Oxygen sensor and high speed stumble

[mrvette]

I would put the stock chip back in  and reduce the fuel pressure to ~38-40 psi
at just pump running, not engine....and see what happens...
asupposedly you are running 89+ octane fuel...GENE

The Thibodeaus wrote:
> 
> I have an 90 Vette with a L-98 which above 4000 RPM loses performance and
> it has been suggested it is starving for fuel.  The fuel filter has 500
> miles on it.  I pumped some fuel out of the tank tonight after shaking the
> car to check for any sediment and the fuel looks fine.  I am running an
> adjustable fuel pressure regulator set at 48 psi.  I pulled the oxygen
> sensor tonight and it had some black soot on it indicating a rich
> condition.  Here is my question, by upping the fuel rail pressure to 48 psi
> am I starving the engine at high RPM because the pump can't flow enough
> fuel at that pressure?  Does this seem logical?  I increased the pressure
> compensate for a ported plenum and also to overcome a pinging problem
> (several prior posts made to this board and Vettenet on this nightmare) but
> it hasn't worked.  I am working with the chip programmer to resolve some of
> the pinging problems because I have found that they completely shut of the
> EGR function.  So, should I lower my pressure?  Any suggested value?
> Thanks for any suggestions.
> 
> Bob T

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