ping

[Knowlden and or Eller]

David, I wouldn't rule out an injector causing the ping. I believe you have
only one O2 sensor on the drivers side exhaust so the computer only "sees"
the mixture for those four cylinders. If have a lean problem on the
passenger side the symptoms would be excessive knock retard and finally
audible ping.

Bob


-----Original Message-----
From: owner-gmecm at esl.eng.ohio-state.edu
[mailto:owner-gmecm at esl.eng.ohio-state.edu]On Behalf Of David Mulvey
Sent: Monday, August 23, 1999 2:24 AM
To: gmecm at efi332.eng.ohio-state.edu
Subject: Re: ping




> At 06:58 PM 8/22/99 -0800, you wrote:
> >I have an 87 IROC-Z 5 Liter, I think I have the 12277165 but I am not
> >sure.


> WOT is Wide Open Throttle...
>  From the sound of it and the multiple weirdnesses you are seeing, I'd
> suspect a ground gone bad for the computer or sensors...

I did check the signal wire from the MAF to the computer.  Also the signal
wires to and from the MAF relays.  However, a thorough
check of the ground wires I did not do. I did add two ground wires from
block to the body on both sides of the engine.  But still a
frayed ground wire to the computer or dirty contact might cause some
trouble.

I suppose another "weird" cause could be noise from the ignition system.
The MAF signal wire goes right by the distributor and coil.
Maybe a choke filter could be used on the MAF signal wire (if it's noisy) to
allow only DC voltages to go down the wire.  I'll check
it out this week sometime.  School starts this week, 2nd semester of
calculus and homework will disable my free time as I know it.

I don't get any lean/rich errors.

The ping only happens after the car has warmed up for 7 minutes and WOT and
semi-WOT. From talking to folks here on the list that
means that maybe what circuit is giving bad readings is not being used,
and/or when cold the car will get a richer mixture keeping the
ping away and maybe also the timing is kept to a set algorithm rather than
relying on sensor data for timing.

The more I keep typing, the more I know I need a laptop/Diacom.  I have
their brochure here.  Any used Diacoms out there that need a
new home?



end
----
David Mulvey KD6BZN
Lancaster, CA
(661) 723-0352