Knocking Problem in 1990 Corvette L-98

[David A. Cooley]

Sounds like the "part throttle mods" may have been to eliminate EGR...
Have you put the stock chip back in to see if the knock goes away?  If so,
it's not the intake mods.
Let us know what happens,
Dave



At 08:45 PM 10/19/98 -0400, you wrote:
>I have a 90 Vette with a ported plenum and Performance Resources chip with a
>few other minor modifications.  I am having a problem with pinging and have
>been monitoring the engine with an Auto X-Ray system.  The porting of the
>plenum involved removing the walls behind the throttle plates but in front
>of the EGR passages.  I think they may have been there to establish a low
>pressure area for introduction of EGR.  With them removed, I may have upset
>the pressure balance of the original design.  I have found my pinging
>problem to occur in two block cells, number 10 and 14.  Does anyone know
>what these cells are defined as?  Block 14 occurred
>tonight at fairly low speed (28 mph) and 28% throttle angle.  I don't have
>the data on block 10 but it occurred at around 55 mph with slight throttle.
>My block learn numbers are also kind of low for these two cells.  The rest
>of the cells that I have observed so far range from 120 to 132 so on average
>I am in the vicinity of the magic 128 value.  Does anyone know if these
>cells are controlled by programming in the chip.  I am suspicious that the
>new Performance Resources chip I installed is the cause of this problem as
>they advertise "modified partial throttle" enhancements.  Also, I do not get
>any retard at WOT until about 4000 RPM after which the amount of retard
>grows to about 5 degrees at 5000 RPM.  Is this normal or is this another
>chip problem?
>
>Bob T
> 
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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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