A few newbie questions...

[Rex Weatherford]

I'm back..  (we'll I've just been lurking since I've been moving)

I have downloaded and printed "Tuning Tips", "Tuning 101", and "what do I
need to get started".  I will be reading these over and over till I
understand them, or have more questions, whichever comes first. ;^)

Here's my car 92 Chevy Beretta GTZ 2.3L Quad4.  I can't remember the ECM #
and BCC right now, but I don't think that matters yet for my questions...
(it will later I know)  I did some work on this car to help with the
breathing aspects (exh manifold, pipes, converter, muffler) and borrowed a
diacom to check everything out several months ago.  At that time I detected
knock at high RPM's near my TQ peak.  I pulled the plugs and yes I did seem
to have some little black specs on the plugs, so I expected that I was low
on fuel.  They also looked lean, but I just randomly checked them, not after
a WOT run (which I just read about).  I'm going to change my fuel filter and
try some plug reading and see if it is still looks lean on a WOT run.

One of my questions is this..

When using the diacom I recorded knock and had large amounts of knock
retard.  None of it is audible, but the car is rather loud.  The O2 levels
looked OK (.876-.920) but that is with a Bosch sensor from Pep Boys..  The
disturbing part was the amount of KR being dialed in! It goes from 3-20
degrees.  It varies from 17-20 degrees at 5000-6900 RPM.  When this happens
my total advance drops to 12-16 degrees.  I can view the TQ decreases on the
dyno when this happens.  My calculated duty cycle at these RPMs is 70-90%.
So is the Bosch sensor incorrect, or does it not really matter what it says?
I would think that .876-.920 would be a decent reading (I understand these
are not linear, so I don't expect real accuracy, but thought that it would
be ballpark)

I also tried using ~50% mix of  BP 93 octane mixed with VP 103 (or 100)
octane racing fuel and I still got the same KR.  I tried changing the knock
sensor and that didn't help either.  Perhaps this is some mechanical noise?
Does viewing a dyno run help anyone with this?

So can I change the fuel table (where ever that is) and up my injector PW
more or is the factory program already using about all that they can give?
I would assume that 90% is about max before you upgrade? (as someone else
here said earlier today)  I would also like to change cams and things later,
but want to get things running correctly first, and fix my current problems
while learning.  I'd like to tackle WOT issues first, since that is where I
do most of my racing..

I DO know that my head has been changed due to repair and the exhaust ports
are smaller.  I do not know if the chamber size is different.  Could exhaust
port size cause this too?  Should I tear down the motor just to change heads
to try to alleviate this problem?  I hate too, because the head gasket is
holding good and the other head is prone to cracking.

If anyone out there is currently tuning Quad4's and has any idea on this
please let me know.  ( I know that Will is out there somewhere)

I am now located in Central MO so if there is anyone out here, please give
me a shout!  I'll need help later as I accumulate the hardware and software
necessary to communicate with my car.

Thanks and sorry for this repeat question, some have helped with it before,
but I had a few updates to add.

Rex

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