new.  With
EST disconnected it runs like crap.  I will check the procedure you outlined
though.

Thanks

Jason Norris



Walter Sherwin wrote:

> Jason...........You might want to examine your distributor very closely.
> The early 90's distributors of that style were prone to a number of maladies
> which tended to create the exact symptoms you have described, since their
> "Reference Signal" is the heartbeat of the entire fuel injection system.
>
> In this order..............1) run the car with the EST timing connector
> disconnected and note whether or not an improvement exists.    2)  examine
> the timing mark, with a timing light,  both with and without EST connected.
> Is the timing stable?   3)  with the EST disconnected, and while watching
> the timing mark with a timing light, look for an ever so slight timing
> advance with increasing RPM.  Then look for a gross timing shift of +6
> degrees at 2000 RPM or less.  If the timing initially retards,  or
> experiences the gross shift at more than 2000 RPM, then your distributor is
> bad.   4)  if all of these checks are okay, then your distributor is okay,
> and your problem is elsewhere.
>
> Stay in touch..............
>
> -----Original Message-----
> From: David A. Cooley <n5xmt at bellsouth.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Wednesday, November 18, 1998 3:12 PM
> Subject: Re: [Fwd: New member needs help]
>
> >Jason,
> >The popping was definitely from an extremely lean condition.  The High TPS
> >could have been a problem, but without having a GM cal for that vehicle in
> >front of my, this is only an educated guess based on what I have seen in
> >other cals... The TPS has a high and low limit.  Exceed either limit and it
> >goes back to closed loop because it thinks the TPS may have a problem.  I'm
> >surprised the ECM didn't set a TPS voltage too high code.
> >
> >What did diacom say the TPS voltage was when it started popping?
> >
> >Also, a fuel pressure guage OUTSIDE THE CAR you can see while driving would
> >help... Could have a bad conn. to the FP making it cut out and go lean as
> >FP drops.  Also, some smart a$$ may have dumped a raw egg into your gas
> >tank... when you accelerate hard, it slides around until it covers the FP
> >pickup and cuts off fuel.
> >Later,
> >Dave
> >
> >
> >
> >At 02:22 PM 11/18/98 -0500, you wrote:
> >
> >>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
> >
> >===========================================================
> >           David Cooley N5XMT           Internet: N5XMT at bellsouth.net
> >     Packet: N5XMT at KQ4LO.#INT.NC.USA.NA   T.A.P.R. Member #7068
> >       I am Pentium of Borg...division is futile...you will be
> approximated.
> >===========================================================