A few newbie questions...

[Bruce Plecan]

> 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.

You'll only hear it when you exceed the amount of retard the chip allows, if
you hear it pining, get out of it!.

>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!

The O2 dialed in KR?.

>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.

Just like it should.

 >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?

In general ignore it..

> 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?

Always that chance.

> Does viewing a dyno run help anyone with this?

Maybe for finding an exhuast rattle.

> 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?

Depends on what's in the chip.

> 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'd lighten up on the racing till you find out where and what to change, and
rather risk blowing it up learning start with the low chance of china
syndroming the engine areas.
Bruce


> 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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