Oxygen sensor and high speed stumble UPDATE

[David A. Cooley]

>when tuning.  Does the pinging problem originating from a particular 
>cylinder(s), or are they all pinging?  Just curious whether one 
>cylinder might be getting inadequate fuel delivery for some 
>reason, which you're not seeing on the sensor because of the overall 
>rich condition.  	

One thing to keep in mind here, is that knock picked up by the knock sensor
doesn't mean something is wrong.
I have spoken with a guy that works for Delco that does some of the Timing
calibrations.  He has said that they make the timing tables "tickle" the
knock sensor on the best fuel they design the engine/cal for to ensure that
the timing is kept at the max allowed for the conditions at hand.  If they
wrote the cal so it never knocked, then timing wouldn't be as advanced as
possible for that combo.
You stated it was running 29 degrees advance at WOT.  this was with 4
degrees retard.  That means the cal table is requesting 33 degrees at WOT.
If you get your hands on some 100 octane unleaded and try it, you'll
probably see the timing go all the way to 33 degrees at WOT with 0 retard.
The tables were set for 93 octane on the vette and any other performance
vehicle that is recomended to run Premium in.
With O2 sensor voltages in the 900mv Range at WOT, I'd leave fuel and
timing alone.
The knock you are detecting at part throttle with the aftermarket chip is
from lack of EGR... Guaranteed that the chip people only removed the EGR
and didn't fix the EGR timing and fuel tables to make it run right without
the EGR... GM adds timing and leans the fuel during EGR so there is no loss
of power from the EGR.  Take away the EGR, and now the timing is way too
high, and the fuel is too lean because the part of the combustion air that
was recirculated exhaust is now air and it needs fuel.
This is why a lot of chip makers charge a fortune hoping no one knows what
the tables contain... it shows they have no clue as to what they are doing.
If you want a chip that will make the car run better, try a reputable name
like Z Industries... Ron Zimmer has friends in the automotive manufacturer
industry that supply info and his chips are actual dyno tested units... not
a bit changed here and there to make it look like they did something.
Later,
Dave

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           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.
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